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Check Link Hook

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

../../../../../_images/topology26.svg

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 command protocols ip show nhrp at DUT0 and check if output matches the following regular expressions:

tun0\s+dynamic\s+10\.0\.0\.2
Show output
Iface      Type     Protocol         NBMA             Claimed NBMA     Expires(s)   Flags  Identity
tun0       local    10.0.0.1         192.168.100.10   192.168.100.10   -                   -
tun0       dynamic  10.0.0.2         192.168.100.20   192.168.100.20   5            UT

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

\[NHRP__-1\] ACCEPT IN=tun0 OUT=\w+
\[NHRP__-1\] ACCEPT IN= OUT=tun0
Show output
Jan 27 16:15:58.000406 osdx systemd-timedated[666619]: Changed local time to Tue 2026-01-27 16:15:58 UTC
Jan 27 16:15:58.001109 osdx systemd-journald[1949]: Time jumped backwards, rotating.
Jan 27 16:15:58.001851 osdx OSDxCLI[647697]: User 'admin' executed a new command: 'set date 2026-01-27 16:15:58'.
Jan 27 16:15:58.336141 osdx systemd-journald[1949]: Runtime Journal (/run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4) is 3.4M, max 13.8M, 10.3M free.
Jan 27 16:15:58.336815 osdx systemd-journald[1949]: Received client request to rotate journal, rotating.
Jan 27 16:15:58.336865 osdx systemd-journald[1949]: Vacuuming done, freed 0B of archived journals from /run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4.
Jan 27 16:15:58.347462 osdx OSDxCLI[647697]: User 'admin' executed a new command: 'system journal clear'.
Jan 27 16:15:58.617293 osdx OSDxCLI[647697]: User 'admin' executed a new command: 'system coredump delete all'.
Jan 27 16:15:58.881239 osdx OSDxCLI[647697]: User 'admin' entered the configuration menu.
Jan 27 16:15:58.995040 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces ethernet eth0 address 192.168.100.10/24'.
Jan 27 16:15:59.065913 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-out LOG_NHRP'.
Jan 27 16:15:59.166056 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-in LOG_NHRP'.
Jan 27 16:15:59.241413 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 address 10.0.0.1/32'.
Jan 27 16:15:59.335438 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 encapsulation gre'.
Jan 27 16:15:59.398818 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 local-address 192.168.100.10'.
Jan 27 16:15:59.490983 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 nhrp'.
Jan 27 16:15:59.546456 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 log prefix NHRP__'.
Jan 27 16:15:59.657943 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 selector NHRP_SEL'.
Jan 27 16:15:59.719267 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'set traffic selector NHRP_SEL rule 1 ether-type 8193'.
Jan 27 16:15:59.951243 osdx OSDxCLI[647697]: User 'admin' added a new cfg line: 'show working'.
Jan 27 16:16:00.026270 osdx ubnt-cfgd[666656]: inactive
Jan 27 16:16:00.093067 osdx systemd[1]: Reloading frr.service - FRRouting...
Jan 27 16:16:00.107009 osdx watchfrr[666459]: [NG1AJ-FP2TQ] Terminating on signal
Jan 27 16:16:00.207829 osdx frrinit.sh[666686]: Stopped watchfrr.
Jan 27 16:16:00.208725 osdx frrinit.sh[666686]: Starting watchfrr with command: '  /usr/lib/frr/watchfrr  -d  --min-restart-interval 1 --max-restart-interval 600 --timeout 600 --restart-timeout 600 zebra mgmtd nhrpd staticd'.
Jan 27 16:16:00.214736 osdx watchfrr[666704]: [T83RR-8SM5G] watchfrr 10.4.1 starting: vty@0
Jan 27 16:16:00.214791 osdx watchfrr[666704]: [QDG3Y-BY5TN] zebra state -> up : connect succeeded
Jan 27 16:16:00.214813 osdx watchfrr[666704]: [QDG3Y-BY5TN] mgmtd state -> up : connect succeeded
Jan 27 16:16:00.214845 osdx watchfrr[666704]: [ZCJ3S-SPH5S] nhrpd state -> down : initial connection attempt failed
