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. The command I finally managed with is ssh -l root remote-machine 'dd < /dev/hda1' > hda1.bin