Ljubomir Ljubojevic wrote: >> (1) I can open port 22 on the Billion, allowing me to ssh in from >> outside. But for some reason I cannot ping the same address from outside. > This is due to modem refuses to answer to pings. You might have option > to allow it in modem config. > > Ping (ICMP) does not use ports but it is packet of type 8. Thanks again for your response. Could CentOS be preventing me from pinging the system? > When you turn off firewall, it stops routing packets so they can not be > passed to systems behind it. > > Only option I can think of is to use shorewall as firewall and add > NAT/Masquerade and the rest of the rules to routestoped confgi file: I was using Shorewall before I went over to CentOS-6, and will probably go over to it. But I don't really need to disable the firewall on the server. I just thought I'd try it as an experiment. -- Timothy Murphy e-mail: gayleard /at/ eircom.net tel: +353-86-2336090, +353-1-2842366 s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland