[Dnsmasq-discuss] failed to bind DHCP server socket: Address already in use

Michael Rack dnsmasq.list at michaelrack.de
Tue Oct 14 10:23:17 BST 2008

I use dhcp-fwd v0.7 patched by my self to support dhcp-server override 
and many other features.

But it is realy suspect that dhcp-fwd creates two identical entrys:

udp        0      0    *
udp        0      0    *
udp   108324      0    *
udp        0      0    *

And DNSMASQ creates only one of each port (67/68) ?!? I will try to 
implement the SO_REUSEADDDR option to the dhcp-fwd process and hope to 
get it running :-) My C++ skills are very terrible *smile* But i think i 
will do it :-)


Simon Kelley schrieb:
> Which dhcp-forwarder are you using?
> There's no portable way to listen on an _interface_ in Unix, one 
> normally listens on the _address_ of an interface, but that breaks 
> DHCP which has to receive packets sent to/from strange addresses 
> during the configuration process. For that reason, a DHCP server has 
> to listen on the wildcard address,
> Dnsmasq partly solves this problem by setting the SO_REUSEADDR flag on 
> DHCP sockets when --bind-interfaces is set. That allows the wildcard 
> address to be bound multiple times, as long as every instance sets the 
> flag. That allows multiple instances of dnsmasq to run, but it breaks 
> when something else is binding the wildcard address and NOT setting 
> SO_REUSEADDDR. I suspect that's the case here.
> Cheers,
> Simon.

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