DHCP server failover - documentation issue

Hi there,

Recently was working on DHCP server failover on two VYOS 1.3 routers.
Just to check decided to see how primary and secondary servers communicate with each other.

Have found no traffic on TCP 647 port as stated in documentation while 520 port is alive and working.

DHCP Server — VyOS 1.3.x (equuleus) documentation


In order for the primary and the secondary DHCP server to keep their lease tables in sync, they must be able to reach each other on TCP port 647. If you have firewall rules in effect, adjust them accordingly.

Just curious is it documentation or configuration bug?


you are right , it seems a error in our configuration on dhcp’s daemon , I’ll create a task on phabricator and share .

vyos@vyos:~$ sudo ss -tulpn | grep 520
udp   UNCONN 0      0      [fe80::5200:ff:fe01:3]%eth3:123            [::]:*     users:(("ntpd",pid=1479,fd=27))
udp   UNCONN 0      0      [fe80::5200:ff:fe01:2]%eth2:123            [::]:*     users:(("ntpd",pid=1479,fd=26))
udp   UNCONN 0      0      [fe80::5200:ff:fe01:1]%eth1:123            [::]:*     users:(("ntpd",pid=1479,fd=25))
udp   UNCONN 0      0      [fe80::5200:ff:fe01:0]%eth0:123            [::]:*     users:(("ntpd",pid=1479,fd=24))
tcp   LISTEN 0      1           *     users:(("dhcpd",pid=3074,fd=10))
vyos@vyos:~$ ps aux | grep 3074
dhcpd     3074  0.0  1.8  13112  9120 ?        Ss   16:23   0:00 /usr/sbin/dhcpd -4 -q -user dhcpd -group vyattacfg -pf /run/dhcp-server/dhcpd.pid -cf /run/dhcp-server/dhcpd.conf -lf /config/dhcpd.leass
vyos      4150  0.0  0.1   6072   892 ttyS0    S+   16:39   0:00 grep 3074


I’ve created a task regarding this behavior :


if you want add anything else, you are free to add any comment.


1 Like