I have what must be a fairly typical setup:  a PPP link to my ISP which has
assigned me a static IP address; a local class C network (a real allocation,
not one of the nonrouted networks) for my home Ethernet (doesn't EVERYONE
have Ethernet in their homes?).

I would like for outgoing connections to come from "my" network,
rather than from the PPP address.  I've tried adding an alias by
putting it in /etc/ifaliases, but it doesn't appear to stick;
netstat -i reports no additional addresses on the ppp interface after
it comes up.  If I add the alias after ppp is up, the alias appears,
but connections are still branded with the original ppp address.

There must be SOME way of getting the effect that I want (short of
using a dedicated router).  (What I'm trying to avoid is other systems
getting offended when my system claims to be "jfwhome.funhouse.com"
when a reverse-IP lookup proves that its name is "funhouse-gw.ultra.net".)