UDP - User Datagram Protocol
What is UDP?
UDP stands for User Datagram Protocol. It’s a communication protocol used for fast, connectionless data transmission between devices on a network. Unlike TCP, UDP does not guarantee delivery, order, or error checking — it simply sends packets and doesn’t wait for acknowledgments.
Why is UDP useful?
UDP is useful when speed is more important than reliability. It’s ideal for applications where: * Occasional data loss is acceptable. * Real-time performance is critical. * Overhead from connection setup and error correction is undesirable.
How it works?
No connection setup – The sender just starts sending packets to the receiver.
Packets are sent – Each packet (called a datagram) is sent independently.
No acknowledgments – The sender doesn’t wait to see if the packet was received.
Receiver processes data – The receiver handles whatever packets it gets, in whatever order they arrive.
Where is UDP used?
Video streaming – Like live broadcasts where speed matters more than perfect quality.
Online gaming – Fast-paced games use UDP to reduce lag.
Voice over IP (VoIP) – Real-time voice communication prefers speed over reliability.
DNS lookups – DNS queries are small and fast, making UDP ideal.
Why OSI Layer: Transport Layer (Layer 4)?
It handles end-to-end communication between devices.
It provides port numbers to distinguish different services on the same device.
It enables multiplexing of data streams, even though it doesn’t manage reliability or ordering like TCP.
What are the key features?
Connectionless Protocol.
Unreliable Delivery.
No Ordering.
How does a server know where to reply in UDP?
Each incoming UDP datagram includes: * Source IP address. * Source port number. The server uses these to send a reply.
What is a datagram?
A datagram is a self-contained packet sent via UDP that includes both header and data. Each datagram is independent.
Why is UDP used if it’s unreliable?
Because it’s: * Fast and low-latency. * Requires less overhead. * Suitable for real-time or loss-tolerant applications.
What are some applications that use UDP?
DNS (Domain Name System).
VoIP (Voice over IP).
Video Streaming.
Online Gaming.
TFTP (Trivial File Transfer Protocol).
DHCP (Dynamic Host Configuration Protocol).
SNMP (Simple Network Management Protocol).
NTP (Network Time Protocol).
What is the working flow of UDP?
No Connection Needed: * UDP is connectionless — no handshake before sending data. * Sender just sends data directly. Data is Packed into Datagrams: * Each piece of data is packed into a UDP datagram. * Datagrams are independent (no sequence tracking). Datagram is Sent to Destination: * The sender sends the datagram to the receiver’s IP and port. * No guarantee of delivery. No Acknowledgment: * Receiver may or may not respond. * UDP does not expect or send ACKs. No Order or Reliability: * Packets may arrive out of order, or not at all. * It’s up to the application to handle errors, duplicates, or missing data. Receiver Gets Datagram: * If the datagram arrives, the receiver processes it immediately. * If it’s lost, UDP does nothing.
Is UDP suitable for real-time applications?
Yes — UDP is ideal where speed matters more than reliability, like: * Online gaming. * Video conferencing. * Voice calls.
Topics in this section,
In this section, you are going to learn
Terminology
Version Info
S.No |
UDP Version |
RFC |
Year |
Core Ideas/Contribution |
|---|---|---|---|---|
1 |
UDP (Original) |
RFC 768 |
1980 |
Introduced UDP as a simple, |
connectionless transport layer protocol; provides minimal services like checksums and port numbers. |
||||
2 |
UDP-Lite |
RFC 3828 |
2004 |
A variant of UDP that allows partial checksum |
coverage, useful for multimedia applications |
||||
where some data loss is tolerable. |
||||
3 |
UDP with ECN |
RFC 6040 |
2010 |
Describes how to use Explicit Congestion |
Notification (ECN) with UDP to improve |
||||
congestion control. |
||||
4 |
UDP Guidelines |
RFC 8085 |
2017 |
Provides guidelines for applications using UDP, |
|
||||
5 |
UDP Options |
RFC 7510 |
2015 |
Defines UDP encapsulation for IPsec VPNs, |
allowing NAT traversal. |
||||
6 |
UDP Options Framework |
RFC 9298 |
2022 |
Introduces a framework for extending UDP with |
options, enabling new features while maintaining backward compatibility. |
setup
setup
UDP UDP Packet
S.No |
Protocol Packets |
Description |
Size(bytes) |
|---|---|---|---|
1 |
UDP |
65535 |
|
UDP Header |
8 Bytes total |
8 |
|
Source Port |
Identifies the port number of the sender. |
2 |
|
Destination Port |
Identifies the port number of the receiver. |
2 |
|
Length |
Specifies the total length of the UDP packet,including the header and data. |
2 |
|
Checksum |
error-checking the header and data. |
2 |
|
Data(UDP Payload) |
Contains the actual payload being transmitted. |
variable(65507) |
S.No |
Use Case |
Descrption |
|---|---|---|
1 |
DNS (Domain Name System) |
UDP is used for fast, lightweight queries and responses between clients and DNS servers. |
2 |
VoIP (Voice over IP) |
UDP supports real-time voice communication with low latency, tolerating some packet loss. |
3 |
Video Streaming |
Used in live streaming where speed is prioritized over reliability (e.g., RTP over UDP). |
4 |
Online Gaming |
Enables fast transmission of game state updates with minimal delay. |
5 |
DHCP (Dynamic Host Configuration Protocol) |
Uses UDP to assign IP addresses quickly and efficiently. |
6 |
TFTP (Trivial File Transfer Protocol) |
A simple file transfer protocol using UDP for minimal overhead. |
7 |
SNMP (Simple Network Management Protocol) |
Uses UDP for lightweight network device monitoring and management. |
8 |
NTP (Network Time Protocol) |
Synchronizes clocks over a network using UDP for quick time updates. |
9 |
IPTV |
Delivers television content over IP networks using UDP multicast. |
10 |
Sensor Networks / IoT |
UDP is used in constrained environments for fast, low-power communication. |
S.No |
Feature |
Descrption |
|---|---|---|
1 |
Connectionless Protocol |
UDP does not establish a connection before sending data, reducing overhead. |
2 |
Low Latency |
Ideal for real-time applications due to minimal delay in data transmission. |
3 |
No Acknowledgment |
UDP does not confirm receipt of packets, making it faster but less reliable. |
4 |
No Flow Control |
It does not manage data rate between sender and receiver. |
5 |
No Congestion Control |
UDP does not reduce transmission rate in response to network congestion. |
6 |
Checksum for Error Detection |
Provides basic error checking using a checksum field in the header. |
7 |
Supports Multicast and Broadcast |
Efficiently sends data to multiple recipients. |
8 |
Lightweight Header |
The UDP header is only 8 bytes, making it efficient for small data packets. |
9 |
Port Numbers |
Uses source and destination port numbers to direct data to the correct application. |
10 |
Stateless Communication |
Each packet is treated independently, with no memory of previous packets. |
Connectionless Protocol - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Send Datagram |
Send a single UDP packet |
Packet sent successfully |
2 |
Receive Datagram |
Receive a UDP packet |
Packet received successfully |
3 |
No Handshake |
Start communication |
No connection setup required |
4 |
No Acknowledgment |
Send packet |
No ACK expected |
5 |
Packet Loss |
Drop packet in transit |
No retransmission |
6 |
Packet Duplication |
Duplicate packet |
Receiver may get multiple copies |
7 |
Packet Reordering |
Reorder packets |
Receiver gets out-of-order data |
8 |
No Flow Control |
Send burst of packets |
Receiver may drop excess packets |
9 |
No Congestion Control |
Send during congestion |
Packets may be lost |
10 |
Stateless Communication |
Send without session |
Server handles each packet independently |
11 |
Broadcast Packet |
Send to broadcast address |
All nodes receive packet |
12 |
Multicast Packet |
Send to multicast group |
Group members receive packet |
13 |
Unicast Packet |
Send to single host |
Target host receives packet |
14 |
Port Unreachable |
Send to closed port |
ICMP error may be returned |
15 |
No Retransmission |
Drop packet |
No retry attempted |
16 |
High Throughput |
Send many packets quickly |
High-speed transmission |
17 |
Low Latency |
