982Mysterious SSH Connection Problem
Step before: Trying to connect to a server with a SSH key. System: OSX, Big Sur
Connecting to a Server via SSH fails:
georg@Fischer ~ % ssh trembl@myserver -v OpenSSH_8.1p1, LibreSSL 2.7.3 debug1: Reading configuration data /Users/georg/.ssh/config debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 47: Applying options for * debug1: Connecting to myserver.com port 22. ssh: connect to host myserver.com port 22: Operation timed out
Did not work for ca. 1 hour. Same connection problem to different account with same provider, other account with same provider worked.
(Possible) Solution: Intentionally mis-spelled username, -v not stopping and timing out, log-in now possible.
nmap -Pn -p22 myserver
to check if the port is open or filtered.
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower. Starting Nmap 7.91 ( https://nmap.org ) at 2021-03-30 14:15 JST Nmap scan report for trembl@myserver (xx.xx.xxx.xxx) Host is up (0.21s latency). rDNS record for xx.xx.xxx.xxx: xx.xx.xxx.xxx PORT STATE SERVICE 22/tcp filtered ssh
It should say:
PORT STATE SERVICE 22/tcp open ssh
Creating a ssh connection to the server from another computer (on the same network) worked. Somehow, after that check, the connection on this computer also worked. Very mysterious.
Approach 2 did not work the next time. Switching to a different network (phone hotspot) worked. Maybe restarting the router?