On 8 Apr 2018, at 20:23, Felix zwiebel@quantentunnel.de wrote:

Happy today

Since November my ISP and I received a hand full of abuses for a non-exit. It is about scanning ports and addresses of a certain let's say victim ISP. I received one other abuse with another server.

For now I kindly want to ask if some operator received similar abuses for non-exits ? [1]

Under my perspective it could be:

• ip-spoofing. A third entity uses my ip and sends sync requests to the

victim. There will never be a statefull connection, but the victim feels offended. As result the only one who gets trouble is me.

• I got hacked (Uhh, don't like these words) which I suspect is not the

case. Then statefull connections are possible and by scanning etc the attacker interfers the victim. We should not discuss this here.

• There is some way out of the code which enables an attacker to perform

solicited or unsolicited interference. Like [2] or not known or whatever. It is difficult to discuss with my ISP because the world expects the non-exits connect only inside the Tor network and onion services.

Yes, people can use non-exit relays to port scan.

I'll quote my original email, which you have as [2]:

Receiving unsolicited TCP connections is a normal part of running a server on the Internet. And anyone who sends unsolicited spammy emails in response lacks a sense of irony.

But maybe we could change the Tor relay code to make failed circuits less useful for scanning?

We should check that we are returning the same reason for every non-relay port and IP, regardless of whether the IP exists, the port is open, or the port does TLS.

We could delay failure responses for a random interval.

Some facts:

• The victim ISP hosts no relay
• The relays are guards and potentially fallbacks (fallback and

non-fallback share an ip)

• I firewall blocked (outbound) all victim ISPs subnets. I logged some

outbound trials but this could not stop the abuses. Why? May-be the victim ISP has changing ip ranges which usually happens from time to time or I do not know their subnets completely. Interesting was that one destination ip was x.x.x.0 which is subnet zero.

Now the subnet routing is classless, zero is a valid address. It's typically used for the gateway or network address, but that's not required:

https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#IPv4_CIDR_block...

• Currently I firewall block (inbound) all victim ISPs subnets and found

log entries scanning (syn) my server on a non Tor port. Before blocking inbound, was there a way that someone from the vicitm ISP ip range can drive my relay (not server) to act like an offender back to the victims ISP?

They can run a tor client, connect to your relay, and tell it to connect to another IP address as if it is a relay. That's a standard part of the tor protocol via your relay's ORPort.

So there's no need to block inbound, and it won't solve this issue.

Pretty weired stuff but please swarm help! I apologize for my may-be foolish thoughts and please don't hit me too hard, though.

[1] [tor-relays] abuse email for non-exit relay (masergy) https://lists.torproject.org/pipermail/tor-relays/2017-September/013030.html

[2] Re to [1] https://lists.torproject.org/pipermail/tor-relays/2017-September/013041.html

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