Jan 27 16:16:00.214848 osdx watchfrr[666704]: [QDG3Y-BY5TN] staticd state -> up : connect succeeded
Jan 27 16:16:00.215261 osdx watchfrr[666704]: [YFT0P-5Q5YX] Forked background command [pid 666705]: /usr/lib/frr/watchfrr.sh restart nhrpd
Jan 27 16:16:00.219012 osdx frrinit.sh[666705]: Cannot stop nhrpd: pid file not found
Jan 27 16:16:00.220108 osdx watchfrr.sh[666710]: Cannot stop nhrpd: pid file not found
Jan 27 16:16:00.229840 osdx zebra[528496]: [V98V0-MTWPF] client 36 says hello and bids fair to announce only nhrp routes vrf=0
Jan 27 16:16:00.239297 osdx frrinit.sh[666715]: sh: line 1: ipsec: command not found
Jan 27 16:16:00.240181 osdx watchfrr[666704]: [QDG3Y-BY5TN] nhrpd state -> up : connect succeeded
Jan 27 16:16:00.240190 osdx watchfrr[666704]: [KWE5Q-QNGFC] all daemons up, doing startup-complete notify
Jan 27 16:16:00.240697 osdx frrinit.sh[666686]: Started watchfrr.
Jan 27 16:16:00.334411 osdx systemd[1]: Reloaded frr.service - FRRouting.
Jan 27 16:16:00.368828 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
Jan 27 16:16:00.409519 osdx WARNING[666808]: No supported link modes on interface eth0
Jan 27 16:16:00.410912 osdx modulelauncher[666808]: osdx.utils.xos cmd error: /sbin/ethtool -A eth0 autoneg on
Jan 27 16:16:00.410925 osdx modulelauncher[666808]: Command '/sbin/ethtool -A eth0 autoneg on' returned non-zero exit status 76.
Jan 27 16:16:00.411994 osdx modulelauncher[666808]: osdx.utils.xos cmd error: /sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --
Jan 27 16:16:00.412001 osdx modulelauncher[666808]: Command '/sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --' returned non-zero exit status 75.
Jan 27 16:16:00.433374 osdx (udev-worker)[666836]: Network interface NamePolicy= disabled on kernel command line.
Jan 27 16:16:00.694650 osdx cfgd[1624]: [647697]Completed change to active configuration
Jan 27 16:16:00.710140 osdx OSDxCLI[647697]: User 'admin' committed the configuration.
Jan 27 16:16:00.727585 osdx OSDxCLI[647697]: User 'admin' left the configuration menu.
Jan 27 16:16:02.391757 osdx OSDxCLI[647697]: User 'admin' executed a new command: 'protocols ip show nhrp'.
Jan 27 16:16:03.268671 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:61:c5:40:00:40:2f:8f:26:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Jan 27 16:16:03.268842 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
Jan 27 16:16:03.268856 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
Jan 27 16:16:04.269406 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:62:9b:40:00:40:2f:8e:50:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Jan 27 16:16:04.269492 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
Jan 27 16:16:04.269505 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
Jan 27 16:16:04.475684 osdx OSDxCLI[647697]: User 'admin' executed a new command: 'protocols ip show nhrp'.

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

1\s+NHRP_SEL\s+\b[^0]\d*
Show output
Policy LOG_NHRP -- ifc tun0 -- hook link-in prio very-high

---------------------------------------------------------------
rule   selector  pkts match  pkts eval  bytes match  bytes eval
---------------------------------------------------------------
1      NHRP_SEL           4          4          456         456
---------------------------------------------------------------
Total                     4          4          456         456

Policy LOG_NHRP -- ifc tun0 -- hook link-out prio very-high

---------------------------------------------------------------
rule   selector  pkts match  pkts eval  bytes match  bytes eval
---------------------------------------------------------------
1      NHRP_SEL           2          2          272         272
---------------------------------------------------------------
Total                     2          2          272         272
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