FreeRADIUS sends proxy packets out the proper interface, but with the wrong source IP (simple udpfromto problem?)

Alan DeKok aland at
Wed Oct 19 08:02:09 CEST 2011

Adam Bultman wrote:
> Problem: The detail reader, when sending the accounting packets, sends
> them out the *correct* interface, but with the *wrong* source IP
> address. (It will send out eth2, but have the source IP of eth0.)

  You're running Linux, right?  And both interfaces are on the same network?

  It's a Linux bug.  The Linux people think it isn't a bug, so it hasn't
been fixed for 10+ years.

  As a hint, FreeRADIUS uses the standard socket calls to send/recv
packets.  There's no magic "send packets out the wrong interface" code
in it.  All of the routing is handled by the kernel.  So... blame the
kernel for routng problems.

>  I
> proxy to other hosts as well, so I cannot simply force a single proxy ip
> address, since that will break other things. (As far as I can tell.) All
> my routing is good, no firewalls are in the way, etc.

  You can set "src_ipaddr" for each home server.  See raddb/proxy.conf.
 This is documented.

> The mailing list shows some results, but not quite what I'm looking for.
>  Is my problem a simple lack of 'udpfromto'?


  Alan DeKok.

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