Re: [tor-relays] Receiving abuse reports for Non-Exit Relay

In the past 24 hrs, I have been receiving complaints from my hosting provider that they're receiving hundreds of abuse reports related to port scanning. I have no clue why I'm all of the sudden receiving abuse reports when this non-exit relay has been online for months without issues. In addition, I have other non-exit relays hosted by the same provider with no issues and more across other providers.

I proceeded to reinstall the OS and reconfigure Tor. I was then quickly notified by my hosting provider again of more abuse reports all showing port 22 as target port.

I have not changed my torrc at all and it's still setup as a non-exit relay. No other applications/services were installed alongside Tor. Tor Metrics does not show the relay as Exit either.

It feels like Tor Exit Traffic is leaking through my non-exit relay?


   To me it seems like bogus or invalid reports. With certainity over 19 in 20. The picture simply does not fit port scanning.

  1. Not only middle relays, but exit nodes can only perform complete TCP connections. Port scanning usually involves a SYN or UDP scan, which is technically not possible to be done using any Tor node.

  2. Even if we assume somebody is hurting oneself by performing a full-connection TCP scan, you mention only one port is being reported. A port scan involves many ports. And this is not merely pedanticism regarding naming. The detection of a port scan relies on this. In other words: there is no way to classify traffic as a port scan, if only one port is affected.

   Since only port 22 is affected and 22 is not a common port for Tor relays, you may simply block egress traffic to this port altogether. The same as IP address ranges for which reports come. If the reports continue coming, you can be almost sure they are false. The little uncertainity remains for some attacker having root (or above-root) access to your machine, but this is not coming from your Tor relay.

   Before blocking IP address ranges, check if they are not relays. I do not want to make positive statements about one trying to affect Tor network, but such a possibility should also not be excluded without checking.