Prop 311: 4.2. Implement IPv6 ORPort Reachability Self-Tests
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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections from other relays
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using port forwarding.) Make sure the cell was received on an inbound OR connection, that is authenticated to another relay.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections from other relays to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
Activity
changed milestone to %Tor: 0.4.5.x-final
Trac:
Parent Ticket: #33221 (moved)
Child Ticket(s): #33227 (moved)Trac:
Description: 4.2. Checking IPv6 ORPort ReachabilityWe 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.
to
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
Update the end of the description with a robust self-test design.
Here are some additional notes:
Once we validate the created cell, we have confirmed that the final remote relay has our private keys.
If our relay was set up using a copy of another relay's keys, then we might have connected to that relay. We could test that the create cells we receive match create cells that we have actually sent. But that seems unnecessary, because duplicate keys are rare. (And authorities enforce key uniqueness in the consensus.)
At best, it would provide a warning for operators who have accidentally duplicated their keys. (Operators can override these checks using AssumeReachable.)
Trac:
Description: 4.2. Checking IPv6 ORPort ReachabilityWe 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
to
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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using NAT.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
We can start work on this ticket now.
We can start working on:
- circuit-building, and
- separate IPv4 and IPv6 reachability flags.
We can open another ticket for the Relay protocol version checks, or move that work into the protocol version ticket #33226 (moved).
Here's an initial PR, to show that the IPv6 extend and reachability code can work:
- don't merge: https://github.com/torproject/tor/pull/1874
It sends IPv4-only and IPv6-only extends on reachability circuits, to any third hop.
Here's what we need to do before we merge:
- 4.2.1 Selecting the Final Extending Relay (this ticket)
-
- Declare Support for Subprotocol Version "Relay=3" (#33226 (moved))
-
- unit tests
- changes files
Then we can iterate on the remaining work.
I'd like an initial review on this code. But it's not blocking anything for me. I have a big list of tasks I still need to do :-)
Trac:
Reviewer: N/A to nickm
Actualpoints: N/A to 1.1Notes about some false positives in the reachability checks.
Trac:
Description: 4.2. Checking IPv6 ORPort ReachabilityWe 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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using NAT.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
to
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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using NAT.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
Say "port forwarding" for clarity
Trac:
Description: 4.2. Checking IPv6 ORPort ReachabilityWe 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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using NAT.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
to
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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using port forwarding.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
Thanks for the review!
I might be a bit busy next week with non-work tasks, but I'll try to do at least one revision.
Replying to teor:
It sends IPv4-only and IPv6-only extends on reachability circuits, to any third hop.
Here's what we need to do before we merge:
- 4.2.1 Selecting the Final Extending Relay (this ticket)
-
- Declare Support for Subprotocol Version "Relay=3" (#33226 (moved))
-
- unit tests
- changes files
Then we can iterate on the remaining work.
My next priority is to:
- Separate tor's IPv4 and IPv6 reachability flags (#34067 (moved))
So we know that we're actually getting IPv6 connections. (I'm pretty sure we are now, but we don't want to accidentally break them.)
- 4.2.1 Selecting the Final Extending Relay (this ticket)
I've done another revision.
This branch is not ready for merge yet, but the basic design and functionality should be there. I still have to:
Replying to teor:
- 4.2.1 Selecting the Final Extending Relay (this ticket)
-
- Declare Support for Subprotocol Version "Relay=3" (#33226 (moved))
-
- unit tests
- changes files
Then I think we can safely merge.
Since this PR is getting big, I'd like to leave any other significant changes for a later PR and ticket:
Replying to teor:
My next priority is to:
- Separate tor's IPv4 and IPv6 reachability flags (#34067 (moved))
So we know that we're actually getting IPv6 connections. (I'm pretty sure we are now, but we don't want to accidentally break them.)
The extend_info changes in #34069 (moved), and dual-stack EXTEND2 cells aren't a high priority. The code will work either way.
Trac:
Status: assigned to needs_review- 4.2.1 Selecting the Final Extending Relay (this ticket)
Spec change: let's check for inbound create cells from other relays (rather than relays or clients)
Trac:
Description: 4.2. Checking IPv6 ORPort ReachabilityWe 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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using port forwarding.) Make sure the cell was received on an inbound OR connection.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
to
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.
Here is a reliable way to do reachability self-tests for each ORPort:
- Check for create cells on inbound ORPort connections from other relays
Check for a cell on any IPv4 and any IPv6 ORPort. (We can't know which listener(s) correspond to the advertised ORPorts, particularly when using port forwarding.) Make sure the cell was received on an inbound OR connection, that is authenticated to another relay.
- Check for created cells from testing circuits on outbound OR connections
Check for a returned created cell on our IPv4 and IPv6 self-test circuits. Make sure those circuits were on outbound OR connections.
