Question

Why sshd won't talk on port 1723 but will on any other?

Ni!

I’ve correctly configured sshd to listen on port 1723, that is:

  1. I have no other process listening on port 1723 (according to netstat)
  2. 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:

Client side:

$ ssh -vvv
Connection established.
...
ssh_exchange_identification: read: Connection reset by peer

Server side:

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]

Thanks!

Show comments

Submit an answer

This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

Sign In or Sign Up to Answer

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Want to learn more? Join the DigitalOcean Community!

Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in Q&A, subscribe to topics of interest, and get courses and tools that will help you grow as a developer and scale your project or business.

Hi @xMudrii , thanks, I had tried under two different and quite distinct networks - one wifi another cellphone - and got the same result, so I assumed it was not a network problem, but since you’ve mentioned it again I’ve now I’ve tried under a third network and it does work. So it is indeed the client networks blocking, not an issue with my server at all. Thanks.