Artificially create a connection timeout error

Question

I've had a bug in our software that occurs when I receive a connection timeout. These errors are very rare (usually when my connection gets dropped by our internal network). How can I generate this kind of effect artificially so I can test our software?

If it matters the app is written in C++/MFC using CAsyncSocket classes.

Edit:

I've tried using a non-existent host, and I get the socket error:

WSAEINVAL (10022) Invalid argument

My next attempt was to use Alexander's suggestion of connecting to a different port, e.g. 81 (on my own server though). That worked great. Exactly the same as a dropped connection (60 second wait, then error). Thank you!

Answer 1

There are services available which allow you to artificially create origin timeouts by calling an API where you specify how long the server will take to respond. Server Timeout on macgyver is an example of such a service.

For example if you wanted to test a request that takes 15 seconds to respond you would simply make a post request to the macgyver API.

JSON Payload:

{
    "timeout_length": 15000
}

API Response (After 15 seconds):

{
    "response": "ok"
}

Server Timeout program on macgyver
https://askmacgyver.com/explore/program/server-timeout/3U4s6g6u

Answer 2

How about a software solution:

Install SSH server on the application server. Then, use socket tunnel to create a link between your local port and the remote port on the application server. You can use ssh client tools to do so. Have your client application connect to your mapped local port instead. Then, you can break the socket tunnel at will to simulate the connection timeout.

Answer 3

For me easiest way was adding static route on office router based on destination network. Just route traffic to some unresponsive host (e.g. your computer) and you will get request timeout.

Best thing for me was that static route can be managed over web interface and enabled/disabled easily.

Answer 4

Connect to an existing host but to a port that is blocked by the firewall that simply drops TCP SYN packets. For example, www.google.com:81.

Answer 5

You might install Microsoft Loopback driver that will create a separate interface for you. Then you can connect on it to some service of yours (your own host). Then in Network Connections you can disable/enable such interface...

Answer 6

Depending on what firewall software you have installed/available, you should be able to block the outgoing port and depending on how your firewall is setup it should just drop the connection request packet. No connection request, no connection, timeout ensues. This would probably work better if it was implemented at a router level (they tend to drop packets instead of sending resets, or whatever the equivalent is for the situation) but there's bound to be a software package that'd do the trick too.