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Date: Tue, 31 Jan 2012 13:50:13 +0000
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To: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] CAddrMan: Stochastic IP address manager
Precedence: list

We split IRC among all those channels to handle the load when there were =
60k clients.. the ideal thing would be some kind of dynamic sizing, and =
this applies to the number of outbound connections and transaction =
relaying logic too.. the same values that work for 1k clients don't work =
as well for 50k.  It is difficult to get this kind of thing tuned =
correctly, especially with the added complexity of potentially malicious =
nodes.

I think the observed isolation problems, with or without IRC, are simply =
due to there not being many bitcoin nodes leaving/joining the network.  =
The ones that are stable are happy with their 8 connections or whatever =
they're set to, and they're just relaying.  There are only about 5k =
clients on IRC now.. it would probably work to go back to the single =
channel model as (at least from the IRC point of view) the usage is =
declining not growing.  Maybe people are just turning off IRC though.  =
IRC works well with many channels having a few clients each, not with =
one channel having many clients.  We considered probing bitcoin clients =
to see if they're listening and favoring those clients in the WHO =
response, kind of like the DNS booters, but nobody got around to doing =
it.

Still, I think it's good to have a bunch of different ways to bootstrap =
in case one or the other is broken/poisoned.

Laszlo



On Jan 31, 2012, at 2:57 AM, Gregory Maxwell wrote:

> On Mon, Jan 30, 2012 at 9:05 PM, Gavin Andresen =
<gavinandresen@gmail.com> wrote:
>> I've also been wondering if it is time to remove the IRC =
bootstrapping
>> mechanism; it would remove a fair bit of code and we'd stop getting
>> reports that various ISPs tag bitcoin as malware.  When testing the
>> list of built-in bootstrapping IP addresses I always connect fairly
>> quickly, and the DNS seeding hosts seems to be working nicely, too.
>=20
> S=CE=BF=E2=80=94 would we remove it or leave it deactivated as a =
fallback users can turn on?
>=20
> I have two different thoughts about IRC depending on the answer.
>=20
> I think it's important that we have more mechanisms then just DNS and
> hardcoded seednodes.
>=20
> This is important because the mechanisms we have are all pretty
> subject to blocking. Now=E2=80=94 before you say it=E2=80=94 Bitcoin =
isn't intended to
> be blocking resistant (combine it with Tor and Tor anti-censorship
> tools) but by making blocking a bit harder we discourage people from
> even trying, even if we're not seriously in the anti-blocking
> business=E2=80=94 and it gives bitcoin users more confidence because =
there is
> a bit less FUD  "What if your ISP blocks it?? It uses DNS! Someone
> might take away the domains! SOPA PIPI ACTA CIPA Alakazam".
>=20
> Is the fact that users can addnodes / addr.txt enough of an
> alternative to address this?   _If so_, then removing it is a good
> idea.  I volunteer to maintain a multi-channel joining node for the
> foreseeable future to avoid letting old clients get partitioned
> (several people need to do this).
>=20
> An area where I think our mechanisms are inadequate absent IRC is
> announcing new nodes. I had a new listener up for over a week recently
> and was basically getting no inbound until I enabled IRC.   I
> volunteer to do some measurement of this (e.g. bring up some nodes
> with no irc and find out how long until sipa hears about them).  If
> DNS seeds are slow to learn about new nodes we may need to add a
> simple UDP announcement feature.
>=20
> In any case, I hadn't been thinking that we would completely remove
> IRC=E2=80=94 I was expecting us to keep IRC around but turned off.
>=20
> In particular I think it may be a little risky to turn off IRC at the
> same time as deploying addrman, because if addrman has unexpected bad
> behavior IRC is what may keep things going.  Obviously it should be
> well tested enough to feel confident, but belt-and-suspenders is the
> way to go.
>=20
>=20
> If we do keep in the long run I think it's important to _fix_ IRC.
> Right now it has some really stupid behavior which is highly
> pro-partitioning.
>=20
> */who only returns a few nodes, and because most idlers aren't
> actually working (no port forward) it's usually for there to be only a
> few that work. (I've never seen zero, but I've seen 1).
> *Other than who we only learn about nodes when they join. But the
> stable long lived nodes we need to hear about seldom rejoin. Nonuseful
> windows boxes go up and down a lot.
> *Nodes sit in a single channel forever. There are 100 of them.
> Especially with fewer clients on line nodes may be sitting alone with
> no correctly working nodes with them.
> *Nodes recently seen on IRC are highly promoted in the peer selection.
>=20
> So, here is an updated irc.cpp which I've been running (in various
> versions) for a while:
> http://people.xiph.org/~greg/irc.cpp
>=20
> It does the following things:
> * Only stays connected for a half hour
> * If its sure its not listening it uses a random nick so people won't
> try to connect
> * Reconnects if it needs more connections
> * If the node is actually listening (evidence by actual incoming
> connections) it reconnects on its own every 1-2 hours and joins two
> channels at random rather than one.
> (it doesn't change peer selection=E2=80=94 It's hard to be confident =
of the
> impact of that change. I think addrman makes it less of an issue)
>=20
> I've only not submitted it as a pull request because I haven't had a
> chance to test to my standards, and because I felt unsure about the
> future of IRC.
>=20
> I feel strongly that if we're going to keep IRC as a backup we should
> fix it. If we're not going to bother then thats fine=E2=80=94 but I =
think we
> need to think carefully if we're doing enough for bootstraping (with
> the points I made) without it.
>=20
> Certainly getting it off by default would be a good move. The botnet
> allegations are horrible.
>=20
> =
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