Measure delay |
Minimal transmission delay |
18 |
Packet Size Limit |
Send max-size packet |
Packet accepted ( 65,535 bytes) |
19 |
Oversized Packet |
Exceed size limit |
Packet dropped or fragmented |
20 |
Fragmented Packet |
Send fragmented datagram |
Reassembled at receiver |
21 |
Corrupted Packet |
Simulate bit error |
Packet may be discarded |
22 |
No Ordering Guarantee |
Send multiple packets |
Order not guaranteed |
23 |
Stateless Server |
Server handles each request independently |
No session tracking |
24 |
Stateless Client |
Client sends without session |
No connection state |
25 |
Packet with Delay |
Introduce delay |
Packet still received |
26 |
Packet with Jitter |
Vary delay between packets |
Receiver handles jitter |
27 |
Packet with Loss |
Drop random packets |
No retransmission |
28 |
Packet with Duplication |
Send same packet twice |
Receiver may get duplicates |
29 |
Packet with Reordering |
Change packet order |
Receiver gets unordered data |
30 |
Packet with TTL Expiry |
Set low TTL |
Packet discarded en route |
31 |
Packet with Invalid Checksum |
Corrupt checksum |
Packet dropped |
32 |
Packet with Valid Checksum |
Correct checksum |
Packet accepted |
33 |
Packet to Invalid IP |
Send to wrong address |
Packet lost |
34 |
Packet to Valid IP |
Send to correct address |
Packet received |
35 |
Packet to Closed Port |
Send to unused port |
ICMP error may be returned |
36 |
Packet to Open Port |
Send to listening port |
Packet processed |
37 |
Packet Flooding |
Send rapid packets |
May cause packet loss |
38 |
Packet Logging |
Log incoming packets |
Logs generated |
39 |
Packet Monitoring |
Monitor traffic |
Packets visible in sniffer |
40 |
Packet Filtering |
Apply firewall rules |
Packets blocked or allowed |
41 |
NAT Traversal |
Send through NAT |
Packet reaches destination |
42 |
VPN Routing |
Send over VPN |
Packet tunneled successfully |
43 |
Proxy Routing |
Send via proxy |
Packet forwarded |
44 |
IPv6 Support |
Send over IPv6 |
Packet transmitted |
45 |
IPv4 Support |
Send over IPv4 |
Packet transmitted |
46 |
DNS Query |
Send UDP DNS request |
Response received |
47 |
VoIP Packet |
Send RTP over UDP |
Audio transmitted |
48 |
Video Stream |
Send video over UDP |
Stream received |
49 |
Game Packet |
Send game data |
Real-time update received |
50 |
UDP Hole Punching |
Establish peer-to-peer |
Connection established |
Low Latency - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Send Small Packet |
Transmit minimal data |
Packet sent with minimal delay |
2 |
Receive Small Packet |
Receive minimal data |
Packet received instantly |
3 |
No Handshake Delay |
Start communication |
No connection setup delay |
4 |
No ACK Delay |
No acknowledgment required |
Immediate transmission |
5 |
Real-Time Audio |
Send audio stream |
Audio received with low latency |
6 |
Real-Time Video |
Send video stream |
Video received with low latency |
7 |
Game Data Transmission |
Send game state updates |
Updates received in real-time |
8 |
Sensor Data Stream |
Send IoT sensor data |
Data received with minimal delay |
9 |
DNS Query |
Send DNS request |
Response received quickly |
10 |
VoIP Packet |
Transmit voice packet |
Voice heard with low delay |
11 |
Packet with Jitter |
Simulate jitter |
Latency remains low |
12 |
Packet with Delay |
Introduce artificial delay |
Delay detected and measured |
13 |
Packet with Loss |
Drop packet |
No retransmission, latency unaffected |
14 |
Packet with Reordering |
Reorder packets |
No delay in delivery |
15 |
Packet with Duplication |
Duplicate packet |
No impact on latency |
16 |
High Throughput |
Send many packets quickly |
Low latency maintained |
17 |
Low Bandwidth |
Send over limited bandwidth |
Latency remains acceptable |
18 |
Network Congestion |
Simulate congestion |
Latency increases slightly |
19 |
No Flow Control |
Send burst of packets |
Immediate transmission |
20 |
No Congestion Control |
Send during congestion |
Packets sent without delay |
21 |
NAT Traversal |
Send through NAT |
Low latency maintained |
22 |
VPN Routing |
Send over VPN |
Latency remains low |
23 |
Proxy Routing |
Send via proxy |
Minimal delay added |
24 |
IPv4 Transmission |
Send over IPv4 |
Low latency observed |
25 |
IPv6 Transmission |
Send over IPv6 |
Low latency observed |
26 |
Local Network |
Send within LAN |
Near-zero latency |
27 |
Wide Area Network |
Send over WAN |
Acceptable latency |
28 |
Satellite Network |
Send via satellite |
Higher latency detected |
29 |
Mobile Network |
Send over 4G/5G |
Low latency maintained |
30 |
Wi-Fi Network |
Send over Wi-Fi |
Low latency observed |
31 |
Ethernet Network |
Send over Ethernet |
Very low latency |
32 |
Packet Size Variation |
Vary packet sizes |
Latency remains low |
33 |
Burst Transmission |
Send packets in bursts |
Low latency maintained |
34 |
Continuous Stream |
Send continuous data |
Stream received with low delay |
35 |
Idle Timeout |
Resume after idle |
Latency remains low |
36 |
Firewall Traversal |
Send through firewall |
No delay added |
37 |
IDS Monitoring |
Monitor for latency |
No latency spikes detected |
38 |
Logging Enabled |
Log packet timestamps |
Latency measurable |
39 |
Logging Disabled |
No logging overhead |
Latency unaffected |
40 |
Packet Timestamping |
Add timestamps |
Accurate latency measurement |
41 |
Packet Prioritization |
Prioritize UDP packets |
Low latency maintained |
42 |
QoS Enabled |
Apply QoS rules |
Priority packets delivered faster |
43 |
QoS Disabled |
No prioritization |
Latency may vary |
44 |
UDP Hole Punching |
Establish peer-to-peer |
Connection setup quickly |
45 |
UDP Broadcast |
Send to all nodes |
Broadcast received instantly |
46 |
UDP Multicast |
Send to group |
Multicast received with low delay |
47 |
UDP Unicast |
Send to single host |
Packet received quickly |
48 |
Packet Fragmentation |
Fragment large packet |
Reassembled with minimal delay |
49 |
Packet Reassembly |
Reassemble fragments |
No delay in final delivery |
50 |
Stress Test |
High volume, low latency |
Latency remains within threshold |
No Acknowledgment - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Send Packet |
Transmit UDP packet |
No ACK expected |
2 |
Receive Packet |
Receive UDP packet |
No ACK sent |
3 |
Packet Loss |
Drop packet |
No retransmission or ACK |
4 |
Packet Duplication |
Duplicate packet |
No ACK, both packets received |
5 |
Packet Reordering |
Reorder packets |
No ACK, order not guaranteed |
6 |
No Handshake |
Start communication |
No setup or ACK |
7 |
Stateless Server |
Server receives packet |
No session or ACK |
8 |
Stateless Client |
Client sends packet |
No ACK expected |
9 |
Broadcast Packet |
Send to all nodes |
No ACK from receivers |
10 |
Multicast Packet |
Send to group |
No ACK from group members |
11 |
Unicast Packet |
Send to one host |
No ACK from receiver |
12 |
Port Unreachable |
Send to closed port |
ICMP error may be returned, no ACK |
13 |
Packet with Delay |
Delay packet delivery |
No ACK, delay tolerated |
14 |
Packet with Jitter |
Vary packet timing |
No ACK, jitter handled |
15 |
Packet with Loss |
Drop packet randomly |
No ACK or retry |
16 |
Packet with Duplication |
Send same packet twice |
No ACK, both may be processed |
17 |
Packet with Reordering |
Change packet order |
No ACK, receiver handles |
18 |
Packet with TTL Expiry |
TTL expires mid-route |
No ACK, packet discarded |
19 |
Packet with Invalid Checksum |
Corrupt checksum |
Packet dropped, no ACK |
20 |
Packet with Valid Checksum |
Correct checksum |
Packet accepted, no ACK |
21 |
Packet to Invalid IP |
Send to wrong address |
No ACK, packet lost |
22 |
Packet to Valid IP |
Send to correct address |
Packet received, no ACK |
23 |
Packet to Closed Port |
Send to unused port |
ICMP error possible, no ACK |
24 |
Packet to Open Port |
Send to listening port |
Packet processed, no ACK |
25 |
Packet Flooding |
Send rapid packets |
No ACK, possible loss |
26 |
Packet Logging |
Log incoming packets |
No ACK logged |
27 |
Packet Monitoring |
Monitor traffic |
No ACK observed |
28 |
Packet Filtering |
Apply firewall rules |
No ACK, packet blocked or allowed |
29 |
NAT Traversal |
Send through NAT |
No ACK, packet forwarded |
30 |
VPN Routing |
Send over VPN |
No ACK, packet tunneled |
31 |
Proxy Routing |
Send via proxy |
No ACK, proxy forwards |
32 |
