Q2-Add SSID IE

Topics in this section,

  • In this section, you are going to learn

  • How to add multiple SSID IE elements in Beacons

#

Version

Ubuntu

Ubuntu 22.04 64 bit

Linux Kernel

6.9.2

Hostapd

hostapd 2.10

  • Add multiple SSID IE elements in Beacons

  • Call flow for add multiple ssid ie in Beacons

main ()
   hostapd_setup_interface ()
     setup_interface ()
       setup_interface2 ()
	 hostapd_setup_interface_complete ()
	   hostapd_setup_interface_complete_sync ()
	     hostapd_setup_bss ()
	      ieee802_11_set_beacon ()
		__ieee802_11_set_beacon ()
		    ieee802_11_build_ap_params ()
		       ap_add_multiple_ssid_ie ()

  • Download the below patch file

add_multiple_ssid_ie_beacons.patch

See the full content of patch file
diff -crB original/hostapd-2.10/src/ap/beacon.c changed/hostapd-2.10/src/ap/beacon.c
*** original/hostapd-2.10/src/ap/beacon.c	2022-01-17 02:21:29.000000000 +0530
--- changed/hostapd-2.10/src/ap/beacon.c	2024-07-25 19:09:48.461444824 +0530
***************
*** 1515,1520 ****
--- 1515,1521 ----
  			  hapd->conf->ssid.ssid_len);
  		pos += hapd->conf->ssid.ssid_len;
  	}
+ 	pos = ap_add_multiple_ssid_ie(pos);
  
  	/* Supported rates */
  	pos = hostapd_eid_supp_rates(hapd, pos);
diff -crB original/hostapd-2.10/src/ap/ieee802_11.h changed/hostapd-2.10/src/ap/ieee802_11.h
*** original/hostapd-2.10/src/ap/ieee802_11.h	2022-01-17 02:21:29.000000000 +0530
--- changed/hostapd-2.10/src/ap/ieee802_11.h	2024-07-25 19:09:09.653445426 +0530
***************
*** 115,120 ****
--- 115,121 ----
  u8 * hostapd_eid_adv_proto(struct hostapd_data *hapd, u8 *eid);
  u8 * hostapd_eid_roaming_consortium(struct hostapd_data *hapd, u8 *eid);
  u8 * hostapd_eid_time_adv(struct hostapd_data *hapd, u8 *eid);
+ u8 * ap_add_multiple_ssid_ie(u8 *eid);
  u8 * hostapd_eid_time_zone(struct hostapd_data *hapd, u8 *eid);
  int hostapd_update_time_adv(struct hostapd_data *hapd);
  void hostapd_client_poll_ok(struct hostapd_data *hapd, const u8 *addr);
diff -crB original/hostapd-2.10/src/ap/ieee802_11_shared.c changed/hostapd-2.10/src/ap/ieee802_11_shared.c
*** original/hostapd-2.10/src/ap/ieee802_11_shared.c	2022-01-17 02:21:29.000000000 +0530
--- changed/hostapd-2.10/src/ap/ieee802_11_shared.c	2024-07-25 19:09:01.413445554 +0530
***************
*** 625,630 ****
--- 625,651 ----
  	return eid;
  }
  
+ char data_ssid1_ie[] = "Hello";
+ char data_ssid2_ie[] = "World";
+ 
+ u8 * ap_add_multiple_ssid_ie(u8 *eid)
+ {
+ 	size_t len;
+ 
+ 	len = os_strlen(data_ssid1_ie);
+         *eid++ = WLAN_EID_SSID;
+         *eid++ = len;
+         os_memcpy(eid, data_ssid1_ie, len);
+         eid += len;
+ 
+ 	len = os_strlen(data_ssid2_ie);
+         *eid++ = WLAN_EID_SSID;
+         *eid++ = len;
+         os_memcpy(eid, data_ssid2_ie, len);
+         eid += len;
+ 
+ 	return eid;
+ }
  
  u8 * hostapd_eid_time_zone(struct hostapd_data *hapd, u8 *eid)
  {

test:~$ pwd
/home/test

  • Make sure internet is available in laptop to download hostapd package

test:~$ sudo wget http://w1.fi/releases/hostapd-2.10.tar.gz

  • Create a directory

test:~$ mkdir hostapd

  • Change directory to hostapd

test:~$ cd hostapd

  • Note : Your present working directory should be hostapd

test:~$ pwd
/home/test/hostapd/

  • Extract hostapd

test:~$ sudo tar -xvf ~/hostapd-2.10.tar.gz

  • Run the below command to apply patch

test:~$ patch -p1 < add_multiple_ssid_ie_beacons.patch
patching file hostapd-2.10/src/ap/beacon.c
patching file hostapd-2.10/src/ap/ieee802_11.h
patching file hostapd-2.10/src/ap/ieee802_11_shared.c

  • Change directory to hostapd

test:~$ cd hostapd-2.10/hostapd/

  • Check the current working directory using pwd command

  • Make sure your current working directory is hostapd

test:~$ pwd
/home/test/hostapd/hostapd-2.10/hostapd/

  • Copy the contents of defconfig file to .config file

test:~$ sudo cp defconfig .config

  • Compile hostapd

test:~$ sudo make

  • Create run_hostapd.conf

test:~$ sudo vim ./run_hostapd.conf

ctrl_interface=/run/hostapd
interface=wlan0
driver=nl80211
ssid=test_open
hw_mode=g
channel=6
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0

  • Run hostapd

test:~$ sudo ./hostapd ./run_hostapd.conf

  • Download file to check wireshark output

add_multiple_ssid_ie_beacons.pcapng

  • Check for beacon packet

  • Click on packet No.2 as shown in the image below

Diagram

  • Click on IEEE 802.11 Wireless Management

  • Click on Tagged parameters

  • Click on Tag: SSID parameter set: Undecoded

Diagram