Defense and Network Security

Est. read time: 1 minute | Last updated: July 06, 2025 by John Gentile

Contents

Networking
- Routing
- SSH
  - SSH Tunneling
- Tools
System Hardware Security
- Disk Encryption
References

Networking

Routing

Manually map an alias/hostname to an IP address by adding to /etc/hosts file, like:
```
192.168.56.4    mylinuxbox
```

SSH

Use Key-based auth for SSH to aid in passwordless SSH login/commands- usually as simple as $ ssh-copy-id <user>@<hostname/IP>.
- How to Configure SSH Key-based authentication on a Linux Server
How to Protect SSH with fail2ban on Ubuntu 22.04
- Configure Fail2Ban for permanent and persistent bans

SSH Tunneling

SSH Tunneling can be used to forward certain ports or services over a secure SSH connection. It’s also useful if a local system wants to expose non-SSH services but only has an SSH port open externally through a router. For example, to tunnel Remote Desktop (RDP) to a remote server <remote>:

$ ssh -L 8888:localhost:3389 <username>@<remote>

You can then connect to the RDP session with localhost:8888.

Also you can forward multiple ports in one connection, for example:

$ ssh -L 8888:localhost:8888 -L 8889:localhost:8889 <username>@<remote>

Tools

Wireshark: prolific network protocol analyzer, packet capture and traffic visualization tool.

System Hardware Security

Disk Encryption

Create a LUKS encryption layer on a selected disk (erasing everything on disk!) with $ sudo cryptsetup luksFormat /dev/sdb.
Open encrypted drive with $ sudo cryptsetup luksOpen /dev/sdb encrypted_drive.
- If the disk hasn’t been formatted yet, do $ sudo mkfs.ext4 /dev/mapper/encrypted_drive.
Mount the resultant unlocked drive with $ sudo mount /dev/mapper/encrypted_drive /media/encrypted_drive.
- You might need to change permissions on the mount folder to your user with $ sudo chown -R username:group directory.