[squid-users] Help to understand tcp_denied in access.log

[Alex Rousskov]

On 4/13/23 21:23, andre.bolinhas at articatech.com wrote:

> I'm seeing to many requests to website mainnet.infura.io, by analyzing the
> access.log seams that the website is blocked 

Which directive/mechanism blocks them (e.g., http_access, 
reply_body_max_size, ICAP/eCAP, etc.)?


> Each TCP_DENIED request is consuming 400000+ bytes 

Assuming you do not use huge custom TCP_DENIED error pages, I agree that 
these entries look suspicious, as if Squid denied access but continued 
to tunnel the traffic. The response times are fairly small, but probably 
large enough to transmit those amounts of data from a fast server.

Since most requests (for the affected domain) are problematic, can you 
collect a packet trace and see if you can confirm that these 
transactions transmit a lot of data from Squid to the client? If IPs are 
not enough, logging client TCP port (%>p) may help you match specific 
access.log entries with TCP connections in the packet trace...


What Squid version are you using for this? Does SslBump affect the 
problematic transactions?


Thank you,

Alex.



> but I also notice that the
> request is consuming bandwidth, here a example
> Squid access.log format.
> %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a:%<p %mt mac="%>eui"
> %note ua="%{User-Agent}>h" exterr="%err_code|%err_detail"
> 
> Access.log request.
> 1681099742.517     35 10.81.216.114 TCP_DENIED_ABORTED/407 41154 CONNECT
> mainnet.infura.io:443 - HIER_NONE/-:- text/html mac="00:00:00:00:00:00"
> category:%20143%0D%0Acategory-name:%20Trackers%0D%0Aclog:%20cinfo:143-Tracke
> rs;%0D%0A ua="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)
> AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36"
> exterr="ERR_CACHE_ACCESS_DENIED|-"
> 
> 1681099742.575     41 10.81.216.114 TCP_DENIED/407 511819 CONNECT
> mainnet.infura.io:443 - HIER_NONE/-:- text/html mac="00:00:00:00:00:00"
> category:%20143%0D%0Acategory-name:%20Trackers%0D%0Aclog:%20cinfo:143-Tracke
> rs;%0D%0A ua="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)
> AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36"
> exterr="ERR_CACHE_ACCESS_DENIED|-"
> 
> 1681099742.664     73 10.81.216.114 NONE/200 0 CONNECT mainnet.infura.io:443
> HLBHO/tsyafiq HIER_NONE/-:- - mac="00:00:00:00:00:00"
> category:%20143%0D%0Acategory-name:%20Trackers%0D%0Aclog:%20cinfo:143-Tracke
> rs;%0D%0Auser:%20HLBHO/tsyafiq%0D%0A ua="Mozilla/5.0 (Macintosh; Intel Mac
> OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0
> Safari/537.36" exterr="-|-"
> 
> 1681099742.685     20 10.81.216.114 TCP_DENIED_ABORTED/403 450655 CONNECT
> mainnet.infura.io:443 HLBHO/tsyafiq HIER_NONE/-:- text/html
> mac="00:00:00:00:00:00"
> category:%20143%0D%0Acategory-name:%20Trackers%0D%0Aclog:%20cinfo:143-Tracke
> rs;%0D%0Auser:%20HLBHO/tsyafiq%0D%0A ua="-" exterr="ERR_ACCESS_DENIED|-"
> 
> Each TCP_DENIED request is consuming 400000+ bytes so at the end of the day
> sometimes I have a total of 56k request to mainnet.infura.io consuming
> around 15GB of bandwidth.
> 
> My question is, assuming that %<st is the total size of reply, why
> TCP_DENIED is taking a lot of bandwidth to block a website?
> 
> Best regards
> 
> 
> 
> 
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