Why sshd won't talk on port 1723 but will on any other?
I've correctly configured sshd to listen on port 1723, that is:
- I have no other process listening on port 1723 (according to netstat)
- Changing the number to any other available port works fine
Apparently, see logs below, it gets to the point that a connection (a tcp connection) is established, but doesn't get through on the ssh level.
I need it to listen on port 1723 because, on a network I use often, it is the only allowed port besides 80 and the server already listens on 80 for web connections. I have never configured a VPN (port 1723 is usually a VPN port) on this server.
Any ideas? Any chance this is a problem from DigitalOcean's side? Something within sshd?
This is what I get from the outputs/logs after the connection times out:
$ ssh -vvv Connection established. ... ssh_exchange_identification: read: Connection reset by peer
Log: sshd[xxx]: Did not receive identification string from x.x.x.x Netstat: tcp 0 39 x.x.x.x:1723 y.y.y.y:44983 ESTABLISHED 23401/sshd: [accepted]