Re: [bitcoin-dev] Planned Obsolescence

From: Matt Corallo <lf-lists@mattcorallo•com>
To: "Ethan Heilman" <eth3rs@gmail•com>,
	"Bitcoin Protocol Discussion"
	<bitcoin-dev@lists•linuxfoundation.org>,
	"Ethan Heilman via bitcoin-dev"
	<bitcoin-dev@lists•linuxfoundation.org>,
	"Jorge Timón" <jtimon@jtimon•cc>
Subject: Re: [bitcoin-dev] Planned Obsolescence
Date: Sun, 18 Dec 2016 10:34:43 +0000	[thread overview]
Message-ID: <10231F2A-32C3-4E19-934B-C83E595DDBEB@mattcorallo.com> (raw)
In-Reply-To: <CAEM=y+Ws-2_mpZQfE1BD8dnmkcBFsXK8Pd3ZvX=e9R_4bj4qng@mail.gmail.com>

One thing which hasn't been addressed yet in this thread is developer centralization. Unlike other applications we want to ensure that it's not only possible for users to refuse an upgrade, but easy. While this by no means lessens the retirement that users run up to date software for security reasons, finding the right line to draw is difficult. 

Matt

On December 15, 2016 2:44:55 PM PST, Ethan Heilman via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
>I assume this has been well discussed in at some point in the Bitcoin
>community, so I apologize if I'm repeating old ideas.
>
>Problem exploitable nodes:
>It is plausible that people running these versions of bitcoind may not
>be applying patches. Thus, these nodes may be vulnerable to known
>exploits. I would hope none of these nodes are gateway nodes for
>miners, web wallets or exchanges. How difficult would it be to crawl
>the network to find vulnerable nodes and exploit them? What percentage
>of the network is running vulnerable versions of bitcoind?
>
>Problem eclipsable nodes:
>Currently a bitcoind node disconnects from any node with a version
>below MIN_PEER_PROTO_VERSION. Such nodes become be ripe for an eclipse
>attack because they are partitioned from the newer nodes, especially
>when they are "freshly obsolete". I have not examined how protocol
>versioning works in detail so I could be missing something.
>
>One option could be that after a grace period:
>1. to still connect to obsolete nodes and even to transmit
>blockheaders,
>2. but to stop sending the full-blocks and transactions to these
>nodes, thereby alerting the operator that something is wrong and
>causing them to upgrade.
>It may make sense to create this as a rule, if your longest chain
>consists of only blockheaders and no one will tell you the
>transactions for over 1000 blocks you are obsolete, spit out an error
>message and shutdown.
>
>This would not address the issue of alt-coins which are forked from
>old vulnerable versions of bitcoind, but that is probably out of
>scope.
>
>On Thu, Dec 15, 2016 at 1:48 PM, Jorge Timón via bitcoin-dev
><bitcoin-dev@lists•linuxfoundation.org> wrote:
>> On Thu, Dec 15, 2016 at 4:38 AM, Juan Garavaglia via bitcoin-dev
>> <bitcoin-dev@lists•linuxfoundation.org> wrote:
>>> Older node versions may generate issues because some upgrades will
>make
>>> several of the nodes running older protocol versions obsolete and or
>>> incompatible. There may be other hard to predict behaviors on older
>versions
>>> of the client.
>>
>> Hard to predict or not, you can't force people to run newer software.
>>
>>> In order to avoid such wide fragmentation of "Bitcoin Core” node
>versions
>>> and to help there be a more predictable protocol improvement
>process, I
>>> consider it worth it to analyze introducing some planned
>obsolescence in
>>> each new version. In the last year we had 4 new versions so if each
>version
>>> is valid for about 1 year (52560 blocks) this may be a reasonable
>time frame
>>> for node operators to upgrade. If a node does not upgrade it will
>stop
>>> working instead of participating in the network with an outdated
>protocol
>>> version.
>>
>> When you introduce anti-features like this in free software they can
>> be trivially removed and they likely will.
>>
>>> These changes may also simplify the developer's jobs in some cases
>by
>>> avoiding them having to deal with ancient versions of the client.
>>
>> There's a simpler solution for this which is what is being done now:
>> stop maintaining and giving support for older versions.
>> There's limited resources and developers are rarely interested in
>> fixing bugs for very old versions. Users shouldn't expect things to
>be
>> backported to old versions (if developers do it and there's enough
>> testing, there's no reason not to do more releases of old versions,
>it
>> is just rarely the case).
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