SSH Cheatsheet

ssh.sh

Base Usage
ssh [user]@[host]

Use Specific Key
ssh -i ~/.ssh/id_rsa [user]@[host]

Use Alternative Port
ssh -i ~/.ssh/id_rsa -p [port] [user]@[host]

Dynamic SOCKS Proxy
This can be used with proxychains to forward client traffic through the remote server.

ssh -D8080 [user]@[host]

Local Port Forwarding
This will bind to [bindaddr]:[port] on the client and forward through the SSH server to the [dsthost]:[dstport]

ssh -L [bindaddr]:[port]:[dsthost]:[dstport] [user]@[host]

Remote Port Forwarding
This will bind to [bindaddr]:[port] on the remote server and tunnel traffic through the ssh client side to [localhost]:[localport]

ssh -R [bindaddr]:[port]:[localhost]:[localport] [user]@[host]

Establish VPN over SSH
The following options must be enabled on the server side.

PermitRootLogin yes
PermitTunnel yes
ssh [user]@[host] -w any:any

You can see the established tun interface by typing ifconfig -a

The interfaces and forwarding must still be configured. This assumes that we are going to forward 10.0.0.0/24 through the remote server. We are also assuming that the server’s main connection is through eth0, and both client/server stood up tun0. This may be different if you already have existing VPN connections.

Client

ip addr add 192.168.5.2/32 peer 192.168.5.1 dev tun0
# Once Server is setup, run the following to add routes
route add -net 10.0.0.0/24 gw 192.168.5.1
Server

ip addr add 192.168.5.1/32 peer 192.168.5.2 dev tun0
sysctl -w net.ipv4.ip_forward=1
iptables -t nat -A POSTROUTING -s 192.168.5.1 -o eth0 -j MASQUERADE
Execute a One Liner
ssh -i ~/.ssh/id_rsa [user]@[host] "sudo apt-get update && sudo apt-get upgrade"

Files
File	Description
~/.ssh/	Directory for user-specific SSH configuration
~/.ssh/authorized_keys	Lists public keys authorized for logging into this user
~/.ssh/config	Per-user config file. Can specify how to connect, with which keys etc
~/.ssh/id_*	Key files, both public and private
~/.ssh/known_hosts	Contains list of public host keys known to user
/etc/ssh/ssh_config	Global SSH client configuration
/etc/ssh/sshd_config	SSH server configuration
Generating Keys
ssh-keygen

Adding Authorized Keys
cat id_rsa.pub >> ~/.ssh/authorized_keys

The following will remotely copy your public key to authorized_keys on [host]

ssh-copy-id -i ~/.ssh/id_rsa [user]@[host]

SSH Escape Sequences
Simply type the following combinations to escape SSH sessions.

Escape Sequence	Description
~?	List all options
~B	Send BREAK to remote host
~R	Request Re-key
~V/v	Decrease / Increase verbosity
~^Z	Suspend SSH
~#	List forwarded connections
~&	background ssh
~~	Send the escape character instead of escaping the next char
SCP
SSH Copy utility for pushing and pulling files remotely

Copy from remote to local
Copy remote file.txt to /tmp/file.txt

scp [user]@[host]:file.txt /tmp/file.txt

Copy from local to remote
Copy local file.txt to remote /tmp/file.txt

scp file.txt [user]@[host]:/tmp/file.txt

Copy recursively (full directories)
The following will copy remote /home/ubuntu/.vim directory and all of its contents to ./vim.

scp -r [user]@[host]:/home/ubuntu/.vim ./vim

Use non-standard port
Uses -P instead of -p switch in regular SSH command. The following uses port 2222.

scp -P 2222 [user]@[host]:/home/ubuntu/test.py ./test.py