I have an unusual issue, at least it seems that way to me. I recently setup a box with Fedora Core 3 and shored it all up with the firewall and whatnot, but out of the blue about 5 days into its uptime the network services, which are all configured to use non standard ports just stopped answering outside requests.

The box is not on any internal network, its just connected directly to the net. I could log on to the console, and stop/restart the services but they still would not answer any requests such as a log on attempt or anything. I could ping the box, but not connect to it. As far as I can tell every network aware server (SSH, webmin, httpd, sendmail and proftpd) just stopped answering. I got undeliverable emails back from my provider stating the message could not be delivered after several attempts (sent to a local user on the box). Also the box was able to communicate out with the net because I still recieved my daily emails from the logwatch dameon, so it had a working outgoing network connection.

The network interface was up and has its usual IP address. I checked the system logs and no one has logged into the box anytime recently. Once I rebooted the box everything was fine and has been for the last 3 days. I checked the messages log but did not see anything that would indicate the cause of this.

Is there any other log file I should check? I can make logs available if someone wants to take a look at them. I will be watching the box over the next week to see if this happens again as well. Any ideas or help is appriciated.

You say you've setup a firewall, are you using IPtables? did you write the rules yousrself? either way there might be a section that will shutdown all network services (or common ports) upon detection of an intruder etc.

just a guess