The Dynamic Host Configuration Protocol or just DHCP provides networked devices with all the necessary parameters, IP addresses, network masks, the gateway or DNS servers IP addresses, so that they can actively participate in the network and start exchanging data with other devices or workstations. This automated operation, which greatly relieves the system administrator from [...]

This is an excellent article that describes in detail how P2P applications can bypass the firewall and accept incoming data without opening any ports in the firewall configuration. This trick is used by the majority of VoIP software. In this article, the author not only describes how the popular internet telephony software Skype manages to [...]

In some of my older articles, at least where an SSH tunnel is involved, I keep mentioning a specific way of initializing such an encrypted tunnel, which results in the automatic closure of the tunnel after the job on the remote server is finished. Since this is my method of choice, I decided to provide [...]

One of the Linux command line tools I had initially under-estimated is netcat or just nc. By default, netcat creates a TCP socket either in listening mode (server socket) or a socket that is used in order to connect to a server (client mode). Actually, netcat does not care whether the socket is meant to [...]

These are the articles that got me into network programming in Python: Socket Programming HOWTO by Gordon McMillan. Sockets programming in Python by M. Tim Jones.

Actually, this title is not very descriptive, as sharing music with Rhythmbox takes only one click of the mouse. However, this article intends to provide an overview of what happens behind the scenes after this mouse button has been pressed and how Rhythmbox and Avahi work together in order to make the sharing of music such an easy task.

This is a dictionary protocol server implementation written in Python. I decided to write this stuff just to learn Python. The goal is to create a full-featured dictionary server, while making the retrieval of word definitions from any source and in any language easy. The server is usable and acts as a proper UNIX daemon.

This article describes in brief how to configure VNC server instances for one or multiple users on a remote machine, how to use VNC to start graphical applications on boot and finally how to enhance security by connecting to the server through encrypted SSH tunnels.

In this article I describe how to configure the SSH server, so that users authenticate using keys, how to generate DSA keys using ssh-keygen, how to configure ssh-agent and finally how to use ssh-add to manage cached passphrases.

Can a network card have multiple IPs assigned to it? The answer is absolutely yes! Some times, for example when you run several servers on a machine or when you need IP-based Apache virtualhosts, it is useful to bind a server or a virtualhost on its own IP address. I am not going to get [...]