Nolisten patch #11

With the current client it is impossible to start mulitple instances of bitcoin on one system, as they compete for the listen port. This patch adds a command line option to not accept bitcoin connection from outside.

This can be useful in some cases:

• Testing e-commerce software on the testnet with multiple clients on one machine (akin to paypal sandbox testing)
• When multiple users on one shared server want to run the bitcoin client
• As a primitive security measure

Of course it would be even better to specify a port to listen on on the command line, but as I understood the current protocol has no support for alternative ports, so this would be useless.

Could you post a [PULL REQUEST] about this on the Dev&Tech forum: http://www.bitcoin.org/smf/index.php?board=6.0

Until we figure out where we want to discuss pull requests (on the forum or maybe directly here), I figure it is best to do both.

I'm a little worried that if this feature gets popular the IRC channel and the 'addr' messages flying across the network might be overwhelmed with the IP addresses of clients that aren't listening. New nodes joining might then spend a long time trying and failing to connect.

I'd be more comfortable if the patch also taught the client NOT to advertise its own IP:port on the IRC channel or via 'addr' broadcasts.

I had originally made a forum post, with the patch attached, but the forum decided to eat it due to (invalid attachment type .patch). Then I found out about this feature :) But I'll make a new post and simply link here.

Valid issue about the IRC channel. I had considered that, and was under the impression that this if clause in net.cpp handled it (as in case of proxy or -connect, also no IRC connection should be made):

if (fUseProxy || mapArgs.count("-connect") || fNoListen)

Seems I was wrong.

Ah, I see the new commit (don't connect to IRC on -nolisten) was automatically added here.

Seems to me as trying to fix an intermediate problem, I'd much rather see a patch adding the ability to specify a listen port. But the patch to disable IRC bootstrapping seems nice.