#33222: Prop 311: 4.2. Checking IPv6 ORPort Reachability
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Reporter: teor | Owner: teor
Type: defect | Status: assigned
Priority: Medium | Milestone: Tor: 0.4.4.x-final
Component: Core Tor/Tor | Version:
Severity: Normal | Resolution:
Keywords: ipv6, prop311 | Actual Points:
Parent ID: #33221 | Points: 6
Reviewer: | Sponsor:
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Description changed by teor:
Old description:
> 4.2. Checking IPv6 ORPort Reachability
>
> We propose that testing relays (and bridges) select some IPv6 extend-
> capable
> relays for their reachability circuits, and include their own IPv4 and
> IPv6
> ORPorts in the final extend cells on those circuits.
>
> The final extending relay will extend to the testing relay:
> * using an existing authenticated connection to the testing relay
> (which may be over IPv4 or IPv6), or
> * over a new connection via the IPv4 or IPv6 ORPort in the extend cell.
>
> The testing relay will confirm that test circuits can extend to both its
> IPv4 and IPv6 ORPorts.
>
> 4.2.1. Selecting the Final Extending Relay
>
> IPv6 ORPort reachability checks require an IPv6 extend-capable relay as
> the second-last hop of reachability circuits. (The testing relay is the
> last hop.)
>
> IPv6-extend capable relays must have:
> * Relay subprotocol version 3 (or later), and
> * an IPv6 ORPort.
> (See section 5.1 for the definition of Relay subprotocol version 3.)
>
> The other relays in the path do not require any particular protocol
> versions.
>
> 4.2.2. Extending from the Second-Last Hop
>
> IPv6 ORPort reachability circuits should put the IPv4 and IPv6 ORPorts in
> the extend cell for the final extend in reachability circuits.
>
> Supplying both ORPorts makes these extend cells indistinguishable from
> future client extend cells.
>
> If reachability succeeds, the testing relay (or bridge) will accept the
> final extend on one of its ORPorts, selected at random by the extending
> relay (see section 3.2.1).
>
> 4.2.3. Separate IPv4 and IPv6 Reachability Flags
>
> Testing relays (and bridges) will record reachability separately for IPv4
> and IPv6 ORPorts, based on the ORPort that the test circuit was received
> on.
New description:
4.2. Checking IPv6 ORPort Reachability
We propose that testing relays (and bridges) select some IPv6 extend-
capable
relays for their reachability circuits, and include their own IPv4 and
IPv6
ORPorts in the final extend cells on those circuits.
The final extending relay will extend to the testing relay:
* using an existing authenticated connection to the testing relay
(which may be over IPv4 or IPv6), or
* over a new connection via the IPv4 or IPv6 ORPort in the extend cell.
The testing relay will confirm that test circuits can extend to both its
IPv4 and IPv6 ORPorts.
4.2.1. Selecting the Final Extending Relay
IPv6 ORPort reachability checks require an IPv6 extend-capable relay as
the second-last hop of reachability circuits. (The testing relay is the
last hop.)
IPv6-extend capable relays must have:
* Relay subprotocol version 3 (or later), and
* an IPv6 ORPort.
(See section 5.1 for the definition of Relay subprotocol version 3.)
The other relays in the path do not require any particular protocol
versions.
4.2.2. Extending from the Second-Last Hop
IPv6 ORPort reachability circuits should put the IPv4 and IPv6 ORPorts in
the extend cell for the final extend in reachability circuits.
Supplying both ORPorts makes these extend cells indistinguishable from
future client extend cells.
If reachability succeeds, the testing relay (or bridge) will accept the
final extend on one of its ORPorts, selected at random by the extending
relay (see section 3.2.1).
4.2.3. Separate IPv4 and IPv6 Reachability Flags
Testing relays (and bridges) will record reachability separately for IPv4
and IPv6 ORPorts, based on the ORPort that the test circuit was received
on.
From proposal 311, section 4.2:
https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-
ipv6-reachability.txt#n283
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