SSH (Secure SHell) is a tool that allows you to connect to a remote computer (server), either on the local network or anywhere on the internet.
The basic syntax from a terminal is:
ssh username@servername
It is also possible to use other tools such as Putty and Smartty. This will open up a connection with the server and enable you to run programs/commands there. For programs with a graphical alternative, use the -X option.
As a complement to SSH, SCP (Secure CoPy) allows the transfer of files between the local and remote computer. To copy a local file to the remote computer:
scp path/to/file username@server:path/where/to/put/file
To copy from the server to the remote computer:
scp username@server:path/to/file path/where/to/put/file
Advanced Topics
- Forwarding
- Not all computers are accessible equally. It is very common for personal computers to be unreachable from the internet, being hidden away behind the router. Similarly, work computers can be accessible only though servers. This is done to limit the potential of attacks and increase the local sharing. These limitations can be bypassed using using SSH.
- Proxy
- Not all computers have the same rights either. The most common example being university computer being allowed to download papers from scientific journals while you would have to pay the equivalent of a night out at a good restaurant to get them from home. Using a proxy, your home computer can go through a server when getting its information from the internet and "look like" a university computer. Here's to reading papers comfy at home!
- SSH-Keys
- Normally, one needs a password to be able to log in other computers using ssh. Once you have access to a remote computer, it is possible to set it up to automatically recognize you when coming from a specific computer. This can be particularly convenient for connections you establish often, or when running scripts which are unable to use passwords.
- SSH-Agent
- If you use keys with passphrases, the agent can save you a lot of typing by remembering the phrases so you only have to type them once per session.
- Offline Work
- Launching a script while logged into a remote computer and letting it complete its task even after disconnecting from it.
