Introduction

This is in reference to the following article:
http://www.codeproject.com/Articles/85602/PortQry-Implementation-using-TcpClient-Socket-and

It’s been a few years since I’ve looked at this and recently I had received a notification that someone had posted a response. First I would like to agree with emilio_grv’s response in that Application Programmers should be very careful about handling timeouts within the application. As with any application development, make sure you cleanup any non-used resources as soon as possible, especially with sockets, as you’ll extinguish the available source ports that can be used. In windows environments, the default is 3977.

Background

As a connection timeout is not a parameter available within the TcpClient.BeginConnect() or TcpClient.Connect() functions, an issue arises for those who have large scale processes that must be accomplished in a timely fashion.

With the use of firewalls in the network we make a compromise, trading network visibility for security. We often no longer get a response from the TCP stack at the far end or sometimes even the ICMP message back when a packet passes a firewall whether there is a problem or not. Even more frustrating, we may have no choice in the matter, as another group or organization could be managing the firewalls, and so policy change can be difficult if not impossible altogether. Continue reading →