Regarding dhcp server behavior

[Simon Hobson]

Shweta Jogi <Shweta.Jogi at Sophos.com> wrote:

> Command to start Relay : 
> sudo dhcrelay -d -i enp0s3 -i enp0s8 30.30.30.30
>  
> So my server is running on enp0s8, but I am not able to see any packets coming to DHCP Server.

Can't see packets according to dhcpd logs, or can't see packets when using a packet sniffing tool (eg tcpdump or wireshark) ?

By default, the dhcp server uses raw packets because it needs to handle broadcast traffic from clients on local networks. For this reason, packet handling is a bit different from most network connected programs - and I suspect it's just ignoring packets sent to 30.30.30.30 or just not seeing them at all. You can change this by turning off a setting (something related to "use raw packets") and recompiling - then the server will just use the normal IP stack (but won't be able to handle local, ie not relayed, clients).

I suspect that in your case, you just need to change your relay invocation to send packets to 20.20.20.22 - the dhcp server will be listening on this interface and will see the packet.