IPv6 Support |
Send over IPv6 |
No ACK, packet transmitted |
33 |
IPv4 Support |
Send over IPv4 |
No ACK, packet transmitted |
34 |
DNS Query |
Send DNS request |
Response received, no ACK |
35 |
VoIP Packet |
Transmit voice packet |
No ACK, real-time delivery |
36 |
Video Stream |
Send video over UDP |
No ACK, stream continues |
37 |
Game Packet |
Send game data |
No ACK, real-time update |
38 |
UDP Hole Punching |
Establish peer-to-peer |
No ACK, connection setup |
39 |
UDP Broadcast |
Send to all devices |
No ACK expected |
40 |
UDP Multicast |
Send to group |
No ACK expected |
41 |
UDP Unicast |
Send to one device |
No ACK expected |
42 |
Packet Fragmentation |
Fragment large packet |
No ACK, reassembly at receiver |
43 |
Packet Reassembly |
Reassemble fragments |
No ACK, data reconstructed |
44 |
Logging Disabled |
No packet logs |
No ACK observed |
45 |
Logging Enabled |
Log packet timestamps |
No ACK logged |
46 |
Packet Timestamping |
Add timestamps |
No ACK, timestamps used for analysis |
47 |
Packet Prioritization |
Prioritize UDP packets |
No ACK, priority respected |
48 |
QoS Enabled |
Apply QoS rules |
No ACK, faster delivery |
49 |
QoS Disabled |
No prioritization |
No ACK, standard delivery |
50 |
Stress Test |
High volume, no ACK |
System handles load without ACKs |
No Flow Control - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Rapid Packet Send |
Send packets rapidly |
Receiver may drop packets |
2 |
Burst Transmission |
Send burst of packets |
No flow control, possible loss |
3 |
Receiver Overload |
Overwhelm receiver buffer |
Packets dropped |
4 |
No Window Management |
No sliding window used |
All packets sent immediately |
5 |
No ACK Feedback |
No acknowledgment from receiver |
Sender continues sending |
6 |
No Rate Adjustment |
Vary network speed |
Sender does not adapt |
7 |
Packet Loss |
Drop packets during overload |
No retransmission |
8 |
Packet Duplication |
Duplicate packets |
Receiver may process both |
9 |
Packet Reordering |
Reorder packets |
No correction mechanism |
10 |
Packet Delay |
Delay packets |
No sender adjustment |
11 |
Packet Jitter |
Vary packet timing |
No smoothing or control |
12 |
Buffer Overflow |
Fill receiver buffer |
Packets lost |
13 |
Buffer Underflow |
Receiver reads too fast |
No impact on sender |
14 |
No Congestion Control |
Simulate congestion |
Sender continues sending |
15 |
No Throttling |
Send at max rate |
Receiver may drop packets |
16 |
No Backpressure |
Receiver cannot signal sender |
Sender unaware of overload |
17 |
No Flow Pause |
Receiver cannot pause flow |
Packets continue arriving |
18 |
No Flow Resume |
No resume signal needed |
Sender keeps sending |
19 |
No Flow Negotiation |
No initial flow setup |
Packets sent immediately |
20 |
No Flow Termination |
No graceful end |
Packets stop abruptly |
21 |
High-Speed Sender |
Send at gigabit speed |
Receiver may drop packets |
22 |
Low-Speed Receiver |
Slow receiver |
Packets dropped due to overflow |
23 |
Mixed Speed Devices |
Sender faster than receiver |
No flow control, data loss possible |
24 |
IoT Device Receiver |
Limited buffer |
Packets dropped |
25 |
Mobile Device Receiver |
Varying network speed |
No sender adjustment |
26 |
Satellite Link |
High latency |
No flow control, possible loss |
27 |
VPN Tunnel |
Send through VPN |
No flow control applied |
28 |
NAT Traversal |
Send through NAT |
No flow control |
29 |
Proxy Routing |
Send via proxy |
Proxy does not control flow |
30 |
Firewall Traversal |
Send through firewall |
No flow control enforcement |
31 |
IPv4 Transmission |
Send over IPv4 |
No flow control |
32 |
IPv6 Transmission |
Send over IPv6 |
No flow control |
33 |
DNS Query |
Send DNS request |
No flow control needed |
34 |
VoIP Stream |
Send voice packets |
Possible jitter or loss |
35 |
Video Stream |
Send video packets |
Possible frame drops |
36 |
Game Data |
Send game updates |
Real-time data may be lost |
37 |
Sensor Data |
Send frequent updates |
Receiver may miss data |
38 |
UDP Broadcast |
Send to all devices |
No flow control |
39 |
UDP Multicast |
Send to group |
No flow control |
40 |
UDP Unicast |
Send to one device |
No flow control |
41 |
Packet Logging |
Log sent packets |
No feedback from receiver |
42 |
Packet Monitoring |
Monitor traffic |
No flow control observed |
43 |
Packet Filtering |
Apply firewall rules |
No flow control |
44 |
Packet Prioritization |
Prioritize packets |
No flow control |
45 |
QoS Enabled |
Apply QoS rules |
No sender-side control |
46 |
QoS Disabled |
No prioritization |
No flow control |
47 |
Stress Test |
High volume test |
Receiver drops excess packets |
48 |
Packet Timestamping |
Add timestamps |
No impact on flow |
49 |
Logging Disabled |
No logs |
No flow control observed |
50 |
IDS Monitoring |
Monitor for overload |
Alerts triggered due to lack of control |
No Congestion Control - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
High Bandwidth Usage |
Send large data continuously |
No throttling; bandwidth usage spikes |
2 |
Packet Drop Check |
Monitor packet loss under load |
Increased packet drops |
3 |
Latency Spike |
Measure latency during overload |
Latency increases significantly |
4 |
No ACK Handling |
Disable ACK-based flow control |
ACKs ignored; sender keeps sending |
5 |
Buffer Overflow |
Fill receiver buffer rapidly |
Receiver buffer overflows |
6 |
CPU Load Test |
Monitor CPU under high traffic |
CPU usage spikes |
7 |
Memory Leak Check |
Check memory usage over time |
Memory usage increases |
8 |
TCP Window Ignored |
Ignore TCP window size |
Sender sends beyond window size |
9 |
UDP Flood |
Send UDP packets at max rate |
No rate limiting; flood continues |
10 |
Network Saturation |
Saturate network link |
Link fully utilized |
11 |
Jitter Measurement |
Measure jitter under load |
High jitter observed |
12 |
No Retransmission Delay |
Disable retransmission delay |
Immediate retransmissions |
13 |
Queue Length Growth |
Monitor queue length |
Queue grows rapidly |
14 |
No Rate Adaptation |
Disable rate adaptation |
Constant send rate |
15 |
Packet Reordering |
Observe packet order |
Increased reordering |
16 |
No ECN Response |
Ignore ECN flags |
No congestion response |
17 |
Application Crash |
Stress test app |
App may crash under load |
18 |
No Flow Control |
Disable flow control |
Sender overwhelms receiver |
19 |
Bandwidth Starvation |
Compete with other flows |
Other flows starved |
20 |
No Backoff |
Disable exponential backoff |
Continuous retries |
21 |
Packet Duplication |
Check for duplicate packets |
Duplicates increase |
22 |
No RTT Adjustment |
Ignore RTT changes |
RTT not used for control |
23 |
Socket Buffer Overflow |
Fill socket buffer |
Buffer overflows |
24 |
No Congestion Window |
Disable congestion window |
Unlimited sending |
25 |
Network Device Overload |
Overload NIC |
NIC performance degrades |
26 |
No Slow Start |
Disable slow start |
Full rate from start |
27 |
No Fairness |
Compete with TCP flow |
TCP flow suffers |
28 |
No Throttling |
Disable app-level throttling |
App sends at max rate |
29 |
Packet Loss Pattern |
Analyze loss pattern |
Random or bursty losses |
30 |
No Bandwidth Estimation |
Disable bandwidth probing |
No adaptive behavior |
31 |
No Queue Management |
Disable AQM |
Queues fill up |
32 |
No Congestion Feedback |
Ignore feedback |
No rate adjustment |
33 |
No Pacing |
Disable packet pacing |
Bursty traffic |
34 |
No Timeout Handling |
Disable timeout logic |
No retransmission timeout |
35 |
No Flow Isolation |
Multiple flows interfere |
One flow dominates |
36 |
No Prioritization |
All packets equal |
No QoS enforcement |
37 |
No Load Balancing |
Single path used |
Path overloads |
38 |
No Packet Shaping |
Disable shaping |
Irregular traffic pattern |
39 |
No Logging |
Disable congestion logs |
No logs generated |
40 |
No Alerts |
Disable congestion alerts |
No alerts triggered |
41 |
No Retry Limit |
Infinite retries |
Retry storm |
42 |
No Drop Detection |
Ignore drops |
No recovery |
43 |
No Congestion Avoidance |
Disable avoidance logic |
Congestion worsens |
44 |
No Flow Termination |
Keep flow alive |
Flow never ends |
45 |
No Packet Prioritization |
All packets same priority |
Critical packets delayed |
46 |
No Adaptive Timeout |
Fixed timeout |
Inefficient retransmissions |
47 |
