Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of bluematt.me
	designates 208.79.240.5 as permitted sender)
	client-ip=208.79.240.5; envelope-from=bitcoin-list@bluematt.me;
	helo=smtpauth.rollernet.us; 
From: Matt Corallo <bitcoin-list@bluematt.me>
To: bitcoin-development@lists.sourceforge.net
In-Reply-To: <CANEZrP1-BaNmKhSPXSe2sjH0-DPm62_=OQ_S6aCT3-nLdFLLGA@mail.gmail.com>
References: <CANEZrP1-BaNmKhSPXSe2sjH0-DPm62_=OQ_S6aCT3-nLdFLLGA@mail.gmail.com>
Content-Type: multipart/signed; micalg="pgp-sha1";
	protocol="application/pgp-signature";
	boundary="=-/8k+369dKwStOZeaoEy6"
Date: Wed, 03 Aug 2011 13:38:19 +0200
Message-ID: <1312371499.2322.14.camel@Desktop666>
Mime-Version: 1.0
Subject: Re: [Bitcoin-development] DNS seeds returning gone peers
Precedence: list


--=-/8k+369dKwStOZeaoEy6
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Wed, 2011-08-03 at 12:04 +0200, Mike Hearn wrote:
> This is expected to happen from time to time of course as it's
> inherently racy, but there are a lot of bad nodes appearing in the DNS
> seeds.

> $ nmap -oG /tmp/x -p 8333 `dig +short bitseed.bitcoin.org.uk
> dnsseed.bluematt.me bitseed.xf2.org`
> ...
> Nmap done: 48 IP addresses (25 hosts up) scanned in 9.80 seconds

> $ grep -c 'closed' /tmp/x
> 6

> So of 48 IPs returned only 19 are actually usable. This is slowing
> down peer bringup for the Android apps, which don't currently save the
> addresses of last-used peers (yes, I know we should fix this).
Its actually much, much less.  You forgot to grep for filtered, which
are also worthless and you didn't make an actual connection to the node,
meaning there is no way to tell if the node has its connection slots
full (a node which has the maximum connection count will ack a syn, but
will drop the connection after the first message, so nmap thinks the
port is open).
I just tested and I show 0 accepting from bitseed.xf2.org and 0 from
bitcoin.bitcoin.co.uk.  dnsseed.bluematt.me rotates every 2 minutes to
the most recently checked so it tends to be pretty good if you get it
right after a rotate, if you wait to long, those slots fill up quick.
>=20
> I was talking to a friend a few days ago about Bitcoin, he seemed
> interested. I'm hoping he might take on DNS seeding as a project. A
> custom DNS server that watches the network to find long-lived peers
> that run the latest version would be helpful for resolving this kind
> of thing.
Point him to https://github.com/TheBlueMatt/dnsseed it could use a bit
of cleanup, but it works.
If a different DNS Server were used to could pull directly from the
database in a more dynamic way it would probably work better too (it was
originally set up on MySQL and PowerDNS, but that is quite a resource
hog compared to SQLite and BIND, but the original backend is still there
and could work if you have a beefy enough server).

Matt

--=-/8k+369dKwStOZeaoEy6
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
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=dULe
-----END PGP SIGNATURE-----

--=-/8k+369dKwStOZeaoEy6--