[squid-users] client->Squid: TCP [RST] and [RST,ACK]

[Alex Rousskov]

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

HTH,

Alex.


> wt., 28 lut 2023 o 08:12 Maciej Leks <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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