I recently setup a new SUSE box for the purposes of acting as an ftp/sftp server. It’s currently setup to run ProFTPD 1.3.3.rc3 and mod_sftp/0.9.7.
The server has two internal network interfaces eth0 and eth1. eth0 is purely for internal use to accept ftp and ssh. eth1 is outward facing and receives connections from the WAN via SFTP over port 22.
The problem I am facing is that after half hour to an hour eth1 stops accepting connections whenever there is no SSH connection present on eth0. I can’t figure out why this is happening.
ProFTPD is setup as follows:
SocketBindTight directive is on, default server and port are commented out.
When the external interface is unreachable the proftpd and proftpd-sftp logs show no record of any connection attempt. I have noticed however if I leave eth0 down eth1 stays contactable without problem. Can anyone give me some pointers on what I can check to find out why this may be happening.
If you have sshd running have you disabled ssh or moved the port somewhere else for eth1? Because both attempt to listen on port 22 if neither is modified.