Fix failing NAT simulation tests

[tegefaulkes]

Specification

Recently the NAT tests have been failing. It seems to be from the network domain changes but i'm unsure when exactly the problem started. So far I've looked into the problem and the failure seems to be that we're failing to connect to the target agent using a nodePing. The errors in the code seems to be consistent with the expected operation where we can't connect to a target. But the tests expect us to be able to connect.

Starting from the DMZ tests, we have all the network name spacing setup but no IP table rules mimicking a NAT. the expected outcome is that we can connect to the agent by trying to connect through the virtual router in the namespace. With this setup there should be nothing impeding the connection but we are still failing to connect.

Given the compexity of the tests, there are quite a few places this could be failing at. It could be the networking or nodes connection code causing the problem. At this stage that seems unlikely since this code work in all other tests but the NAT tests. I could be the network namespace setup causing the problem. If the networks doesn't work as expected here we could be failing to connect.

Additional context

• Comment chain starting from ci: merge staging to master #474 (comment)

Tasks

• 1. Check that the networking and nodes domain code are working as expected.
• 2. Check that the network name spacing setup is working as expected.
• 3. Try to find the root cause of the problem.

[tegefaulkes]

I've reviewed the network and nodes code relating to this. So far as I can tell it's working as expected if you were unable to connect to the target. So at this point I'm leaning towards it being an issue with how the NAT tests are setting up the network and name spacing.

Next steps to try would be

1. Walk down the staging commits and isolate the commit that caused the problem. There was mention of the nix packages getting updated. Could that be the cause?
2. Check that the name spacing setup in the NAT tests are working as expected. We can add a sanity test where we do a netcat in place of the agent communication. That should absolve or implicate the agents depending on the result.

[tegefaulkes]

this should take at most a day to complete. could be sooner or longer depending what we run into. Network issues like these have been head scratchers in the past so we'll see.

[CMCDragonkai]

We'll put this on the backburner while we bring up the testnet integration work for this week. The reason for this failing may be revealed through our manual testing of the testnet.

[CMCDragonkai]

We may want to move these NAT simulation tests into https://gitlab.com/MatrixAI/Engineering/Polykey/Polykey-Simulation if they involve too much infrastructure.

I think they do use quite a bit atm.

[CMCDragonkai]

According to @tegefaulkes these are now passing in #474. So I'll close this. Reopen if this still occurs, maybe the NAT infrastructure isn't to blame here.