Network port open, but no process attached?

Solution 1:

Ports open by the kernel won't show up with program name. Some NFS and OCFS stuff come to mind. Maybe it's something like that?

Or it could be a kernel bug. Check kernel logs for OOPS and BUG.

Solution 2:

Have you run netstat and lsof as root or with sudo? Notice the last column:

netstat -ln --program
tcp        0      0 192.168.21.1:53         0.0.0.0:*               LISTEN      -               
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -

sudo netstat -ln --program
tcp        0      0 192.168.21.1:53         0.0.0.0:*               LISTEN      2566/named      
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      2566/named      
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      3125/sshd

From the netstat manpage:

You will also need superuser privileges to see this information on sockets you don’t own.

How do you know there isn't one running? If the port is in use it makes sense that it would exit immediately with a 'socket in use' error. what happens when you telnet to the port?

telnet localhost 5666