No Packet Inspection |
Disable DPI |
No traffic analysis |
48 |
No Rate Monitoring |
Disable rate checks |
Unmonitored traffic |
49 |
No Feedback Loop |
Disable feedback loop |
No control mechanism |
50 |
No Error Correction |
Disable FEC |
Errors not corrected |
Checksum For Error Detection - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Valid Checksum |
Send packet with correct checksum |
Packet accepted |
2 |
Invalid Checksum |
Send packet with incorrect checksum |
Packet discarded |
3 |
Checksum Disabled |
Disable checksum in header |
Packet accepted without validation |
4 |
Corrupted Payload |
Modify payload after checksum |
Checksum mismatch; packet dropped |
5 |
Header Corruption |
Modify header after checksum |
Checksum mismatch; packet dropped |
6 |
Zero Checksum |
Set checksum to zero |
Packet accepted (optional checksum) |
7 |
Checksum Recalculation |
Recalculate checksum after change |
Packet accepted |
8 |
Checksum Verification |
Verify checksum at receiver |
Correct checksum validated |
9 |
Checksum Overflow |
Test checksum overflow handling |
Proper wraparound |
10 |
Checksum Underflow |
Test checksum underflow handling |
Proper wraparound |
11 |
Large Payload |
Send large UDP payload |
Checksum calculated correctly |
12 |
Empty Payload |
Send empty UDP payload |
Valid checksum |
13 |
Fragmented Packet |
Send fragmented UDP packet |
Checksum validated across fragments |
14 |
Reordered Packet |
Reorder fragments |
Checksum mismatch |
15 |
Duplicate Packet |
Send duplicate packet |
Checksum validated |
16 |
Bit Flip in Payload |
Flip bit in payload |
Checksum mismatch |
17 |
Bit Flip in Header |
Flip bit in header |
Checksum mismatch |
18 |
Checksum Tampering |
Manually alter checksum |
Packet dropped |
19 |
IPv4 Checksum |
Validate checksum in IPv4 |
Correct handling |
20 |
IPv6 Checksum |
Validate checksum in IPv6 |
Correct handling |
21 |
Checksum with NAT |
Send packet through NAT |
Checksum recalculated if needed |
22 |
Checksum with VPN |
Send packet through VPN |
Checksum validated |
23 |
Checksum with Firewall |
Send packet through firewall |
Packet dropped if invalid |
24 |
Checksum with Proxy |
Send packet through proxy |
Checksum validated |
25 |
Checksum with Load Balancer |
Send packet through LB |
Checksum validated |
26 |
Checksum with QoS |
Send packet with QoS tag |
Checksum unaffected |
27 |
Checksum with VLAN |
Send packet with VLAN tag |
Checksum validated |
28 |
Checksum with Tunneling |
Send packet through tunnel |
Checksum validated |
29 |
Checksum with Encryption |
Encrypt payload |
Checksum calculated before encryption |
30 |
Checksum with Compression |
Compress payload |
Checksum calculated after compression |
31 |
Checksum with Multicast |
Send multicast packet |
Checksum validated |
32 |
Checksum with Broadcast |
Send broadcast packet |
Checksum validated |
33 |
Checksum with Unicast |
Send unicast packet |
Checksum validated |
34 |
Checksum with Jumbo Frames |
Send jumbo frame |
Checksum validated |
35 |
Checksum with Dropped ACK |
Drop ACK packet |
No impact on checksum |
36 |
Checksum with Retransmission |
Retransmit packet |
Checksum validated again |
37 |
Checksum with Timeout |
Delay packet |
Checksum still valid |
38 |
Checksum with Packet Loss |
Simulate loss |
No checksum validation |
39 |
Checksum with Congestion |
Simulate congestion |
Checksum validated |
40 |
Checksum with High Latency |
Simulate latency |
Checksum validated |
41 |
Checksum with Low Latency |
Fast delivery |
Checksum validated |
42 |
Checksum with Noise |
Add noise to channel |
Checksum detects corruption |
43 |
Checksum with Bit Error Rate |
Simulate BER |
Checksum detects errors |
44 |
Checksum with CRC Comparison |
Compare with CRC |
Checksum less robust |
45 |
Checksum with TCP Comparison |
Compare with TCP checksum |
UDP checksum simpler |
46 |
Checksum with ICMP |
Send ICMP error |
Checksum validated |
47 |
Checksum with ARP |
Send ARP request |
No checksum in ARP |
48 |
Checksum with DNS |
Send DNS over UDP |
Checksum validated |
49 |
Checksum with DHCP |
Send DHCP packet |
Checksum validated |
50 |
Checksum with SNMP |
Send SNMP over UDP |
Checksum validated |
Supports Multicast And Broadcast - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Send Broadcast Packet |
Send UDP packet to broadcast address |
All devices on subnet receive packet |
2 |
Send Multicast Packet |
Send UDP packet to multicast group |
All group members receive packet |
3 |
Join Multicast Group |
Client joins multicast group |
Client receives multicast packets |
4 |
Leave Multicast Group |
Client leaves multicast group |
Client stops receiving packets |
5 |
Broadcast on Local Subnet |
Broadcast within subnet |
Only local subnet devices receive |
6 |
Broadcast Outside Subnet |
Attempt broadcast outside subnet |
Packet not forwarded |
7 |
Multicast TTL = 1 |
Set TTL to 1 |
Packet not forwarded beyond local network |
8 |
Multicast TTL > 1 |
Set TTL > 1 |
Packet forwarded across routers |
9 |
Broadcast with Firewall |
Send with firewall enabled |
Packet blocked if not allowed |
10 |
Multicast with Firewall |
Send with firewall enabled |
Packet blocked if not allowed |
11 |
Broadcast with NAT |
Send through NAT |
Packet may be dropped or altered |
12 |
Multicast with NAT |
Send through NAT |
Multicast may not be supported |
13 |
Broadcast with VLAN |
Send on VLAN |
Packet limited to VLAN scope |
14 |
Multicast with VLAN |
Send on VLAN |
Packet limited to VLAN scope |
15 |
Broadcast Packet Size |
Send large broadcast packet |
Packet fragmented or dropped |
16 |
Multicast Packet Size |
Send large multicast packet |
Packet fragmented or dropped |
17 |
Broadcast Packet Loss |
Simulate loss |
Some devices may not receive |
18 |
Multicast Packet Loss |
Simulate loss |
Some group members miss packet |
19 |
Broadcast Packet Delay |
Introduce delay |
All devices receive with delay |
20 |
Multicast Packet Delay |
Introduce delay |
Group members receive with delay |
21 |
Broadcast Packet Duplication |
Duplicate packet |
Devices receive multiple copies |
22 |
Multicast Packet Duplication |
Duplicate packet |
Group members receive multiple copies |
23 |
Broadcast with QoS |
Apply QoS |
Packet prioritized or deprioritized |
24 |
Multicast with QoS |
Apply QoS |
Packet prioritized or deprioritized |
25 |
Broadcast with Encryption |
Encrypt payload |
Devices must decrypt |
26 |
Multicast with Encryption |
Encrypt payload |
Group members must decrypt |
27 |
Broadcast with Authentication |
Add auth header |
Devices validate sender |
28 |
Multicast with Authentication |
Add auth header |
Group members validate sender |
29 |
Broadcast with Logging |
Enable logging |
Packet logged on all receivers |
30 |
Multicast with Logging |
Enable logging |
Packet logged on group members |
31 |
Broadcast with Packet Sniffer |
Use sniffer |
Packet visible on network |
32 |
Multicast with Packet Sniffer |
Use sniffer |
Packet visible to group only |
33 |
Broadcast with Packet Tampering |
Modify packet |
Receivers detect corruption |
34 |
Multicast with Packet Tampering |
Modify packet |
Group detects corruption |
35 |
Broadcast with High Traffic |
Send many packets |
Network congestion possible |
36 |
Multicast with High Traffic |
Send many packets |
Group congestion possible |
37 |
Broadcast with Low Bandwidth |
Limit bandwidth |
Packet loss or delay |
38 |
Multicast with Low Bandwidth |
Limit bandwidth |
Packet loss or delay |
39 |
Broadcast with Multiple Interfaces |
Send from multiple NICs |
Packet sent on all interfaces |
40 |
Multicast with Multiple Interfaces |
Send from multiple NICs |
Packet sent on selected interface |
41 |
Broadcast with Loopback |
Send to loopback |
Packet not broadcasted |
42 |
Multicast with Loopback |
Send to loopback |
Packet not multicast |
43 |
Broadcast with IPv6 |
Use IPv6 broadcast |
Not supported (use multicast) |
44 |
Multicast with IPv6 |
Use IPv6 multicast |
Packet delivered to group |
45 |
Broadcast with Socket Reuse |
Reuse socket |
Multiple apps receive |
46 |
Multicast with Socket Reuse |
Reuse socket |
Multiple apps receive |
47 |
Broadcast with TTL |
Set TTL |
TTL ignored for broadcast |
48 |
Multicast with Interface Binding |
Bind to interface |
Packet sent on bound interface |
49 |
Broadcast with Port Conflict |
Use same port |
Conflict or shared delivery |
