# ssh

#### SSH change port

[**How to change SSH port on Centos 6, 7, and 8.**\
\&#xNAN;*Changing SSH Port will help to secure your Linux VPS server, here is ultimate guide how to secure linux vps server …*monovm.com](https://monovm.com/blog/how-to-change-ssh-port-on-centos/)

**Add to sshd configuration**

Go to the file

```
# nano /etc/ssh/sshd_config
```

and add line

```
Port <SSH_NEW_PORT>
```

**Configure SELinux**

```
# semanage port -a -t ssh_port_t -p tcp 50
```

**Configure Firewall**

```
# firewall-cmd --permanent --remove-service=ssh
success
# firewall-cmd --permanent --add-port=<SSH_NEW_PORT>/tcp
success
# firewall-cmd --reload
```

Restart sshd service

```
# systemctl restart sshd 
# systemctl status sshd.service
```

Remote access be like

```
# ssh -p <SSH_NEW_PORT> server@ip
```

#### SSH using keys

On your remote device follow these steps.

**Generate key**

[Comparison](https://gravitational.com/blog/comparing-ssh-keys/): TL;DR, use RSA 4096 or ed25519.

```
$ ssh-keygen -t ed25519
```

By default, will be stored at /home/user/.ssh/id\_ed25519

Generate a passphrase with [KeePassXC](https://keepassxc.org/) and use it as passphrase when it asks you for one.

**Add it to remote key (server)**

```
$ ssh-copy-id -p <PORT> -i ~/.ssh/id_ed25519 user@remote
```

This will add the public key (i.e. id\_ed25519.pub) to the the server file \~./.ssh/authorized\_keys

**Add passphrase to KeePassXC**

Follow this [tutorial,](https://www.techrepublic.com/article/how-to-integrate-ssh-key-authentication-into-keepassxc/) so you can add the passphrase for the generated key automatically to the ssh-agent whenever KeePassXC db is unlocked.

Now, passphrase won’t be asked when KeePassXC is unlocked.

**Disable ssh with password**

<https://linuxhandbook.com/ssh-disable-password-authentication/>\
Open file /etc/ssh/sshd\_config and set

```
PasswordAuthentication no
```

Next, restart ssh service

RHEL:

```
$ sudo service ssh restart
```

Arch:

a


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