[squid-users] squid and netdata causes squid to drop SYN?

Matus UHLAR - fantomas uhlar at fantomas.sk
Tue Jan 21 09:32:34 UTC 2020

On 21.01.20 09:58, Amish wrote:
>Recently, I started using netdata to monitor various system functions 
>(which also monitors squid)
>I am using squid (v4.9) with transparent (NAT) as well as Proxy mode 
>(on different ports). Network has 10-15 users. Some on transparent 
>proxy (redirection to port 3128) and some via proxy setting (port 
>8080) in browser.
>Netdata calls squidclient every second to fetch squid statistics. (for 
>generating per second graphs / statistics)
>After I started using netdata, everything worked fine for a while. But 
>then many users started complaining that they are not able to access 
>sites. (Sometimes it worked and sometimes not.)
>I could see SYN packets coming in but there were no SYN,ACK going 
>back. I quickly went through cache.log but did not find anything. 
>(searched for descriptors). I believe (but not 100% sure) that this 
>happened only with those on transparent proxy. (again not sure)
>Then I restarted the squid and all was well. But then issue happened 
>again and I disabled netdata's squid module and now all is working 
>fine from few days.
>So I suspect that netdata calling squidclient every second is not a 
>right thing to do. Its probably causing denial-of-service on squid.

very apparently.

>1) Is there any squid setting which I can adjust? (File descriptors 
>available is 16384)
>2) Is calling squidclient so frequently a right thing to do by 
>netdata? Its probably over loading squid. (I will report to netdata if 

I would use snmp for that. You surely don't need every variable available.
netdata seems to support SNMP.

Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
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