About SSH Cheatsheet

Keys, connect, port forwarding, ~/.ssh/config, file transfer. Part of the DevTools Surf developer suite. Browse more tools in the Cheatsheets collection.

Use Cases

• Junior devs setting up SSH keys for GitHub for the first time
• DevOps engineers configuring jump hosts and bastion access
• Backend developers creating SSH tunnels to remote databases
• Sysadmins managing multi-server SSH config files efficiently

Tips

• Copy the ~/.ssh/config template to avoid typing long commands
• Use the port forwarding section for secure database tunnels
• Check the key generation command for Ed25519 best practices

Fun Facts

• SSH was invented by Tatu Ylonen in 1995 at Helsinki University of Technology after a password-sniffing attack on the university network.
• The default SSH port 22 was chosen by Ylonen because it sat between telnet (port 23) and ftp (port 21), both of which SSH aimed to replace.
• Ed25519 keys, based on Daniel J. Bernstein's Curve25519, are 256 bits but provide security equivalent to a 3072-bit RSA key.

FAQ

Does it cover SSH keys?

Yes — generation, types (ed25519 is current best), and how ~/.ssh/authorized_keys works.

Port forwarding?

Local (-L), remote (-R), and dynamic SOCKS (-D). Common uses: accessing a DB behind a bastion, exposing a local server to collaborators.

What about ~/.ssh/config?

Essential — host aliases, ProxyJump for bastions, ControlMaster for connection reuse. Saves enormous friction once set up.

How do I transfer files?

scp is in the cheatsheet. For modern workflows, rsync (covered briefly) is often better. SFTP is mentioned for GUI clients.