50 |
Multicast with Port Conflict |
Use same port |
Conflict or shared delivery |
Lightweight Header - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Basic Header Validation |
Check standard UDP header fields |
All fields present and correct |
2 |
Header Size Check |
Measure UDP header size |
Exactly 8 bytes |
3 |
No Extra Fields |
Ensure no additional header fields |
Only source port, dest port, length, checksum |
4 |
Header Parsing |
Parse header at receiver |
Successful parsing |
5 |
Header Corruption |
Corrupt header bits |
Packet dropped |
6 |
Header Compression |
Attempt compression |
No effect; already minimal |
7 |
Header Expansion Attempt |
Add extra fields |
Packet rejected |
8 |
Header with IPv4 |
Send over IPv4 |
8-byte UDP header used |
9 |
Header with IPv6 |
Send over IPv6 |
8-byte UDP header used |
10 |
Header with Fragmentation |
Fragment packet |
Header remains intact per fragment |
11 |
Header with NAT |
Send through NAT |
Header translated correctly |
12 |
Header with Firewall |
Send through firewall |
Header inspected correctly |
13 |
Header with VPN |
Send through VPN |
Header preserved |
14 |
Header with VLAN |
Send on VLAN |
Header unaffected |
15 |
Header with QoS |
Apply QoS |
Header remains unchanged |
16 |
Header with Encryption |
Encrypt payload |
Header not encrypted |
17 |
Header with Compression |
Compress payload |
Header not compressed |
18 |
Header with Broadcast |
Send broadcast |
Header used as-is |
19 |
Header with Multicast |
Send multicast |
Header used as-is |
20 |
Header with Loopback |
Send to loopback |
Header parsed correctly |
21 |
Header with Socket Reuse |
Reuse socket |
Header reused correctly |
22 |
Header with Port Conflict |
Use same port |
Header identifies correct flow |
23 |
Header with Checksum |
Validate checksum field |
Correct checksum |
24 |
Header with Zero Checksum |
Set checksum to zero |
Packet accepted (optional) |
25 |
Header with Invalid Checksum |
Corrupt checksum |
Packet dropped |
26 |
Header with Large Payload |
Send large payload |
Header handles size correctly |
27 |
Header with Empty Payload |
Send empty payload |
Header still valid |
28 |
Header with TTL |
TTL in IP header only |
UDP header unaffected |
29 |
Header with ICMP Error |
Trigger ICMP error |
Header used for error reporting |
30 |
Header with DNS |
Send DNS over UDP |
Header used correctly |
31 |
Header with DHCP |
Send DHCP over UDP |
Header used correctly |
32 |
Header with SNMP |
Send SNMP over UDP |
Header used correctly |
33 |
Header with RTP |
Send RTP over UDP |
Header used correctly |
34 |
Header with SIP |
Send SIP over UDP |
Header used correctly |
35 |
Header with TFTP |
Send TFTP over UDP |
Header used correctly |
36 |
Header with NTP |
Send NTP over UDP |
Header used correctly |
37 |
Header with Custom Protocol |
Send custom UDP payload |
Header used correctly |
38 |
Header with Bit Flip |
Flip bit in header |
Packet dropped |
39 |
Header with Delay |
Delay packet |
Header still valid |
40 |
Header with Jitter |
Introduce jitter |
Header unaffected |
41 |
Header with Packet Loss |
Simulate loss |
Header not recovered |
42 |
Header with Retransmission |
Retransmit packet |
Header reused |
43 |
Header with Logging |
Log header fields |
All fields logged correctly |
44 |
Header with Monitoring Tool |
Use sniffer |
Header visible and correct |
45 |
Header with Load Balancer |
Send through LB |
Header used for routing |
46 |
Header with Proxy |
Send through proxy |
Header preserved |
47 |
Header with Bitrate Control |
Control bitrate |
Header unaffected |
48 |
Header with Interface Binding |
Bind to interface |
Header used correctly |
49 |
Header with IPv6 Extension |
Use IPv6 extension headers |
UDP header remains 8 bytes |
50 |
Header with Header Analyzer |
Use analyzer tool |
Header fields correctly identified |
Port Numbers - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Valid Port Range |
Use port number between 065535 |
Packet accepted |
2 |
Reserved Port Usage |
Use reserved port (e.g., 53 for DNS) |
Packet routed to correct service |
3 |
Invalid Port Number |
Use port > 65535 |
Packet rejected |
4 |
Negative Port Number |
Use negative port |
Packet rejected |
5 |
Port Number Zero |
Use port 0 |
Packet accepted (source only) |
6 |
Port Conflict |
Use same port for multiple apps |
Apps may share or conflict |
7 |
Dynamic Port Allocation |
Use ephemeral port |
Port assigned dynamically |
8 |
Static Port Assignment |
Assign fixed port |
Packet routed correctly |
9 |
Port Reuse |
Enable socket reuse |
Multiple apps receive packet |
10 |
Port Binding Failure |
Bind to used port |
Binding fails |
11 |
Port Binding Success |
Bind to free port |
Binding succeeds |
12 |
Port Filtering |
Block specific port via firewall |
Packet dropped |
13 |
Port Forwarding |
Forward port via NAT |
Packet redirected correctly |
14 |
Port Scanning Detection |
Scan ports |
Detection triggered |
15 |
Port Range Scan |
Scan range of ports |
All open ports identified |
16 |
Port with Broadcast |
Send to broadcast address |
Packet sent to all on port |
17 |
Port with Multicast |
Send to multicast group |
Packet received by group on port |
18 |
Port with Loopback |
Send to loopback |
Packet received locally |
19 |
Port with IPv6 |
Use port with IPv6 |
Packet routed correctly |
20 |
Port with IPv4 |
Use port with IPv4 |
Packet routed correctly |
21 |
Port with DNS |
Use port 53 |
DNS service responds |
22 |
Port with DHCP |
Use port 67/68 |
DHCP service responds |
23 |
Port with SNMP |
Use port 161 |
SNMP service responds |
24 |
Port with TFTP |
Use port 69 |
TFTP service responds |
25 |
Port with NTP |
Use port 123 |
NTP service responds |
26 |
Port with RTP |
Use port 5004 |
RTP stream received |
27 |
Port with SIP |
Use port 5060 |
SIP service responds |
28 |
Port with Custom App |
Use custom port |
App receives packet |
29 |
Port with Logging |
Log port usage |
Port logged correctly |
30 |
Port with Monitoring Tool |
Use sniffer |
Port visible in capture |
31 |
Port with Encryption |
Encrypt payload |
Port remains visible |
32 |
Port with Compression |
Compress payload |
Port unaffected |
33 |
Port with NAT Traversal |
Use STUN/TURN |
Port mapped correctly |
34 |
Port with VPN |
Send through VPN |
Port preserved |
35 |
Port with VLAN |
Send on VLAN |
Port used correctly |
36 |
Port with QoS |
Apply QoS |
Port used for classification |
37 |
Port with Load Balancer |
Send through LB |
Port used for routing |
38 |
Port with Proxy |
Send through proxy |
Port preserved or translated |
39 |
Port with TTL |
TTL in IP header |
Port unaffected |
40 |
Port with Fragmentation |
Fragment packet |
Port info in each fragment |
41 |
Port with Delay |
Delay packet |
Port info preserved |
42 |
Port with Packet Loss |
Simulate loss |
Port info lost with packet |
43 |
Port with Retransmission |
Retransmit packet |
Port info reused |
44 |
Port with Bit Flip |
Flip bit in port field |
Packet misrouted or dropped |
45 |
Port with Header Tampering |
Modify header |
Port info corrupted |
46 |
Port with Logging Disabled |
Disable logging |
Port info not recorded |
47 |
Port with High Traffic |
Send many packets |
Port handles load |
48 |
Port with Low Traffic |
Send few packets |
Port remains open |
49 |
Port with Timeout |
Idle port |
Port may close |
50 |
Port with Error Handling |
Send to closed port |
ICMP error returned |
Stateless Communication - Testcases
S.No |
Test Case |
Description |
Expected Result |
|---|---|---|---|
1 |
Valid Port Range |
Use port number between 065535 |
Packet accepted |
2 |
Reserved Port Usage |
Use reserved port (e.g., 53 for DNS) |
Packet routed to correct service |
3 |
Invalid Port Number |
Use port > 65535 |
Packet rejected |
4 |
Negative Port Number |
Use negative port |
Packet rejected |
5 |
Port Number Zero |
Use port 0 |
Packet accepted (source only) |
6 |
Port Conflict |
Use same port for multiple apps |
Apps may share or conflict |
7 |
Dynamic Port Allocation |
Use ephemeral port |
Port assigned dynamically |
8 |
Static Port Assignment |
Assign fixed port |
Packet routed correctly |
9 |
Port Reuse |
Enable socket reuse |
Multiple apps receive packet |
10 |
Port Binding Failure |
Bind to used port |
Binding fails |
11 |
Port Binding Success |
Bind to free port |
Binding succeeds |
12 |
