I just read about the "ktune" option for pppd (I'm running RHL 7.2
with the latest 2.4.9-34 colonel), which SOUNDS (ahem) like it sets
the things that need to be set for me (I think). From the pppd man:
Enables pppd to alter kernel settings as appropriate. Under Linux,
pppd will enable IP forwarding (i.e. set /proc/sys/net/ipv4/ip_forward
to 1) if the proxyarp option is used, and will enable the dynamic IP
address option (i.e. set /proc/sys/net/ipv4/ip_dynaddr to 1) in demand
mode if the local address changes.
Currently, I clear "ip_forward", do my IPTABLES setup, enable
"ip_forward", then enable pppd. What the man page doesn't say is
whether or not "ip_forward" is cleared when pppd disconnects (or if it
SHOULD be cleared). I'm also not sure about the "ip_dynaddr" option,
as only 1 of the many FAQ/HOW-TO/man/books I've read even mentions it.
I'm also not sure about "proxyarp". Do I need the routing entry
added by "proxyarp" for the other machines? Doesn't "defaultroute"
take care of that? The linux box is attempting to be a DHCP, Samba,
firewall & caching-only DNS server. I'm connecting to Earthlink via
dialup modem, and getting a unique local and remote IP everytime
(according to /var/log/messages). I use the "demand" option, and pppd
correctly dials out when it needs to. A whole lot more then it needs
to actually, but I think this is a WinXP box trying to get to MSN.