.NET FTP Client
.NET FTP Client library written in C#

.NET Telnet
.NET Telnet is a telnet library written for the MS .NET Framework. It is inspired by the Java Telnet Application. .NET Telnet is Free Software, released under the GPL.

edtFTPnet
edtFTPnet is the first choice of .NET developers worldwide for incorporating FTP functionality into their applications. edtFTPnet is Open Source, licensed under the LGPL, the GNU Lesser General Public License. This means you can freely embed edtFTPnet into your commercial .NET applications.

Granados
Granados is an SSH client library for .NET. It has the following features: Both SSH1 and SSH2 are supported; Granados implements AES, Blowfish, and TripleDES algorithms for encryption; RSA and DSA for server authentication algorithms; Key generation and user authentication using RSA or DSA are also supported; TCP port forwarding is available.

IceChat
IceChat is an Internet Relay Chat Client designed to connect to multiple IRC Servers. You can connect IceChat to an unlimited number of servers, all in one session (No need to start multiple copies of IceChat).

lphant
Open source GUI for the lphant .NET eDonkey p2p kernel library.

Metro Packet Library
This project is a library written in C# which provides a rich set of classes for working with IP version 4, TCP, UDP and ICMP with ease of use. Useful for writing packet sniffers, network anaysis tools or utilities such as trace route or ping for example.

OpenSmtp.net
OpenSmtp.net is an open source SMTP component written in C#. It does not rely on the .Net Framework System.Web.Mail classes and allows developers to use SMTP servers other than MS SMTP. It also has a web service that allows the sending of email via HTTP.

SmartIrc4net
SmartIrc4net is a multi-threaded and thread-safe IRC library written in C#. It allows you to communicate with IRC servers. The API features full channel syncing and is splitted in 3 layers: IrcConnection, IrcCommands and IrcClient.

VNC-Client for .NET
VNC-Client for .NET is a VNC-Client written in C# using the .NET Framework.