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[tor-relays] Re: moria1 unreachable from AS202306



On 18.08.2025 03:08 Roger Dingledine via tor-relays
<tor-relays@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Sun, Aug 17, 2025 at 08:13:45AM +0200, Marco Moock via tor-relays
> wrote:
> > Hello!
> > 
> > I cannot communicate with moria1 from 78.153.140.44 and it cannot
> > reach my system. I can communicate with the rest of the world.
> > 
> > For me, it looks like a firewall is blocking it, as traceroute
> > clearly indicates a different behaviour for ICMP echo request and
> > TCP.  
> 
> I think we have two problems here:
> 
> (A) You seem to have a firewall on your side which is blocking TCP
> connections to moria1's IP address. You could compare traceroutes to
> 128.31.0.24 (same box, different address) to see if some of them get
> farther.

No, I can reach other systems properly, the relay runs fine for months.
As you can see from my traceroute, the issue is not local at my hoster.

> Some of these blocks around the internet of 128.31.0.39 come from the
> ddos events of 2021, where some jerk tried to overload the directory
> authorities by requesting directory info via Tor circuits (i.e. via
> exit relays). See this ticket which was a theoretical issue for many
> years until suddenly it was a concrete issue:
> https://bugs.torproject.org/tpo/core/tor/2667

Can this be liftet again?

> (B) But it's worse than that! All of MIT seems to null-route your
> address too. That is, here is the traceroute from one of the MIT
> shared dialups (not my computer there in particular):

Why don't they emit ICMP no route/route rejected in this case at least
for their internally originating traffic?

It sees they either null-route or block my address/net as a destination.
Can someone from them investigate that?

> ~> traceroute 78.153.140.44  
> traceroute to 78.153.140.44 (78.153.140.44), 30 hops max, 60 byte
> packets 1  18.9.64.3 (18.9.64.3)  0.643 ms  0.717 ms  0.772 ms
>  2  BACKBONE-RTR-2-OC11-RTR-1.MIT.EDU (18.0.194.85)  1.718 ms  1.777
> ms  1.729 ms 3  DMZ-RTR-2-BACKBONE-RTR-2.MIT.EDU (18.0.162.1)  0.819
> ms  0.885 ms  0.842 ms 4  * * *
>  5  * * *
>  6  * * *
>  7  * * *
>  8  * * *
>  9  * * *
> 10  * * *
> [...continues on for 20 more failed hops]
> 
> I believe this is because MIT auto pulls in the spamhaus blocklists
> and nullroutes based on them. Your whole /24 is on the SBL:
> https://check.spamhaus.org/results?query=78.153.140.44
> (click on 'more info' at the bottom)

I know, many hosters that allow TOR can land there.

> More info on the MIT behavior here:
> https://gitlab.torproject.org/tpo/network-health/analysis/-/issues/90

Why are directory authorities operated in such networks?
TOR exits are known to become listed on certain IP blacklists/DROP etc.

> and initial analysis about similar UCSD behavior here:
> https://gitlab.torproject.org/tpo/network-health/analysis/-/issues/97
> (You could see whether you can reach SunGod from your relay too.)

I can reach it from both my relays using telnet.

For the traceroute situation, FreeBSD traceroute (different than
traceroute6) I had to pass -e additional to -p 443 and -P tcp.

Now the packet looks like this:

06:24:46.144934 IP teufel.dorfdsl.de.54759 >
sungod.sysnet.ucsd.edu.https: Flags [S], seq 29087207, win 0, length 0

Last hop is 
13  agg-b-mcore.ucsd.edu (132.239.254.44)  197.409 ms  200.302 ms
200.034 ms

I assume traceroute doesn't really implement TCP here, so the packet
will be dropped.

Linux traceroute is different and works.

-- 
kind regards
Marco

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