On Sun, 31 Dec 1995 15:20:27 GMT David Jones (dej@achilles.net) (<m0tWOOt-00062NC@dragon.achilles.net>) wrote:
> > After adding an IP alias, my  HP Router (27289A, 240/FR) rejects arp
> > packets form the NetBSD machine with 'Invalid ARP Source: 10.0.0.33 on
> > 204.29.161.41' and subsequently refuses to talk to it. 
> > 
> Related to that, does the HP router have a "security" setting that
> causes it to reject the "extraneous" IP addresses, in the belief that
> your dual-home machine is spoofing somebody?
> 

That was the answer.  The HP router can control the handling of ARP 
packets for  IP addresses which are not in the 'local' network. The
default is 'drop & log'. I changed that to 'accept' and all is well.

Thanks to all who responded.