Check Link Hook

This example demonstrates how to process outgoing NHRP traffic in a scenario using one Tunnel with GRE encapsulation.

Test Marks In NHRP Traffic

Description

In this scenario, a traffic policy was configured to log outgoing NHRP traffic, which is non-IP Layer 3 protocol. The special hook link-out can be used to process these outgoing frames.

Scenario

Step 1: Set the following configuration in DUT0 :

set interfaces ethernet eth0 address 192.168.100.10/24
set interfaces tunnel tun0 address 10.0.0.1/32
set interfaces tunnel tun0 encapsulation gre
set interfaces tunnel tun0 local-address 192.168.100.10
set interfaces tunnel tun0 nhrp
set interfaces tunnel tun0 traffic policy link-in LOG_NHRP
set interfaces tunnel tun0 traffic policy link-out LOG_NHRP
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'
set traffic policy LOG_NHRP rule 1 log prefix NHRP__
set traffic policy LOG_NHRP rule 1 selector NHRP_SEL
set traffic selector NHRP_SEL rule 1 ether-type 8193

Note

NHRP packets use ethertype 8193 (0x2001).

Step 2: Set the following configuration in DUT1 :

set interfaces ethernet eth0 address 192.168.100.20/24
set interfaces tunnel tun0 address 10.0.0.2/32
set interfaces tunnel tun0 encapsulation gre
set interfaces tunnel tun0 local-address 192.168.100.20
set interfaces tunnel tun0 nhrp holdtime 5
set interfaces tunnel tun0 nhrp nhs 10.0.0.1 nbma 192.168.100.10
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 3: Run the command protocols ip show nhrp on DUT0 and check whether the output matches the following regular expressions:

tun0\s+dynamic\s+10\.0\.0\.2

Step 4: Run the command system journal show | cat on DUT0 and check whether the output matches the following regular expressions:

