Re: dhcrelay with multiple interfaces

Thanks very much, it works by creating symlinks for each vlan interface and start a dhcrelay instance for each one.

On 3/18/26 1:30 PM, Kapetanakis Giannis <bilias@edu.physics.uoc.gr> wrote:
>
> On 18/03/2026 03:32, David Gwynne wrote:
> > On Tue, Mar 17, 2026 at 08:32:25PM +0100, Kisp??l Zsolt wrote:
> >> Hello,
> >>
> >> I try to configure OpenBSD 7.8 to act as DHCP relay with multiple
> >> interfaces.
> >>
> >> I have the following setup: one Internet facing gateway as well as DHCP
> >> server (hostname: apu4d4) and an internal router (hostname:alix2c3)
> >>
> >> ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? vlan4_192 168.4.254/24
> >> ??/
> >> ?? ?? ?? ?? ?? ?? ?? +-----------+ ??+------------------+/
> >> ?? ?? ?? ?? ?? ?? ?? |?? ?? ?? ?? ?? ??|?? ??192.168.1.0/24?? | |
> >> INTERNET------+?? APU4D4?? ??+-------------------+vr1?? ALIX2C3
> >> ??vr0+----vlan5_192.168.5.126/25
> >> ?? ?? ?? ?? ?? ?? ?? |GW&DHCPsrv |.254?? ?? ?? ?? ?? ?? ??.1| Internal router?? |
> >> ?? ?? ?? ?? ?? ?? ?? +-----------+ ??+------------------+\
> >> ??\
> >> ?? vlan6_192.168.5.254/25
> >>
> >> Config looks like this:
> >>
> >> alix2c3$ cat /etc/hostname.vr1
> >> media autoselect
> >> -inet6
> >> inet 192.168.1.1 255.255.255.0 192.168.1.255
> >> description ===VLAN_1===
> >> !route -n add -nostatic -priority 2 default 192.168.1.254
> >> up
> >>
> >> alix2c3$ cat /etc/hostname.vr0
> >> media autoselect
> >> -inet6
> >> -inet
> >> description ===Virtualization_VLANs===
> >> up
> >>
> >> alix2c3$ cat /etc/hostname.vlan4
> >> inet 192.168.4.254 255.255.255.0 192.168.4.255 parent vr0 vnetid 4
> >> description ===Interface_VLAN4===
> >> up
> >>
> >> alix2c3$ cat /etc/hostname.vlan5
> >> inet 192.168.5.126 255.255.255.128 192.168.5.127 parent vr0 vnetid 5
> >> description ===Interface_VLAN5===
> >> up
> >>
> >> alix2c3$ cat /etc/hostname.vlan6
> >> inet 192.168.5.254 255.255.255.128 192.168.5.255 parent vr0 vnetid 6
> >> description ===Interface_VLAN6===
> >> up
> >> alix2c3$
> >>
> >> I would like to use alix2c3 as DHCP relay for the subnets on vlan4, vlan5
> >> and vlan6. I found forum posts where more interfaces was provided to
> >> dhcrelay but I still get an error message:
> >>
> >> alix2c3$ doas dhcrelay -d -i vlan4 -i vlan5 -i vlan6 192.168.1.254
> >> usage: dhcrelay [-dor] [-C circuit-id] [-R remote-id] -i interface
> >> ?? ?? ?? ?? destination ...
> >>
> >> Same if I give the interface name instead of the destination DHCP server IP
> >>
> >> alix2c3$ doas dhcrelay -d -i vlan4 -i vlan5 -i vlan6 vr1
> >> usage: dhcrelay [-dor] [-C circuit-id] [-R remote-id] -i interface
> >> ?? ?? ?? ?? destination ...
> >> alix2c3$
> >>
> >> If I give only one interface as then there is no issue.
> >>
> >> What do I do wrong? Does OpenBSD dhcrelay support multiple interfaces at
> >> all?
> > no, you have a run a dhcrelay per interface.
> >
> > cheers,
> > dlg
>
> This.
>
> I make symbolic links in /etc/rc.d/
> and run something like that for multiple vlans (with carp)
>
> dhcrelay94@ -> /etc/rc.d/dhcrelay
>
> rc.conf.local:
> dhcrelay94_flags=-i carp94 xx.xx.xx.xx yy.yy.yy.yy
> pkg_scripts=..... dhcrelay93 dhcrelay94
>
> G
>
>