If I set any service to listen on port 80, nothing can connect to it except from itself.
1. IPtables is stopped and SELinux is disabled.
2. "lsof -w -n -i tcp:80" confirms the port is listening
3. Can telnet to 127.0.0.1 and private IP 10.0.0.1 on port 80 only from the host itself
4. Cannot telnet to private IP 10.0.0.1 from any other LAN machine or indeed from the public IP which is mapped to the server's private IP.
5. If I switch apache to listen on any other port, say 8888, it works fine from both LAN and WAN inbound connections. Also, all other normal services are working from external connection on their standard ports, SSH 22, FTP 20/21, MYSQL 3306, even HTTPS 443 works. Just anything on port 80 fails to connect.
6. If I modify the config files for SSH or FTP to listen on port 80, the same behaviour is observed - can only connect from the host. Setting them to an other port such as 8888 works as expected externally.
7. Rootkit Hunter plus OSSec Rootcheck report all clean.
8. This server has been running 24/7 for 1.5 years and working fine up until a few days ago..
Any suggestions as to what on earth is blocking the port? Corrupt network software?
I'm about to embark on upgrading Fedora 8 to 9, 10, 11, 12 then 13 as I've tried everything else.
Thank you from Mr. Baffled