ssh

I am sitting at home and want to use the GUI of my Linux at work. But my work computer which is running the VNC server (mcblpc2.hi.helsinki.fi) is behind the University firewall. The only connection I can get into the firewall is via one of the university mainframes, e.g. vesuri.helsinki.fi. In order to connect using VNC, I need just two commands:

ssh -L 5901:mcblpc2.hi.helsinki.fi:5901 mjeltsch@vesuri.helsinki.fi
vncviewer localhost:1

When reinstalling an ssh server, one should keep the ssh key files from the old system. Otherwise ssh clients will receive messages of like "IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!". If you didn't keep the files, the clients can of course delete the entries from the host key file (usually /home/user/.ssh/known_hosts). When the user connects after that again to the server, the new, changed host key files are added to the host key file.

I wanted to copy a whole encrypted partition over the network into a file. You can execute many commands via ssh, but occasionally there are problems to direct the output where you want it. E.g. the "more" command doesn't output to standard out when used via ssh. You need to use "less" to get the file content displayed locally (at least using a RedHat 8 remote machine). With dd you cannot use the "dd if=input of=output" syntax but you need the "dd < input > output" syntax.