[tor-relays] How to reduce tor CPU load on a single bridge?

[Gary C. New]

On Saturday, January 29, 2022, 9:46:59 PM PST, David Fifield <david at bamsoftware.com> wrote:
 
>> > I'm not using nyx. I'm just looking at the bandwidth on the network interface.

>> If you have time, would you mind installing nyx to validate observed similarities/differences between our loadbalanced configurations?

> I don't have plans to do that.
I appreciate you setting expectations.

>> > > I'm glad to hear you feel the IPv6 reporting appears to be a false-negative. Does this mean there's something wrong with IPv6 Heartbeat reporting?

>> > I don't know if it's wrong, exactly. It's reporting something different than what ExtORPort is providing. The proximate connections to tor are indeed all IPv4.

>> I see. Perhaps IPv6 connections are less prolific and require more time to ramp?

> No, it's not that. The bridge has plenty of connections from clients that use an IPv6 address, as the bridge-stats file shows:

> ```plain
> bridge-ip-versions v4=15352,v6=1160
> ```

> It's just that, unlike a direct TCP connection as the the case with a guard relay, the client connections pass through a chain of proxies and processes on the way to the tor: client → Snowflake proxy → snowflake-server WebSocket server → extor-static-cookie adapter → tor. The last link in the chain is IPv4, and evidently that is what the heartbeat log reports. The client's actual IP address is tunnelled, for metrics purposes, through this chain of proxies and processes, to tor using a special protocol called ExtORPort (see USERADDR at https://gitweb.torproject.org/torspec.git/tree/proposals/196-transport-control-ports.txt). It looks like the bridge-stats descriptor pays attention to the USERADDR information and the heartbeat log does not, that's all.
Ah... Gotcha. Thank you for clarifying.
>> After expanding my reading of your related "issues," I see that your VPS provider only offers up to 8 cores. Is it possible to spin-up another VPS environment, with the same provider, on a separate VLAN, allowing route/ firewall access between the two VPS environments? This way you could test loadbalancing a Tor Bridge over a local network using multiple virtual environments.
> Yes, there are many other potential ways to further expand the deployment, but I do not have much interest in that topic right now. I started the thread for help with a non-obvious point, namely getting past the bottleneck of a single-core tor process. I think that we have collectively found a satisfactory solution for that. The steps after that for further scaling are relatively straightforward, I think. Running one instance of snowflake-server on one host and all the instances of tor on a nearby host is a logical next step.

Understand. I appreciate the work you have done and the opportunity to compare and contrast Loadbalanced Tor Bridges vs Loadbalanced Tor Relays.
Please update the tor-relays mailing-list with any new findings related to subversion of the onion keys rotation.
Excellent Work!
Respectfully,

Gary—
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