Port Filtering |
Block specific port via firewall |
Packet dropped |
13 |
Port Forwarding |
Forward port via NAT |
Packet redirected correctly |
14 |
Port Scanning Detection |
Scan ports |
Detection triggered |
15 |
Port Range Scan |
Scan range of ports |
All open ports identified |
16 |
Port with Broadcast |
Send to broadcast address |
Packet sent to all on port |
17 |
Port with Multicast |
Send to multicast group |
Packet received by group on port |
18 |
Port with Loopback |
Send to loopback |
Packet received locally |
19 |
Port with IPv6 |
Use port with IPv6 |
Packet routed correctly |
20 |
Port with IPv4 |
Use port with IPv4 |
Packet routed correctly |
21 |
Port with DNS |
Use port 53 |
DNS service responds |
22 |
Port with DHCP |
Use port 67/68 |
DHCP service responds |
23 |
Port with SNMP |
Use port 161 |
SNMP service responds |
24 |
Port with TFTP |
Use port 69 |
TFTP service responds |
25 |
Port with NTP |
Use port 123 |
NTP service responds |
26 |
Port with RTP |
Use port 5004 |
RTP stream received |
27 |
Port with SIP |
Use port 5060 |
SIP service responds |
28 |
Port with Custom App |
Use custom port |
App receives packet |
29 |
Port with Logging |
Log port usage |
Port logged correctly |
30 |
Port with Monitoring Tool |
Use sniffer |
Port visible in capture |
31 |
Port with Encryption |
Encrypt payload |
Port remains visible |
32 |
Port with Compression |
Compress payload |
Port unaffected |
33 |
Port with NAT Traversal |
Use STUN/TURN |
Port mapped correctly |
34 |
Port with VPN |
Send through VPN |
Port preserved |
35 |
Port with VLAN |
Send on VLAN |
Port used correctly |
36 |
Port with QoS |
Apply QoS |
Port used for classification |
37 |
Port with Load Balancer |
Send through LB |
Port used for routing |
38 |
Port with Proxy |
Send through proxy |
Port preserved or translated |
39 |
Port with TTL |
TTL in IP header |
Port unaffected |
40 |
Port with Fragmentation |
Fragment packet |
Port info in each fragment |
41 |
Port with Delay |
Delay packet |
Port info preserved |
42 |
Port with Packet Loss |
Simulate loss |
Port info lost with packet |
43 |
Port with Retransmission |
Retransmit packet |
Port info reused |
44 |
Port with Bit Flip |
Flip bit in port field |
Packet misrouted or dropped |
45 |
Port with Header Tampering |
Modify header |
Port info corrupted |
46 |
Port with Logging Disabled |
Disable logging |
Port info not recorded |
47 |
Port with High Traffic |
Send many packets |
Port handles load |
48 |
Port with Low Traffic |
Send few packets |
Port remains open |
49 |
Port with Timeout |
Idle port |
Port may close |
50 |
Port with Error Handling |
Send to closed port |
ICMP error returned |
S.No |
UDP Header |
Description |
Size(Bytes) |
Position(bits) |
|---|---|---|---|---|
1 |
Source Port |
Identifies the sending port number. |
2 |
015 |
2 |
Destination Port |
Identifies the receiving port number. |
2 |
1631 |
3 |
Length |
Specifies the length of the UDP header and data. |
2 |
3247 |
4 |
Checksum |
Used for error-checking of the header and data. |
2 |
4863 |
S.No |
Protocol/Application |
Descrption |
|---|---|---|
1 |
DNS (Domain Name System) |
Resolves domain names to IP addresses using fast, connectionless queries. |
2 |
DHCP (Dynamic Host Configuration Protocol) |
Assigns IP addresses and network configuration to devices. |
3 |
TFTP (Trivial File Transfer Protocol) |
A simple protocol for transferring files with minimal overhead. |
4 |
SNMP (Simple Network Management Protocol) |
Monitors and manages network devices like routers and switches. |
5 |
NTP (Network Time Protocol) |
Synchronizes clocks across computer systems over packet-switched networks. |
6 |
RTP (Real-time Transport Protocol) |
Delivers audio and video over IP networks, often used in streaming and VoIP. |
7 |
VoIP (Voice over IP) |
Enables voice communication over the internet with low latency. |
8 |
IPTV (Internet Protocol Television) |
Streams television content over IP networks using multicast UDP. |
9 |
QUIC (Quick UDP Internet Connections) |
A modern transport protocol built on UDP, offering faster and secure connections. |
10 |
Multicast Streaming |
Distributes data to multiple recipients simultaneously, commonly used in live broadcasts. |
S.no |
General Socket-Level Options |
Explanation |
Details |
|---|---|---|---|
1 |
SO_BROADCAST |
SO_BROADCAST is a socket option that allows a UDP socket to send datagrams to broadcast |
Header: <sys/socket.h> |
addresses, such as 192.168.1.255. |
Level: SOL_SOCKET |
||
Purpose |
To enable a socket to transmit messages to all hosts on a subnet using a broadcast address. |
||
|
|||
Type |
This means the option is set using an integer value, but it behaves like a boolean flag. |
Boolean (int) |
|
Values |
0 = Disabled: The socket is not allowed to send datagrams to broadcast addresses |
0 = Disabled, 1 = Enabled |
|
1 = Enabled: The socket is allowed to send to broadcast addresses. |
|||
Default Value |
By default, broadcasting is disabled for security and network efficiency reasons. If you try to send to a broadcast address without enabling this option, the system will return a Permission denied error. |
zero |
|
2 |
SO_REUSEADDR |
SO_REUSEADDR is a socket option that allows multiple sockets to bind to the same local IP |
Header: <sys/socket.h> |
|
Level: SOL_SOCKET |
||
Purpose |
To allow quick reuse of a port after a socket is closed, or to allow multiple sockets to bind to |
||
the same port |
|||
Type |
Though conceptually a boolean, it’s implemented as an integer (0 or 1) in system calls. |
Boolean |
|
values |
0- If a server crashes or is restarted quickly, it may not be able to bind to the same port until |
0 = Disabled (default) |
|
|
1 = Enabled |
||
Default Value |
Reuse is disabled by default to avoid accidental port conflicts. |
0 |
|
3 |
SO_RCVBUF |
SO_RCVBUF is a socket option that sets the size of the receive buffer used by the kernel |
Header: <sys/socket.h> |
for incoming data on a socket. |
Level: SOL_SOCKET |
||
Purpose |
To control how much incoming data can be buffered by the kernel before being read by the |
||
application. Larger buffers help prevent packet loss during bursts. |
|||
Type |
The size of the buffer is specified in bytes. |
Integer (bytes) |
|
Values |
The kernel may double the value internally for overhead. |
Any positive integer |
|
Default Value |
System-dependent (commonly 212992 bytes). |
System-dependent (e.g., 212992) |
|
Can be checked via /proc/sys/net/core/rmem_default. |
|||
4 |
SO_SNDBUF |
SO_SNDBUF is a socket option that sets the size of the send buffer used by the kernel for |
Header: <sys/socket.h> |
outgoing data on a socket. |
Level: SOL_SOCKET |
||
Purpose |
To control how much data can be queued in the kernel before being sent over the network. |
||
Larger buffers help in high-throughput or high-latency networks. |
|||
Type |
The size of the buffer is specified in bytes. |
Integer (bytes) |
|
Values |
Any positive integer |
(e.g., 8192, 65536, 262144, etc.) |
|
Default Value |
System-dependent (commonly 16384 or 212992 bytes). |
System-dependent (e.g., 212992) |
|
Can be checked via /proc/sys/net/core/wmem_default. |
|||
5 |
SO_RCVTIMEO |
SO_RCVTIMEO is a socket option that sets a timeout value for receiving data on a socket. |
Header: <sys/socket.h> |
|
Level: SOL_SOCKET |
||
error. |
|||
Purpose |
To prevent a socket from blocking indefinitely while waiting for incoming data. Useful in |
||
applications that require responsiveness or timeout handling. |
|||
Type |
A structure with two fields: tv_sec (seconds) and tv_usec (microseconds). |
struct timeval |
|
Values |
Any valid struct timeval value |
e.g., tv_sec = 5, tv_usec = 0 sets a 5-second timeout. |
|
Default Value |
The socket will wait indefinitely for data unless a timeout is explicitly set. |
Default: Blocking (no timeout) |
|
6 |
SO_SNDTIMEO |
SO_SNDTIMEO is a socket option that sets a timeout value for sending data on a socket. |
Header: <sys/socket.h> |
If the data cannot be sent within the specified time, the send() or sendto() call will return error. |
Level: SOL_SOCKET |
||
Purpose |
To prevent a socket from blocking indefinitely while trying to send data. Useful in applications that |
||
require responsiveness or timeout handling. |
|||
Type |
A structure with two fields: tv_sec (seconds) and tv_usec (microseconds). |
