A week or so ago I met a very nice Freenoder staffer in the #bitcoin and #bitcoin-dev channels. He told me that the #bitcoin channel turned up on Freenode’s radar as it looks like a Botnet Command and Control channel, but after I explained to him how Bitcoin works and why they need IRC, he said that the channel at it’s current size is not a problem.
However, this got me thinking and later this week I also discussed the topic on IRC, and I came to the conclusion, that IRC is the wrong method for bootstrapping, especially in it’s current form. At the moment, each client will connect to IRC and stay connected. Using /who and join messages, the client will connect to the found IPs on port 8333 as a bootstrapping method. However, the clients internally also talk to each other and broadcast new nodes via the Bitcoin protocol. Still, they are always online in IRC. This has various disadvantages:
IRC connectivity is necessary for bootstrapping (firewalls often block it and Freenode blocks TOR)
There is a single point of failure (Freenode)
We are leeching Freenode’s services instead of using our own infrastructure. Many servers actually disallow bot connections in their MOTDs.
Minor point: The additional protocol inside Bitcoin brings extra complexity
There is already a list of permanently-on Bitcoin IPs around in this forum, which is a nice idea, but not very scalable, thus I propose the following solution: Gnutella and MUTE face very similar bootstrapping problems. To solve them, they rely on a list of “Gnutella Webcaches”. Those webcaches are run by volunteers on simple PHP servers and a master list of them is distributed with each Gnutella/MUTE release. When a client wants to join the network, it asks one or two of the Webcaches via HTTP for a list of other nodes and also gets added to that list (which is usually a list of the last X clients seen). Every few hours (or days) a running client reconnects to the webcache to tell it, that it is still alive and does not have to be deleted from the list. I suggest, that the same thing is implemented for Bitcoin. Volunteers could run those webcaches on cheap PHP webspace and tell their URL to Satoshi or Sirius, who in turn could add the list to each release. This would allow users running behind a restrictive firewall or TOR to use Bitcoin without manually finding other nodes, and it is a much more scalable approach. (As a bonus we could remove those HTTP calls to whatismyip.com or similar sites).
Of course, there might be a better idea for bootstrapping Bitcoin and I would love to hear it. Or maybe suggestions for the Webcache idea. Please post them here!
Thanks soultcer for talking with the Freenode staffer. Good to know it’s OK at the current size, and now they know who we are. They’re supportive of projects like TOR so I hope they would probably be friendly to us. We don’t want to overstay our welcome. If we get too big, then by the same token, we’re big enough that we don’t need IRC anymore and we’ll get off.
We only needed IRC because nobody had a static IP. In the early days there were some steady supporters, but they all had pool-allocated IPs that change every few days. IRC was only intended as a temporary solution. Bitcoin’s built-in addr system is the main solution.
Bitcoin can get the list of IPs from any bitcoin node. In that sense, every node serves as a directory server.
When there are enough static IP nodes to have a good chance that at least one will still be running by the time the current version goes out of use, we can preprogram a seed list.
How do you think we should compile the seed list? Would it be OK to create it from the currently connected IPs that have been static for a while?
BTW, if we want to supplement by deploying separate directory server software, may I suggest IRC? IRC is a good directory server (I’ve heard it has other uses too), and there are mature IRC server implementations available that anyone can run. 🙂 Bitcoin’s IRC client implementation is already thoroughly tested.
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