> 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. 
> 
> When I then add the alias with 'ifconfig ed2 alias 10.0.0.33'
> and 'route add 10.0.0.33 localhost', the HP router starts complaining
> with the above error msg and after the original arp table entry 
> expires, it refuses to talk.

As others have said, the HP box is out to lunch.

A question for HP: how are you supposed to implement proxy ARP on a
terminal server if this HP router is the next hop?

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?