I have just gotten a DSL connection for home and I bought a Linksys
router/firewall to put between the DSL modem and my machines. The box
allows selective port forwarding. What ports should I allow? I don't
really need services for machines outside my little network to use very
often since usually I can use the services at the other end. Once in a
while I might want telnet or ftp. My kids use AOL instant messenger/gaim
and sometimes play games on the internet. When there is trouble I might
need to use traceroute or some other tool. I looked through /etc/services
but not being a network guru I am having hard time deciding which ones
I need. 20 and 21 for ftp? 22 for ssh? 23 for telnet? Is there any need
for tftp? 161 snmp? 513? Behind the Linksys box the machines either
boot linux or windows 95. The win 95 machines don't run many services,
do they? What does AOL IM use? 194? What do these games use? Linksys
mentions using their DMZ for the machine playing the game but if I
understand correctly that means that the machine is outside the firewall
effectively.
I have my hosts.deny and hosts.allow set to allow only certain domains
or static addresses so I think I am not too badly exposed when the ports
are visible and linux is up.
TIA for any suggestions or pointers to documentation.
Dale Alspach
