How to configure an IRC server on a VPS?

Here’s a basic guide on how to configure an IRC server using UnrealIRCd on a Linux VPS for example:

1. Secure your system: Before installing any new services on your server, it’s always recommended to update and upgrade your system to ensure that you are using the latest and most secure versions of software.

1. Connect to your VPS: Open the terminal on your local machine and connect to your VPS server through SSH. For example: ssh username@your_server_ip

1. Install dependencies: Depending on the OS distribution, you need to install some dependencies. Here’s how to do it on Ubuntu/Debian:

```
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install build-essential libcurl4-openssl-dev zlib1g-dev libssl-dev libpcre3-dev
```

1. Download UnrealIRCd: Go to the UnrealIRCd site and find the download link for the latest version.

1. Extract the archive:

```
tar zxvf Unreal3.2.10.5.tar.gz
cd Unreal3.2.10
```

1. Run the configuration script:

```
./Config
```
Follow the instructions in the script. The defaults mostly work fine but you can customize based on your needs.

1. Compile the server:

```
make
```

1. Install the server:

```
sudo make install
```

1. Change directory to where UnrealIRCd is installed & configure it:

```
cp doc/example.conf unrealircd.conf
nano unrealircd.conf
```
Modify unrealircd.conf according to your needs – set admin information, allow blocks for clients, server password, etc.

1. Start UnrealIRCd:

```
./unreal start
```

1. Now you should be able to connect your IRC client to your own IRC server using the IP address of your VPS and the port you configured in the unrealircd.conf (default is 6667).

Just remember, running an IRC server requires vigilant administration, good security practices, and generally a commitment of time and resources. Make sure you’re aware of these responsibilities before you start.

This is a basic, non-exhaustive guide. For more detailed instructions, consult the official UnrealIRCd documentation and guides, and always refer to manuals and help specific for your VPS provider and your OS distribution.