Cannot authenticate server or no matching compression

[maxammann]

I'm running the latest version of the docker container. I also downloaded the static build version 2.4.0 from Github and tried to connect from two different platforms without success:

When connecting from arch-linux:

Cannot authenticate server
Reconnecting... (Cannot authenticate server)

When connecting from Debian GNU/Linux 9.12 (stretch):

Error connecting: kex error : no match for method compression algo client->server: server [zlib@openssh.com,zlib], client [none]
Reconnecting... (Error connecting: kex error : no match for method compression algo client->server: server [zlib@openssh.com,zlib], client [none])

The server only has an RSA key available.

It seems like the server is very strict about the compression and encryption algorithm. Is there a way to configure this without rebuilding the server?

[phil-blain]

Regarding compression, @nviennot indicated in another issue a few years ago that the tmate ssh server forces the use of compression. If the client does not support compression, the connection will fail. This is the case for example with the builtin version of OpenSSH on Windows:

PS C:\Users\me> ssh ***********************@nyc1.tmate.io
Unable to negotiate with 134.209.128.51 port 22: no matching compression method found. Their offer: zlib@openssh.com,zlib
PS C:\Users\me> ssh -V
OpenSSH_for_Windows_7.7p1, LibreSSL 2.6.5

[ejohb]

I'm having the same problem using a PyCharm SSH-based interpreter. Is there any workaround?

[liqwang]

Regarding compression, @nviennot indicated in another issue a few years ago that the tmate ssh server forces the use of compression. If the client does not support compression, the connection will fail. This is the case for example with the builtin version of OpenSSH on Windows:

PS C:\Users\me> ssh ***********************@nyc1.tmate.io
Unable to negotiate with 134.209.128.51 port 22: no matching compression method found. Their offer: zlib@openssh.com,zlib
PS C:\Users\me> ssh -V
OpenSSH_for_Windows_7.7p1, LibreSSL 2.6.5

I have the same problem with the builtin OpenSSH on Windows 10, and I have solved it by downloading a newer version of OpenSSH
https://github.com/PowerShell/Win32-OpenSSH/releases/download/v9.5.0.0p1-Beta/OpenSSH-Win64.zip