[squid-users] client->Squid: TCP [RST] and [RST,ACK]
Alex Rousskov
rousskov at measurement-factory.com
Tue Feb 28 19:06:11 UTC 2023
On 2/28/23 13:07, Maciej Leks wrote:
>>Does child Squid bump the TLS client connection, tunnel it, or
>>terminates it (i.e. the child works as a reverse proxy)?
> * client connects to child Squid's http_port without "ssl-bump".
> * client sends a plain text CONNECT request to child Squid.
> * child Squid connects to parent using cache_peer with mTLS.
I assume that, by mTLS, you mean a cache_peer directive with "tls"
option _and_ with "sslcert" (or equivalent) option to specify the TLS
client certificate to be sent to the cache peer.
I assume that the packets you pasted earlier were between a child Squid
and its parent.
>> What are those TLS alerts?
> Code 21 - decryption_failed_RESERVED(21).
I would focus on this error and ignore RST packets for now. Most likely,
this error is what triggers those packets.
HTH,
Alex.
>>If those TLS alerts are close_notify alerts, then the RST packets you
>>are seeing are probably triggered by the other side doing clean TLS
>>shutdown (i.e. sending a TLS close_notify alert before closing the
>>connection), either after receiving a FIN packet (unlikely with
>>half_closed_clients off?) or while that FIN packet is being generated or
>>is in-flight. When Such RST packets would be sent by the TCP stack
>>rather than Squid code itself. They may be an indication of a benign
>>race condition, a bug, or some other deficiency.
>
> half_closed_clients is off
>
>>Higher-level information (who initiates closure and why) may be needed
>>to figure this out. I recommend sharing a link to a compressed ALL,9
>>cache.log reproducing the problem with a single transaction _combined_
>>with a matching packet trace file in libpcap format.
>
> There is no other way than turning debug on.
>
> Maciek
>
> wt., 28 lut 2023 o 15:15 Alex Rousskov <rousskov at measurement-factory.com
> <mailto:rousskov at measurement-factory.com>> napisał(a):
>
> On 2/28/23 08:35, Maciej Leks wrote:
> > Am I right in saying that RST it's a design intent of squid to end
> > connections quickly? I've started digging into the squid code and see
> > SO_LINGER and timeout set to 0, which means that it's done on purpose
> > not to hang on connections in TIME_WAIT state?
>
> Does child Squid bump the TLS client connection, tunnel it, or
> terminates it (i.e. the child works as a reverse proxy)?
>
> What are those TLS alerts?
>
> If those TLS alerts are close_notify alerts, then the RST packets you
> are seeing are probably triggered by the other side doing clean TLS
> shutdown (i.e. sending a TLS close_notify alert before closing the
> connection), either after receiving a FIN packet (unlikely with
> half_closed_clients off?) or while that FIN packet is being
> generated or
> is in-flight. When Such RST packets would be sent by the TCP stack
> rather than Squid code itself. They may be an indication of a benign
> race condition, a bug, or some other deficiency.
>
> Higher-level information (who initiates closure and why) may be needed
> to figure this out. I recommend sharing a link to a compressed ALL,9
> cache.log reproducing the problem with a single transaction _combined_
> with a matching packet trace file in libpcap format.
>
> https://wiki.squid-cache.org/SquidFaq/BugReporting#debugging-a-single-transaction <https://wiki.squid-cache.org/SquidFaq/BugReporting#debugging-a-single-transaction>
>
> HTH,
>
> Alex.
>
>
> > wt., 28 lut 2023 o 08:12 Maciej Leks <maciej.leks at gmail.com
> <mailto:maciej.leks at gmail.com>> napisał(a):
> >>
> >> For a couple of days we've been encountering many ECONNRESET error
> >> messages in our nodejs client to Salesforce. Even if access.log
> shows
> >> only /200 tshark shows a messy communication between client->squid
> >> (child squid).
> >>
> >> The architecture: nodejs client->3..* child squid->2*parent
> >> squids->cloud Salesforce
> >>
> >> Some examples ([RST]]: 46 1.015513576 100.121.10.169 → 100.113.27.73
> >> TCP 66 46098 → 3128 [ACK] Seq=1721 Ack=140135 Win=214656 Len=0
> >> TSval=2672547296 TSecr=1443424287
> >>
> >> 47 1.016152326 100.113.27.73 → 100.121.10.169 TCP 66 3128 →
> 46098
> >> [FIN, ACK] Seq=140135 Ack=1721 Win=42368 Len=0 TSval=1443424288
> >> TSecr=2672547296
> >> 48 1.017856001 100.121.10.169 → 100.113.27.73 TLSv1.2 97
> Encrypted Alert
> >> 49 1.017893411 100.121.10.169 → 100.113.27.73 TCP 66 46098 →
> 3128
> >> [FIN, ACK] Seq=1752 Ack=140136 Win=214656 Len=0 TSval=2672547298
> >> TSecr=1443424288
> >> 50 1.018002285 100.113.27.73 → 100.121.10.169 TCP 54 3128 →
> 46098
> >> [RST] Seq=140136 Win=0 Len=0
> >> 51 1.018019806 100.113.27.73 → 100.121.10.169 TCP 54 3128 →
> 46098
> >> [RST] Seq=140136 Win=0 Len=0
> >>
> >> [RST,ACK]:
> >> 592 67.664585034 100.121.10.169 → 100.113.27.73 TLSv1.2 97
> Encrypted Alert
> >> 593 67.664737552 100.113.27.73 → 100.121.10.169 TCP 66 3128 →
> 52202
> >> [ACK] Seq=7973 Ack=1129 Win=42752 Len=0 TSval=1443490937
> >> TSecr=2672613945
> >> 594 67.664841613 100.121.10.169 → 100.113.27.73 TCP 66 52202
> → 3128
> >> [FIN, ACK] Seq=1129 Ack=7973 Win=42368 Len=0 TSval=2672613945
> >> TSecr=1443490937
> >> 595 67.664895660 100.113.27.73 → 100.121.10.169 TCP 66 3128 →
> 52202
> >> [RST, ACK] Seq=7973 Ack=1129 Win=42752 Len=0 TSval=1443490937
> >> TSecr=2672613945
> >> 596 67.664936264 100.113.27.73 → 100.121.10.169 TCP 54 3128 →
> 52202
> >> [RST] Seq=7973 Win=0 Len=0
> >>
> >> I'm wondering how to debug it (what exactly) and whether the reason
> >> may be on the squid side (specific configuration?).
> >>
> >> env: GKE/k8s
> >> client container: alpine linux
> >> child squid container: alpine linux
> >> version: 5.7
> >>
> >> Cheers,
> >> Maciek Leks
> > _______________________________________________
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