Spec should change: stop requiring Tor relays to support old link versions

In our spec, we have

   All new relay implementations of the Tor protocol MUST support
   backwards-compatible renegotiation

But the v3 link handshake came out in Tor 0.2.3.6-alpha. That's certainly older than any relays. Is it older than any clients that we expect to work?

Step 0 in phasing out old link versions would be to admit in tor-spec that supporting them is not a MUST. I'd say we're ready to do this one any time. We could put v3 as the minimum you MUST implement, or we might pick v4, since it came out in 0.2.4.11-alpha, and that's pretty old now too.

Step 1 in phasing out old link versions would be to actually remove the code from mainline Tor. That's legacy/trac#9476 (moved).

changed milestone to %Tor: unspecified in legacy/trac

added 032-unreached in Legacy / Trac component::core tor/tor in Legacy / Trac milestone::Tor: unspecified in Legacy / Trac parent::9476 in Legacy / Trac priority::medium in Legacy / Trac severity::normal in Legacy / Trac status::new in Legacy / Trac type::enhancement in Legacy / Trac labels

Trac:
Username: Insolsence
Cc: N/A to ishbir@ishbir.com

Depends on legacy/trac#9476 (moved), though I'm not sure how much is left to do there.

Agreed that a spec patch comes first, and then comes testing of what happens when old Tors hit the new behavior.

In light of legacy/trac#9476 (moved), I'm going to change this ticket to be only about the spec change.

Trac:
Description: In our spec, we have

   All new relay implementations of the Tor protocol MUST support
   backwards-compatible renegotiation

But the v3 link handshake came out in Tor 0.2.3.6-alpha. That's certainly older than any relays. Is it older than any clients that we expect to work?

Step 0 in phasing out old link versions would be to admit in tor-spec that supporting them is not a MUST. I'd say we're ready to do this one any time. We could put v3 as the minimum you MUST implement, or we might pick v4, since it came out in 0.2.4.11-alpha, and that's pretty old now too.

Step 1 in phasing out old link versions would be to actually remove the code from mainline Tor. In preparation, we should try to figure out which Tor client versions are still in use today, and which ones still happen to work with the current network, and figure out in what time frame we'll be ok breaking those old Tor clients.

to

In our spec, we have

   All new relay implementations of the Tor protocol MUST support
   backwards-compatible renegotiation

But the v3 link handshake came out in Tor 0.2.3.6-alpha. That's certainly older than any relays. Is it older than any clients that we expect to work?

Step 0 in phasing out old link versions would be to admit in tor-spec that supporting them is not a MUST. I'd say we're ready to do this one any time. We could put v3 as the minimum you MUST implement, or we might pick v4, since it came out in 0.2.4.11-alpha, and that's pretty old now too.

Step 1 in phasing out old link versions would be to actually remove the code from mainline Tor. That's legacy/trac#9476 (moved).
Summary: Time to retire old link versions? to Time to not require Tor relays to support old link versions?

Replying to arma:

... the v3 link handshake came out in Tor 0.2.3.6-alpha. That's certainly older than any relays. Is it older than any clients that we expect to work?

We don't expect clients older than 0.2.4.26 or 0.2.5.11 to work: they don't believe enough current directory authority identities.

arma and I did the exact analysis by email the last time we dropped a directory authority, then posted it to tor-project:

Constraint 6: Tor versions before 0.2.8.1-alpha don't believe in
dannenberg's current v3 identity key, and Tor versions before 0.2.4.26
or 0.2.5.11 don't believe in longclaw at all. The dannenberg issue can
be solved by having dannenberg resume voting with its legacy v3 identity
key (I don't know why it stopped -- maybe it never started?), and the
longclaw issue can be solved by declaring that versions that old don't
matter to us.

https://lists.torproject.org/pipermail/tor-project/2016-July/000491.html

So we can declare v4 the only required version, if we like.

Mark a large number of tickets that I do not think we will do for 0.3.2.

Trac:
Keywords: N/A deleted, 032-unreached added
Milestone: Tor: 0.3.2.x-final to Tor: unspecified

Trac:
Parent: N/A to legacy/trac#9476 (moved)
Keywords: N/A deleted, N/A added

Trac:
Keywords: N/A deleted, N/A added

We have a potential fast zombie problem blocking us from ripping out the actual code (though that ship might have sailed some years ago), but in any case we could, any time we like, change the spec to say that relays don't need to support the old design.

Trac:
Summary: Time to not require Tor relays to support old link versions? to Spec should change: stop requiring Tor relays to support old link versions

moved from legacy/trac#22251 (moved)

added Feature label and removed 1 deleted label

removed 1 deleted label

added Proposal Ideas label

removed milestone

moved from tor#22251 (moved)

removed Proposal Ideas label

added Icebox label