SSH

Just as an internal note, if you get the following error trying to pull or push to a git repo: "Agent admitted failure to sign using the key" Your issue might be due to simply not having an identity defined in SSH. Simply use the "ssh-add" command to fix it.

A very useful resource (in French) to use SSH, with specific use cases: Les_tunnels_SSH Another useful (and short one for tunneling): http://www.howtoforge.com/reverse-ssh-tunneling

Connecting to another remote computer through a common central computer

In short, if you have a configuration with 3 computers (A - B - C) and you want to connect to A (arrival) from C (client) but A doesn't allow direct SSH connection, you can do the following:

1. On A and B, install openssh-server
2. On A,

On Linux systems, there used to be a mildly complicated but tedious way to allow you to SSH another computer using your public key, which involved finding and copying your public key on the other host, then connecting to the host and putting this key into ~/.ssh/authorized_keys. Now there is a much simpler way to do that... Just launch the following command (with your own data), enter your password, and that's it!

ssh-copy-id  yourusername@remote.host.address

I love administrative simplification!

A lot of people use the root account to do anything they need, just because it is easier… This is a really bad idea, as that user can do anything to the system.

SSH (the Secure SHell) is a secure replacement for many UNIX tools like telnet, ftp, rsh, rcp, rlogin, rexec, and many more, which have proven to be insecure, even if most UNIX systems still use them by default, and even Microsoft has now begun to integrate those into his operating systems. I'll talk about the most used one, and free OpenSSH, which has been created by the OpenBSD team.

This article was first written in October 2007 for the BeezNest 
technical website (http://glasnost.beeznest.org/articles/364).

On most GNU/Linux distributions, bash is able to read hostnames in  /.ssh/known_hosts to autocomplete ssh commands. For security reasons though, hostnames are no longer stored in clear text in those files on most distributions, defeating this feature of bash's autocompletion. To tell SSH (client) to not obfuscate hostname, just set the HashKnownHosts option to no in /etc/ssh/ssh_config.