[lug] ARP packets not seen?

David L. Anselmi anselmi at anselmi.us
Sun Jul 19 11:39:06 MDT 2009

Tkil wrote:
> I'm guessing that either I have a defective switch (Linksys 5-port
> 10/100 cheap-ass switch, so not outside the realm of possibility), or
> that something on the linux box is keeping those ARP replies from
> reaching the switch in the first place.

Swap out the port and cable (and NIC if you can) with known good ones. 
If the kernel is generating ARP replies it shouldn't be blocking them.

Check that you have no firewalling on the Linux box.

Check your selinux settings.  I don't think it has any relation to 
networking but it's also been the culprit in other stupid "everything is 
correct but it still doesn't work" problems.

> p.s. I also noticed that doing a manual configuration on the linux
>      box, and then bringing the interface down then up, made a entry
>      in the routing table for ... no idea why, and I worry
>      that it's somehow sending packets off into the weeds.

That's a zeroconf address.  MS calls it APIPA.  If you go through all 
the effort of learning the zeroconf components and configuring them 
across your network it might be a good thing.  But otherwise you want it 
turned off.  At the moment it's a toss-up whether I'll learn IPv6 or 
zeroconf first.


More information about the LUG mailing list