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I usually connect to a remote machine through a firewall with:

ssh -xv [email protected]

And then:

ssh -xv [email protected]

Notice that remote is actually an IP address. I've seen this question and tried to write my ~/.ssh/config file as:

Host ras            
Hostname ras.cse.ust.hk
User farshidhss         

Host farshid
ProxyCommand ssh -q ras nc -q0 10.89.100.72 22

And then tried ssh -xv luca@farshid, but it stucks at the last line of:

luca@jarvis:~$ ssh -xv luca@farshid
OpenSSH_7.2p2 Ubuntu-4ubuntu2.1, OpenSSL 1.0.2g  1 Mar 2016
debug1: Reading configuration data /home/luca/.ssh/config
debug1: /home/luca/.ssh/config line 5: Applying options for farshid
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Executing proxy command: exec ssh -q ras nc -q0 10.89.100.72 22
debug1: permanently_drop_suid: 1000
debug1: identity file /home/luca/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/luca/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1

I checked that the ports are correct and tried also ProxyCommand ssh -W 10.89.100.72:22 farshid but without success and netcat is installed on ras.cse.ust.hk (which nc returned /bin/nc).

Updated ~/ssh/config:

Host ras            
Hostname ras.cse.ust.hk
User farshidhss         

Host farshid
User luca

ProxyCommand ssh -o 'ForwardAgent yes' [email protected] 'ssh-add && nc %h %p'

Tried to connect with ssh -xv farshid but having same output of before and stucked there

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user6321
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  • Try `ProxyCommand ssh -o 'ForwardAgent yes' ras 'ssh-add && nc %h %p'` and set `User luca` under your entry for `Host farshid`. Also on the remote system, the messages form sshd in the logfiles might prove useful. Client-side ssh doesn't give much info on why a connection failed. – con-f-use Mar 26 '17 at 14:23
  • @con-f-use thanks for your answer, please give a look at my updated question – user6321 Mar 26 '17 at 14:31
  • Not quiet what I meant. So, your [~/.ssh/config](http://paste.ubuntu.com/24254024/) should be like in the link and then connect with `ssh farshid`. – con-f-use Mar 26 '17 at 14:46
  • @con-f-use is the updated version right now? – user6321 Mar 26 '17 at 15:03
  • No, look at my link: [~/.ssh/config](http://paste.ubuntu.com/24254024/) – con-f-use Mar 26 '17 at 15:04
  • 1) If you have new enough `ssh`, use `ssh -W 10.89.100.72:22 ras` as a proxy command. 2) Show us more debug information. Add `-vvv` to both of the `ssh` commands or use `LogLevel DEBUG3` in `ssh_config` for both of the hosts. – Jakuje Mar 26 '17 at 16:12
  • @con-f-use thanks for your help, now it works correctly. However, if I want to do both connection with `-xC` for speeding up the ssh session (taken from [here](http://serverfault.com/questions/35453/what-can-cause-slow-ssh-session) ), all I need to do is `ProxyCommand ssh -xoC ...` or what? – user6321 Mar 27 '17 at 17:05
  • @con-f-use in addition, in the question that I linked above it seems that commands like `scp` should work. Both `rsync` and `scp` seems not to work, both if sending or receiving data. – user6321 Mar 27 '17 at 17:40
  • For compression, I would add something like `Compression yes` and `CompressionLevel 5` below `Hostname ras.cse.ust.hk`. Copying with scp for instance using the command `scp farshid:~/.bashrc farshidbashrc` should work. For rsync you might need to add the appropriate ssh-key with the `-i` option. – con-f-use Mar 28 '17 at 08:52

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