struct timeval |
|
Values |
Any valid struct timeval value |
tv_sec = 3, tv_usec = 0 sets a 3-second timeout. |
|
Default Value |
The socket will wait indefinitely to send data unless a timeout is explicitly set. |
Default: Blocking (no timeout) |
|
7 |
SO_TIMESTAMP |
SO_TIMESTAMP is a socket option that enables the recording of the arrival time of incoming |
Header: <sys/socket.h> |
datagrams. The timestamp is attached as ancillary data to each received message. |
Level: SOL_SOCKET |
||
Purpose |
To allow applications to retrieve the exact time a datagram was received by the kernel. |
||
|
|||
Type |
Though conceptually a boolean, it’s implemented as an integer (0 or 1). |
Boolean |
|
Values |
When enabled, each received packet includes a timestamp (in struct timeval format) in the control |
0 = Disabled (default) |
|
message metadata. This is accessed via recvmsg() instead of recvfrom(). |
1 = Enabled |
||
Default Value |
Timestamping is disabled by default. |
0 |
|
8 |
IP_MULTICAST_TTL |
IP_MULTICAST_TTL is a socket option that sets the Time-To-Live (TTL) value for outgoing multicast |
Header: <netinet/in.h> |
packets. TTL determines how many network hops a packet can traverse. |
Level: IPPROTO_IP |
||
Purpose |
To control the scope or reach of multicast traffic. A lower TTL restricts packets to the local network; |
||
a higher TTL allows them to travel across multiple routers. |
|||
Type |
The TTL value is an 8-bit integer. |
Integer (0255) |
|
Values |
0 = Restricted to the same host |
0,1,>1 |
|
1 = Restricted to the same subnet |
|||
>1 = Can traverse multiple subnets depending on the value |
|||
Default Value |
By default, multicast packets are limited to the local subnet. |
1 |
|
9 |
IP_MULTICAST_LOOP |
IP_MULTICAST_LOOP is a socket option that controls whether multicast packets sent from a socket |
|
are looped back and received by the same socket on the sending host. |
|||
Purpose |
To allow or prevent the sender from receiving its own multicast transmissions. Useful for testing, |
||
|
|||
Type |
Though conceptually a boolean, it’s implemented as an integer (0 or 1). |
Boolean |
|
Values |
0 =Disabled The sender does not receive its own multicast packets. |
0= Disabled |
|
1 = Enabled The sender does receive its own multicast packets. |
1 = Enabled |
||
Default Value |
Loopback is enabled by default. |
1 |
|
10 |
IP_ADD_MEMBERSHIP |
IP_ADD_MEMBERSHIP is a socket option used to join a multicast group on a specified interface, |
Header: <netinet/in.h> |
enabling the socket to receive multicast traffic sent to that group. |
Level: IPPROTO_IP |
||
Purpose |
To allow a UDP socket to subscribe to a multicast group and receive datagrams addressed to |
||
that group IP. |
|||
Type |
struct ip_mreq A structure containing: |
struct ip_mreq |
|
imr_multiaddr: the multicast group address |
|||
imr_interface: the local interface address to join on |
|||
Values |
A valid ip_mreq structure with: |
(e.g., 239.0.0.1) |
|
|
|
||
|
|||
Default Value |
The socket is not a member of any multicast group by default. |
Not applicable |
|
11 |
IP_DROP_MEMBERSHIP |
A socket option used with setsockopt() to instruct the kernel to leave a multicast group on a |
Header: <netinet/in.h> |
specified interface. |
Level: IPPROTO_IP |
||
Purpose |
Used to leave a multicast group on a specified interface. |
||
Type |
a structure that specifies the multicast group and the local interface. |
struct ip_mreq |
|
Values |
A structure that specifies: |
||
imr_multiaddr: the multicast group IP address to leave |
|||
imr_interface: the local interface IP address |
|||
Default Value |
You must explicitly provide both imr_multiaddr and imr_interface. There is no default multicast |
None |
|
group or interface. |
|||
12 |
IP_PKTINFO |
A socket option that allows an application to receive ancillary data (control messages) containing |
Header: <netinet/in.h> |
the destination IP address, interface index, and local address for incoming IPv4 datagrams. |
Level: IPPROTO_IP |
||
Purpose |
When enabled, the kernel includes a struct in_pktinfo in the control message of received datagrams,which provides metadata about how the packet was received. |
||
Type |
(used with setsockopt() and getsockopt() to enable or disable the option) |
Boolean |
|
Values |
0 (disabled): |
0 (disabled), 1 (enabled) |
|
By default, the socket does not receive extra information like destination address or interface index. |
|||
1 (enabled): |
|||
When set, the socket receives ancillary data with each incoming datagram. This data includes: |
|||
The destination IP address the packet was sent to |
|||
The interface index on which the packet was received |
|||
The local address used to receive the packet |
|||
Default Value |
the socket will not receive any packet metadata like interface or destination address. |
0 |
|
This keeps socket behavior simple and lightweight unless such details are needed. |
|||
13 |
IP_RECVTTL |
A socket option that enables an application to receive the TTL (Time To Live) value of incoming |
Header: <netinet/in.h> |
IPv4 datagrams as ancillary data. |
Level: IPPROTO_IP |
||
Purpose |
Allows a socket to receive the TTL (Time To Live) value of incoming IPv4 datagrams. |
||
Type |
this value to setsockopt() to turn the option on or off. |
Boolean (int) |
|
Values |
0 (disabled): TTL is not received. |
0 Disabled |
|
1 (enabled): TTL is included in the control message (cmsghdr) of received datagrams. |
1 Enabled |
||
Default Value |
By default, the socket does not receive TTL information. This keeps packet processing lightweight |
Default: 0 |
|
unless TTL is explicitly needed. |
|||
14 |
IP_TOS |
IP_TOS is a socket option that allows an application to set the Type of Service (ToS) field in the IP |
Header: <netinet/in.h> |
header of outgoing IPv4 packets. This 8-bit field can influence how routers and network devices handle the packet, based on service preferences like delay, throughput, reliability, or cost. |
Level: IPPROTO_IP |
||
Purpose |
Sets the Type of Service (ToS) field in the IP header of outgoing IPv4 packets. This field can influence |
||
how routers handle the packet |
|||
Type |
each bit or group of bits can represent different service preferences. |
Integer (0255) |
|
Commonly used with DSCP (Differentiated Services Code Point) and ECN |
|||
(Explicit Congestion Notification). |
|||
Values |
These values are set using setsockopt() and are placed in the ToS byte of the IP header. |
0x10 (Low Delay) |
|
The ToS byte has evolved into the DSCP (6 bits) + ECN (2 bits) format in modern networks. |
0x08 (High Throughput) |
||
can combine values using bitwise OR, but in practice, DSCP values are preferred for fine-grained QoS. |
0x04 (High Reliability) |
||
0x02 (Minimize Cost) |
|||
Custom DSCP values |
|||
Default Value |
Default ToS value means no special handling is requested; packets are treated with normal |
Default: 0 |
|
priority and routing behavior |
|||
15 |
IP_RECVTOS |
A socket option that allows an application to receive the Type of Service (ToS) field from the |
Header: <netinet/in.h> |
IP header of incoming IPv4 packets. |
Level: IPPROTO_IP |
||
Purpose |
Enables the application to access the ToS byte (which includes DSCP and ECN bits) from received |
||
packets, useful for diagnostics, QoS monitoring, or routing decisions. |
|||
Type |
this value to setsockopt() to turn the option on or off. |
Boolean (int) |
|
Values |
0 ToS field is not received. |
0 Disabled |
|
1 ToS field is included in the control message (cmsghdr) of incoming datagrams. |
1 Enabled |
||
Default Value |
The socket does not receive ToS information unless explicitly enabled. |
0 Disabled by default |
S.No |
Parameter Name |
Description |
File Path |
|---|---|---|---|
1 |
udp_mem |
Memory thresholds for all UDP sockets: [low, pressure, high] in pages. |
/proc/sys/net/ipv4/udp_mem |
2 |
udp_rmem_min |
Minimum receive buffer size for UDP sockets. |
/proc/sys/net/ipv4/udp_rmem_min |
3 |
udp_wmem_min |
Minimum send buffer size for UDP sockets. |
/proc/sys/net/ipv4/udp_wmem_min |
4 |
udp_l3mdev_accept |
Accept UDP traffic on L3 master devices (e.g., VRFs). |
/proc/sys/net/ipv4/udp_l3mdev_accept |
5 |
udp_early_demux |
Enables early demultiplexing of UDP packets. |
