[squid-users] Squid doesn't reload webpage like other clients do

[Troiano Alessio]

Hello,
I've squid 3.5.20 running on RHEL 7.4.
I have a problem to access some websites, for example www.nato.int.
This website apply an Anti-DDoS system that reset the first connection after the TCP 3-way handshake (SYN/SYN-ACK/ACK/RST-ACK). All subsequent TCP connections are accepted. The website administrator say's it is by design.
When I browse that site directly with all browser (IE, FF, Chrome) I see the normal site showed. Anyway it is because after the first reset the client try to reload the page. I've the same behaviour also with wget:

[root at soc-pe-nagios01 ~]# wget www.nato.int
--2017-10-30 10:02:50--  http://www.nato.int/
Resolving www.nato.int... 152.152.31.120
Connecting to www.nato.int|152.152.31.120|:80... connected.
HTTP request sent, awaiting response... No data received.
Retrying.

--2017-10-30 10:02:51--  (try: 2)  http://www.nato.int/
Connecting to www.nato.int|152.152.31.120|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://www.nato.int/ [following]
--2017-10-30 10:02:51--  https://www.nato.int/
Connecting to www.nato.int|152.152.31.120|:443... connected.
WARNING: cannot verify www.nato.int's certificate, issued by '/C=BE/O=GlobalSign nv-sa/CN=GlobalSign Organization Validation CA - SHA256 - G2':
  Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: 'index.html.17'

    [      <=>                                                                                         ] 168,229      147K/s   in 1.1s

2017-10-30 10:03:39 (147 KB/s) - index.html.17 saved [168229]

When I browse the site with squid proxy the browser receive an "Empty Response" squid error page (HTTP error code 502 Bad Gateway) and doesn't do the automatic retry:

[root at soc-pe-nagios01 ~]# wget www.nato.int -e use_proxy=yes -e http_proxy=172.31.1.67:8080
--2017-10-30 10:41:09--  http://www.nato.int/
Connecting to 172.31.1.67:8080... connected.
Proxy request sent, awaiting response... 502 Bad Gateway
2017-10-30 10:41:09 ERROR 502: Bad Gateway.

I can't find an RFC that confirm if browser and proxyes should try a page reload, or if squid has an option to do that.

Any help is appreciated.

Best Regards, Alessio.

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