SSH

From Luleå Academic Computer Society

SSH is one of the most secure ways to execute commands on remote computers. It can also be used to transfer data from your computer at home to Ludd. Due to its inherent security, SSH is more preferable than FTP for transfering files to and from our servers.

Contents

Getting the program

On most Unix-like systems (Linux, *BSD, Mac OS X) the most popular SSH suite, OpenSSH, is usually installed by default. In order to log in to Ludds server, use one of the following:

ssh [user]@[computer-name].ludd.ltu.se
ssh -l [user] [computer-name].ludd.ltu.se

where [user] is your LUDD username and [computer-name] is one of the names from the Computer List.

For Windows, we recommend PuTTY

After logging in, you will be presented with your shell of choice.

Transfering files via SSH

In order to copy files from one computer to Ludd there are two methods available: scp (secure copy) or sftp (ftp "emulated" through ssh).

Via scp:

Commandline:

scp /path_to/some_file [user]@[computer-name].ludd.ltu.se:/path_on/remote_machine

If you prefer a Windows GUI alternative, WinSCP might be for you.

Via sftp:

Commandline:

sftp [user]@[computer-name].ludd.ltu.se

Note: SFTP is not to be confused with FTPS, FTP with SSL

If you prefer a Windows GUI alternative, Filezilla might be for you.

Tunneling connections

SSH can be used to encrypt most other TCP/IP connections. For example, this can be used to encrypt and access the SMTP server from outside the Campus network.

Start by setting up a tunnel from your machine to mailhost.ludd.ltu.se:

ssh -L 1025:mailhost.ludd.ltu.se:25 mailhost.ludd.ltu.se

This will start a shell on the remote machine as usual, but it will also forward all connections to 1025 on your local machine to our mailhost. Use your mail client to set up your local machine as a SMTP server as usual, with the exception of the changed port (1025, as oppossed to the usual 25). When you're done sending your mail, return to your shell and close the connection as usual.

SSH in your browser

If are unable to install applications and can run Java applets you can use the SSH Java applet.

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