By combining these tests, we confirm that we can:
- reach our own ORPorts with testing circuits
- send and receive cells via inbound OR connections from other relays to our own ORPorts
- send and receive cells via outbound OR connections to other relays' ORPorts
This isn't a perfect test, there are a few false positives:
- relays with multiple IPv4 or IPv6 ORPorts, where only some ports are reachable:
- (this configuration is uncommon, but multiple ORPorts are supported)
- the final extend cell contains the advertised IPv6 address of the self-testing relay
- if the extending relay already has a connection to an old but working ORPort, it may use that connection instead
- so these tests can pass, even when the advertised ORPort is unreachable
- relays whose keys have been copied from another relay in the consensus, for similar reasons
- this configuration is rare and unsupported
From proposal 311, section 4.2: https://gitweb.torproject.org/torspec.git/tree/proposals/311-relay-ipv6-reachability.txt#n283
All the changes on github, up through 492c512, look fine to me.
I think we could delay #33226 (moved) till after this merges if you want to, but we can't delay the unit tests (and integration testing).
Replying to nickm:
All the changes on github, up through 492c512, look fine to me.
I think we could delay #33226 (moved) till after this merges if you want to, but we can't delay the unit tests (and integration testing).
I'd like to declare Relay=3 so this new code can check for it. Otherwise it will send IPv6 extends to a bunch of older relays that don't handle them. That's not harmful in any way, but it may be confusing.
And then unit tests :-)
I've updated the PR with the changes from #33226 (moved), and some refactoring:
- incomplete: https://github.com/torproject/tor/pull/1874
It took a bit longer than I thought, I forgot how tricky node filters are. (I needed to change the protocol versions, circuit-level flags, and node-level flags.)
That's all the features, but it still needs unit tests and changes file.
Chutney already does integration tests:
- using tor's
make test-network-alllocally, and - via Travis CI on macOS (dual-stack) and Linux (IPv4 only).
Trac:
Actualpoints: 1.1 to 3I just pushed a final refactor that cleans up a bunch of duplicate code. But I think it's best that we deal with the latest refactor commits in another ticket. (They shouldn't hold up merging this feature.) So I opened #34200 (moved) for the refactor, and split the branch.
The (shorter) PR still needs unit tests and changes files.
The stem tests will fail due to:
- https://github.com/torproject/stem/issues/63 Reverting to the most recent stem release, or stem commit 13e401d, should resolve this issue.
I have pushed some extra tests and changes files:
This branch also fixes the following Rust protover bugs in master:
- #34248 (moved): add HSIntro=5 in Rust
- #34251 (moved): fix error handling in Rust protover is supported I've left those tickets open, because we need to backport those changes.
Here are the features and functions that don't have unit tests:
- launch IPv6 ORPort self-test circuits
- fmt_addr32_port()
- fmt_af_family() - refactoring
- fmt_addr_family() - refactoring
- router_get_orport()
- extend_info_from_router()
- router_do_orport_reachability_checks()
- router_do_dirport_reachability_checks() - minor modifications and refactoring
- router_do_reachability_checks() - minor modifications and refactoring
- inform_testing_reachability() - minor modifications and refactoring
- when launching IPv6 ORPort self-test circuits, make sure that the last hop supports IPv6 extends
- node_supports_initiating_ipv6_extends()
- node_supports_accepting_ipv6_extends()
- router_add_running_nodes_to_smartlist() - added IPv6 extend check
These tests should be much easier to write on top of the refactor in #34200 (moved).
This code runs in chutney's IPv6 networks, which are part of Tor's CI. But chutney doesn't fully test IPv6 reachability yet. Chutney will test more of this code, when we split tor's IPv4 and IPv6 reachability flags in #34067 (moved).
Trac:
Actualpoints: 3 to 4-
This is merged to master with #34200 (moved); now cleaning up child tickets.
mentioned in issue #33225 (moved)
mentioned in issue #33225 (moved)
mentioned in issue #33226 (moved)
mentioned in issue #33227 (moved)
mentioned in issue #33229 (moved)
mentioned in issue #33407 (moved)
mentioned in issue #33581 (moved)
mentioned in issue #33582 (moved)
mentioned in issue #34037 (moved)
mentioned in issue #34067 (moved)
mentioned in issue #34068 (moved)
mentioned in issue #34069 (moved)
mentioned in issue #34137 (moved)
mentioned in issue #34200 (moved)
mentioned in issue #34248 (moved)
mentioned in issue #34251 (moved)
mentioned in issue #34412 (moved)
mentioned in issue #33221 (moved)
mentioned in issue tpo/core/chutney#33229 (closed)
mentioned in issue tpo/core/chutney#33581 (closed)
mentioned in issue tpo/core/chutney#34037