This still doesn't quite fix what I need, however it is close.

One machine has 4 ethernets, some of which go to other machines, one
goes to the router box.  I'd prefer that the address of a given
machine be consistent across any of those interfaces.

Ted Lemon <mellon@hoffman.vix.com> writes:

> Set the broadcast address to the local network's broadcast address.
> 
> piccola# ifconfig cs0 10.0.100.2 netmask 255.255.255.255 broadcast 10.0.0.255
> piccola# ifconfig cs0 alias 10.0.0.4 netmask 255.255.255.0
> piccola# ping 10.0.0.255
> PING 10.0.0.255 (10.0.0.255): 56 data bytes
> 64 bytes from 10.0.100.2: icmp_seq=0 ttl=255 time=1.348 ms
> 64 bytes from 10.0.0.5: icmp_seq=0 DUP! ttl=255 time=3.483 ms
> 64 bytes from 10.0.0.2: icmp_seq=0 DUP! ttl=255 time=4.020 ms
> 64 bytes from 10.0.100.2: icmp_seq=1 ttl=255 time=1.202 ms
> 64 bytes from 10.0.0.5: icmp_seq=1 DUP! ttl=255 time=1.809 ms
> 64 bytes from 10.0.0.2: icmp_seq=1 DUP! ttl=255 time=2.330 ms
> 
> piccola# netstat -rn
> Routing tables
> 
> Internet:
> Destination        Gateway            Flags     Refs     Use    Mtu  Interface
> default            10.0.0.2           UGS         0        0      -  cs0
> 10/24              link#1             UC          0        0      -  cs0
> 10.0.0.2           00:10:4b:ec:93:61  UHL         1        0      -  cs0
> 10.0.0.4           127.0.0.1          UGHS        0        2      -  lo0
> 10.0.0.5           00:a0:24:ab:fb:9c  UHL         0        0      -  cs0
> 10.0.0.255         link#1             UHL         0        2      -  cs0
> 10.0.100.2/32      link#1             UC          0        0      -  cs0
> 127.0.0.1          127.0.0.1          UH          2       32      -  lo0
> 
> Proxy arp shouldn't be required - you should have a route to each
> network for which there's an alias.   This worked fine for me just now
> when I tested it.
> 
> 			       _MelloN_