Actually, I thought he was looking for help in understanding how a firewall works with a dialup link. He sounds like he's read a bit already about how to configure iptables for filtering and masquerading.
Bill, linux will work just fine with a standard serial modem. When a ppp connection is established, the interface pppN (probably ppp0 in your case -- presuming you don't have more than one ppp link, eg, adsl or isdn) is brought up. You can apply rules to this interface just the same as you can any other interface. I believe Rusty's NAT HOWTO on the Netfilter (iptables) site (netfilter.samba.org) has a little on this. An example rule (in iptables) might look like this: # iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o ppp0 -j MASQUERADE This rule would masquerade connections from an internal class C (192.168.0.0 - 192.168.0.255) going out over interface ppp0. If I recall correctly, iptables will just ignore this rule if ppp0 doesn't exist at a given moment. So all you need to do to setup a gateway with a serial modem is get the modem dialling out and establishing an internet connection (ppp session) in the way that you want (Do you want it dial-on-demand, a permanent connection, etc) -- there are numerous tools to do this, not just the infamous pppd -- and then apply some ipchains or iptables rules to masquerade, and/or firewall. HTH, Matt. At 11:04 22/01/2002, Jeff Waugh wrote: ><quote who="Stephan Borg"> > > > Yes, RH7.1 uses IPChains. I've used this setup before I got onto ADSL - > > works a treat. > > > > Let me know off the list if you get stuck. > >Bill's looking for a utility to handle it for him - doesn't Red Hat have a >firewall/masquerading tool (that is not at the system administrator's level >ala ipchains/iptables)? > >- Jeff > >-- > "To do: Start up a a magazine dedicated to picky grammar. Call it 'Whom > Weekly'." - WzDD >-- >SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ >More Info: http://lists.slug.org.au/listinfo/slug -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://lists.slug.org.au/listinfo/slug