/proc/sys/net/ipv4/udp_early_demux |
6 |
udp_encap_enable |
Enables UDP encapsulation support (e.g., for IPsec or GTP-U). |
/proc/sys/net/ipv4/udp_encap_enable |
7 |
udp_tunnel_nic_info |
Provides information about UDP tunnel NICs. |
/proc/sys/net/ipv4/udp_tunnel_nic_info |
8 |
udp_checksum |
Enables or disables UDP checksumming for IPv4. |
/proc/sys/net/ipv4/udp_checksum |
9 |
udp_no_check6_rx |
Disable checksum verification for incoming IPv6 UDP packets. |
/proc/sys/net/ipv6/udp_no_check6_rx |
10 |
udp_no_check6_tx |
Disable checksum generation for outgoing IPv6 UDP packets. |
/proc/sys/net/ipv6/udp_no_check6_tx |
11 |
udp_port_randomization |
Controls the range of ephemeral ports used by UDP. |
/proc/sys/net/ipv4/ip_local_port_range |
12 |
udp_socket_buffer_limit |
Max receive buffer size for all UDP sockets. |
/proc/sys/net/core/rmem_max |
13 |
udp_socket_send_buffer |
Max send buffer size for all UDP sockets. |
/proc/sys/net/core/wmem_max |
14 |
udp_default_rmem |
Default receive buffer size for UDP sockets. |
/proc/sys/net/core/rmem_default |
15 |
udp_default_wmem |
Default send buffer size for UDP sockets. |
/proc/sys/net/core/wmem_default |
16 |
udp_max_backlog |
Max number of packets in the input queue. |
/proc/sys/net/core/netdev_max_backlog |
17 |
udp_bpf_jit_enable |
Enables BPF JIT for UDP packet filtering. |
/proc/sys/net/core/bpf_jit_enable |
18 |
udp_bpf_jit_harden |
Enables hardening for BPF JIT. |
/proc/sys/net/core/bpf_jit_harden |
19 |
udp_bpf_jit_kallsyms |
Export BPF JIT symbols for debugging. |
/proc/sys/net/core/bpf_jit_kallsyms |
20 |
udp_max_orphans |
Max orphaned sockets (applies to UDP too). |
/proc/sys/net/ipv4/tcp_max_orphans |
21 |
udp_max_qlen |
Max ancillary data (control messages) per socket. |
/proc/sys/net/core/optmem_max |
22 |
udp_fragmentation |
High threshold for IP fragmentation (affects UDP too). |
/proc/sys/net/ipv4/ipfrag_high_thresh |
23 |
udp_fragmentation_low |
Low threshold for IP fragmentation. |
/proc/sys/net/ipv4/ipfrag_low_thresh |
24 |
udp_fragmentation_timeout |
Timeout for IP fragments (in seconds). |
/proc/sys/net/ipv4/ipfrag_time |
25 |
udp_local_port_range |
Range of ephemeral ports used by UDP. |
/proc/sys/net/ipv4/ip_local_port_range |
26 |
udp_autobind_reuse |
Allow reuse of autobound ports. |
/proc/sys/net/ipv4/udp_autobind_reuse |
27 |
udp_queue_rcvbuf_expiry |
Time budget for processing UDP receive queue. |
/proc/sys/net/core/netdev_budget_usecs |
28 |
udp_rcvbuf_pressure |
Pressure threshold for UDP receive buffer. |
/proc/sys/net/core/rmem_pressure |
29 |
udp_sndbuf_pressure |
Pressure threshold for UDP send buffer. |
/proc/sys/net/core/wmem_pressure |
30 |
udp_checksum_offload |
Affects checksum offloading behavior. |
/proc/sys/net/core/dev_weight |
31 |
udp_gro_receive_limit |
Max number of UDP packets processed in GRO batch. |
/proc/sys/net/core/gro_normal_batch_limit |
32 |
udp_gro_flush_timeout |
Timeout for flushing GRO UDP packets. |
/proc/sys/net/core/gro_flush_timeout |
33 |
udp_gso_max_segs |
Max number of segments in a UDP GSO packet. |
/proc/sys/net/core/gso_max_segs |
34 |
udp_gso_max_size |
Max size of a UDP GSO packet. |
/proc/sys/net/core/gso_max_size |
35 |
udp_napi_weight |
NAPI weight for UDP packet processing. |
/proc/sys/net/core/dev_weight |
36 |
udp_napi_budget |
Max number of packets processed per NAPI poll. |
/proc/sys/net/core/netdev_budget |
37 |
udp_napi_budget_usecs |
Time budget for NAPI polling. |
/proc/sys/net/core/netdev_budget_usecs |
38 |
udp_rps_sock_flow_entries |
Number of flow entries for UDP RPS (Receive Packet Steering). |
/proc/sys/net/core/rps_sock_flow_entries |
39 |
udp_rps_cpus |
CPU mask for RPS (affects UDP). |
/proc/sys/net/core/rps_cpus |
40 |
udp_xps_cpus |
CPU mask for XPS (Transmit Packet Steering). |
/proc/sys/net/core/xps_cpus |
41 |
udp_xps_map |
Mapping of queues to CPUs for UDP XPS. |
/proc/sys/net/core/xps_map |
42 |
udp_flow_limit |
Max number of UDP flows tracked. |
/proc/sys/net/core/flow_limit_table_len |
43 |
udp_flow_timeout |
Timeout for UDP flow tracking. |
/proc/sys/net/core/flow_limit_table_timeout |
44 |
udp_flow_gc_interval |
Interval for garbage collecting UDP flows. |
/proc/sys/net/core/flow_limit_gc_interval |
45 |
udp_flow_limit_enable |
Enables UDP flow limiting. |
/proc/sys/net/core/flow_limit_enable |
46 |
udp_flow_limit_burst |
Burst size for UDP flow limiting. |
/proc/sys/net/core/flow_limit_burst |
47 |
udp_flow_limit_rate |
Rate limit for UDP flows. |
/proc/sys/net/core/flow_limit_rate |
48 |
udp_flow_limit_log |
Enables logging for UDP flow limiting. |
/proc/sys/net/core/flow_limit_log |
49 |
udp_flow_limit_log_thresh |
Threshold for logging UDP flow drops. |
/proc/sys/net/core/flow_limit_log_thresh |
50 |
udp_flow_limit_log_burst |
Burst size for UDP flow log messages. |
/proc/sys/net/core/flow_limit_log_burst |
51 |
udp_flow_limit_log_rate |
Rate of UDP flow log messages. |
/proc/sys/net/core/flow_limit_log_rate |
52 |
udp_flow_limit_log_level |
Log level for UDP flow messages. |
/proc/sys/net/core/flow_limit_log_level |
53 |
udp_flow_limit_log_prefix |
Prefix for UDP flow log messages. |
/proc/sys/net/core/flow_limit_log_prefix |
54 |
udp_flow_limit_log_file |
File path for UDP flow logs. |
/proc/sys/net/core/flow_limit_log_file |
55 |
udp_flow_limit_log_format |
Format string for UDP flow logs. |
/proc/sys/net/core/flow_limit_log_format |
56 |
udp_flow_limit_log_flags |
Flags for UDP flow log behavior. |
/proc/sys/net/core/flow_limit_log_flags |
57 |
udp_flow_limit_log_mask |
Mask for filtering UDP flow logs. |
/proc/sys/net/core/flow_limit_log_mask |
58 |
udp_flow_limit_log_filter |
Filter expression for UDP flow logs. |
/proc/sys/net/core/flow_limit_log_filter |
59 |
udp_flow_limit_log_action |
Action to take on UDP flow limit log match. |
/proc/sys/net/core/flow_limit_log_action |
60 |
udp_flow_limit_log_notify |
Notify user-space on UDP flow limit log match. |
/proc/sys/net/core/flow_limit_log_notify |
61 |
udp_autocorking |
Enables automatic corking of small UDP packets to reduce overhead. |
/proc/sys/net/ipv4/udp_autocorking |
62 |
udp_max_segment_size |
Maximum segment size for UDP GSO packets. |
/proc/sys/net/core/udp_max_segment_size |
63 |
udp_gro_enabled |
Enables Generic Receive Offload for UDP. |
/proc/sys/net/core/udp_gro_enabled |
64 |
udp_gso_enabled |
Enables Generic Segmentation Offload for UDP. |
/proc/sys/net/core/udp_gso_enabled |
65 |
udp_gro_flush_interval |
Interval to flush GRO UDP packets (in ms). |
/proc/sys/net/core/udp_gro_flush_interval |
66 |
udp_gso_flush_interval |
Interval to flush GSO UDP packets (in ms). |
/proc/sys/net/core/udp_gso_flush_interval |
67 |
udp_checksum_policy |
Policy for enforcing UDP checksums in IPv6. |
/proc/sys/net/ipv6/udp_checksum_policy |
68 |
udp_zero_checksum_accept |
Accept IPv6 UDP packets with zero checksum. |
/proc/sys/net/ipv6/udp_zero_checksum_accept |
69 |
udp_zero_checksum_transmit |
Transmit IPv6 UDP packets with zero checksum. |
/proc/sys/net/ipv6/udp_zero_checksum_transmit |
70 |
udp_flow_cache_size |
Size of the UDP flow cache. |
/proc/sys/net/core/udp_flow_cache_size |
71 |
udp_flow_cache_timeout |
Timeout for entries in the UDP flow cache. |
/proc/sys/net/core/udp_flow_cache_timeout |
72 |
udp_flow_cache_gc_interval |
Interval for garbage collection of UDP flow cache. |
/proc/sys/net/core/udp_flow_cache_gc_interval |
73 |
udp_flow_cache_enable |
Enables UDP flow cache. |
/proc/sys/net/core/udp_flow_cache_enable |
74 |
udp_flow_cache_log |
Enables logging for UDP flow cache events. |
/proc/sys/net/core/udp_flow_cache_log |
75 |
udp_flow_cache_log_level |
Log level for UDP flow cache messages. |
/proc/sys/net/core/udp_flow_cache_log_level |
76 |
udp_flow_cache_log_prefix |
Prefix for UDP flow cache log messages. |
/proc/sys/net/core/udp_flow_cache_log_prefix |
77 |
udp_flow_cache_log_file |
File path for UDP flow cache logs. |
/proc/sys/net/core/udp_flow_cache_log_file |
78 |
udp_flow_cache_log_format |
Format string for UDP flow cache logs. |
/proc/sys/net/core/udp_flow_cache_log_format |
79 |
udp_flow_cache_log_flags |
Flags for UDP flow cache log behavior. |
/proc/sys/net/core/udp_flow_cache_log_flags |
80 |
udp_flow_cache_log_notify |
Notify user-space on UDP flow cache log match. |
/proc/sys/net/core/udp_flow_cache_log_notify |
Reference links