title: SSH date: 2021-01-27 11:48:05 background: bg-blue-400 tags: - protocol - remote - network - 22 categories: - Linux Command intro: |

This quick reference cheat sheet provides various for using SSH.

Getting Started

Connecting

Connect to a server (default port 22) ```shell script $ ssh root@192.168.1.5

Connect on a specific port
```shell script
$ ssh root@192.168.1.5 -p 6222

Connect via pem file (0400 permissions) ```shell script $ ssh -i /path/file.pem root@192.168.1.5

See: [SSH Permissions](/chmod#ssh-permissions)

### Executing
Executes remote command
```shell script
$ ssh root@192.168.1.5 'ls -l'

Invoke a local script ```shell script $ ssh root@192.168.1.5 bash < script.sh

Compresses and downloads from a server
```shell script {.wrap}
$ ssh root@192.168.1.5 "tar cvzf - ~/source" > output.tgz

SCP {.row-span-2}

Copies from remote to local ```shell script $ scp user@server:/dir/file.ext dest/

Copies between two servers
```shell script
$ scp user@server:/file user@server:/dir

Copies from local to remote ```shell script $ scp dest/file.ext user@server:/dir

Copies a whole folder
```shell script
$ scp -r user@server:/dir dest/

Copies all files from a folder ```shell script $ scp user@server:/dir/* dest/

Copies from a server folder to the current folder
```shell script
$ scp user@server:/dir/* .

Config location

File Path Description
/etc/ssh/ssh_config System-wide config
~/.ssh/config User-specific config
~/.ssh/id_{type} Private key
~/.ssh/id_{type}.pub Public key
~/.ssh/known_hosts Logged in host
~/.ssh/authorized_keys Authorized login key

SCP Options

Options Description
scp -r Recursively copy entire directories
scp -C Compresses data
scp -v Prints verbose info
scp -P 8080 Uses a specific Port
scp -B Batch mode (Prevents password)
scp -p Preserves times and modes

Config sample

Host server1 
    HostName 192.168.1.5
    User root
    Port 22
    IdentityFile ~/.ssh/server1.key

Launch by alias ```shell script $ ssh server1

See: Full [Config Options](https://linux.die.net/man/5/ssh_config)



### ProxyJump

```shell script
$ ssh -J proxy_host1 remote_host2

```shell script {.wrap} $ ssh -J user@proxy_host1 user@remote_host2


Multiple jumps
```shell script {.wrap}
$ ssh -J user@proxy_host1:port1,user@proxy_host2:port2 user@remote_host3

ssh-copy-id

```shell script {.wrap} $ ssh-copy-id user@server


Copy to alias server
```shell script {.wrap}
$ ssh-copy-id server1

Copy specific key ```shell script {.wrap} $ ssh-copy-id -i ~/.ssh/id_rsa.pub user@server




SSH keygen {.cols-5}
---------------

### ssh-keygen {.col-span-2}

```shell script
$ ssh-keygen -t rsa -b 4096 -C "your@mail.com"
--- ------ -------------------------------
-t Type of key
-b The number of bits in the key
-C Provides a new comment

{.left-text}

Generate an RSA 4096 bit key with email as a comment

Generate {.col-span-2 .row-span-2}

Generate a key interactively ```shell script $ ssh-keygen


Specify filename
```shell script
$ ssh-keygen -f ~/.ssh/filename

Generate public key from private key ```shell script $ ssh-keygen -y -f private.key > public.pub


Change comment
```shell script
$ ssh-keygen -c -f ~/.ssh/id_rsa

Change private key passphrase ```shell script $ ssh-keygen -p -f ~/.ssh/id_rsa



### Key type

- rsa
- ed25519
- dsa
- ecdsa



### known_hosts {.col-span-2}

Search from known_hosts
```shell script
$ ssh-keygen -F <ip/hostname>

Remove from known_hosts 

 script
$ ssh-keygen -R <ip/hostname>

Key format

Also see