\[NHRP__-1\] ACCEPT IN=tun0 OUT=\w+
\[NHRP__-1\] ACCEPT IN= OUT=tun0

Show output

Jun 03 08:37:28.000287 osdx systemd-timedated[28681]: Changed local time to Wed 2026-06-03 08:37:28 UTC
Jun 03 08:37:28.001827 osdx OSDxCLI[5794]: User 'admin' executed a new command: 'set date 2026-06-03 08:37:28'.
Jun 03 08:37:28.004422 osdx systemd-journald[2255]: Time jumped backwards, rotating.
Jun 03 08:37:28.351757 osdx systemd-journald[2255]: Runtime Journal (/run/log/journal/db6c204474e445bc870656488f91fc69) is 1.9M, max 13.8M, 11.8M free.
Jun 03 08:37:28.352573 osdx systemd-journald[2255]: Received client request to rotate journal, rotating.
Jun 03 08:37:28.352644 osdx systemd-journald[2255]: Vacuuming done, freed 0B of archived journals from /run/log/journal/db6c204474e445bc870656488f91fc69.
Jun 03 08:37:28.361407 osdx OSDxCLI[5794]: User 'admin' executed a new command: 'system journal clear'.
Jun 03 08:37:28.621382 osdx OSDxCLI[5794]: User 'admin' executed a new command: 'system coredump delete all'.
Jun 03 08:37:28.870903 osdx OSDxCLI[5794]: User 'admin' entered the configuration menu.
Jun 03 08:37:28.972758 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces ethernet eth0 address 192.168.100.10/24'.
Jun 03 08:37:29.107468 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-out LOG_NHRP'.
Jun 03 08:37:29.218056 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-in LOG_NHRP'.
Jun 03 08:37:29.354053 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 address 10.0.0.1/32'.
Jun 03 08:37:29.468269 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 encapsulation gre'.
Jun 03 08:37:29.585761 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 local-address 192.168.100.10'.
Jun 03 08:37:29.714160 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 nhrp'.
Jun 03 08:37:29.832941 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 log prefix NHRP__'.
Jun 03 08:37:29.946994 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 selector NHRP_SEL'.
Jun 03 08:37:30.066510 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'set traffic selector NHRP_SEL rule 1 ether-type 8193'.
Jun 03 08:37:30.226134 osdx OSDxCLI[5794]: User 'admin' added a new cfg line: 'show working'.
Jun 03 08:37:30.317241 osdx ubnt-cfgd[28718]: inactive
Jun 03 08:37:30.412785 osdx systemd[1]: Reloading frr.service - FRRouting...
Jun 03 08:37:30.428485 osdx watchfrr[28545]: [NG1AJ-FP2TQ] Terminating on signal
Jun 03 08:37:30.529546 osdx frrinit.sh[28751]: Stopped watchfrr.
Jun 03 08:37:30.530608 osdx frrinit.sh[28751]: Starting watchfrr with command: '  /usr/lib/frr/watchfrr  -d  --min-restart-interval 1 --max-restart-interval 600 --timeout 600 --restart-timeout 600 mgmtd zebra nhrpd staticd'.
Jun 03 08:37:30.537509 osdx watchfrr[28769]: [T83RR-8SM5G] watchfrr 10.6.0 starting: vty@0
Jun 03 08:37:30.537557 osdx watchfrr[28769]: [QDG3Y-BY5TN] mgmtd state -> up : connect succeeded
Jun 03 08:37:30.537578 osdx watchfrr[28769]: [QDG3Y-BY5TN] zebra state -> up : connect succeeded
Jun 03 08:37:30.537610 osdx watchfrr[28769]: [ZCJ3S-SPH5S] nhrpd state -> down : initial connection attempt failed
Jun 03 08:37:30.537612 osdx watchfrr[28769]: [QDG3Y-BY5TN] staticd state -> up : connect succeeded
Jun 03 08:37:30.537769 osdx watchfrr[28769]: [YFT0P-5Q5YX] Forked background command [pid 28770]: /usr/lib/frr/watchfrr.sh restart nhrpd
Jun 03 08:37:30.541718 osdx frrinit.sh[28770]: Cannot stop nhrpd: pid file not found
Jun 03 08:37:30.542666 osdx watchfrr.sh[28775]: Cannot stop nhrpd: pid file not found
Jun 03 08:37:30.556993 osdx zebra[1839]: [V98V0-MTWPF] client 41 says hello and bids fair to announce only nhrp routes vrf=0
Jun 03 08:37:30.566890 osdx frrinit.sh[28780]: sh: line 1: ipsec: command not found
Jun 03 08:37:30.579219 osdx nhrpd[28777]: [W9E3X-A5P3X] nhrpd: set-config-loaded received, marking as loaded
Jun 03 08:37:30.580273 osdx watchfrr[28769]: [QDG3Y-BY5TN] nhrpd state -> up : connect succeeded
Jun 03 08:37:30.580280 osdx watchfrr[28769]: [KWE5Q-QNGFC] all daemons up, doing startup-complete notify
Jun 03 08:37:30.580807 osdx frrinit.sh[28751]: Started watchfrr.
Jun 03 08:37:30.688923 osdx systemd[1]: Reloaded frr.service - FRRouting.
Jun 03 08:37:30.724421 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
Jun 03 08:37:30.791504 osdx WARNING[28876]: No supported link modes on interface eth0
Jun 03 08:37:30.793027 osdx modulelauncher[28876]: osdx.utils.xos cmd error: /sbin/ethtool -A eth0 autoneg on
Jun 03 08:37:30.793042 osdx modulelauncher[28876]: Command '/sbin/ethtool -A eth0 autoneg on' returned non-zero exit status 76.
Jun 03 08:37:30.794754 osdx modulelauncher[28876]: osdx.utils.xos cmd error: /sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --
Jun 03 08:37:30.794767 osdx modulelauncher[28876]: Command '/sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --' returned non-zero exit status 75.
Jun 03 08:37:30.824734 osdx (udev-worker)[28902]: Network interface NamePolicy= disabled on kernel command line.
Jun 03 08:37:31.316305 osdx cfgd[1899]: [5794]Completed change to active configuration
Jun 03 08:37:31.316842 osdx OSDxCLI[5794]: User 'admin' committed the configuration.
Jun 03 08:37:31.333287 osdx OSDxCLI[5794]: User 'admin' left the configuration menu.
Jun 03 08:37:33.141857 osdx OSDxCLI[5794]: User 'admin' executed a new command: 'protocols ip show nhrp'.
Jun 03 08:37:33.860421 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:e9:c4:40:00:40:2f:07:27:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Jun 03 08:37:33.860508 osdx kernel: [NHRP__-1] ACCEPT IN= OUT=tun0 MAC=45:01:00:00:00:00:40:00:40:2f:00:00:c0:a8:64:0a:c0:a8:64:14:00:00:20:01
Jun 03 08:37:33.860519 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT=eth0 MAC=00:01:08:00:00:00:00:00:00:40:00:70:2b:43:00:34:01:04:04:00:04:04:00:02
Jun 03 08:37:34.860154 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:ea:98:40:00:40:2f:06:53:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Jun 03 08:37:34.860426 osdx kernel: [NHRP__-1] ACCEPT IN= OUT=tun0 MAC=45:01:00:00:00:00:40:00:40:2f:00:00:c0:a8:64:0a:c0:a8:64:14:00:00:20:01
Jun 03 08:37:34.860468 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT=eth0 MAC=00:01:08:00:00:00:00:00:00:40:00:70:2b:42:00:34:01:04:04:00:04:04:00:02
Jun 03 08:37:35.214484 osdx OSDxCLI[5794]: User 'admin' executed a new command: 'protocols ip show nhrp'.

Step 5: Run the command traffic policy show on DUT0 and check whether the output matches the following regular expressions:

1\s+NHRP_SEL\s+\b[^0]\d*