[squid-users] squid ssl-bump with icap returns 503

[Amos Jeffries]

On 4/03/21 11:36 pm, Niels Hofmans wrote:
> Hi guys,
> 
> I’m asking here but since I’m not too comfortable with a mailing list, 
> it’s also on serverfault.com <http://serverfault.com>: 
> https://serverfault.com/questions/1055663/squid-icap-not-working-if-using-tls-interception-but-both-work-separately 
> <https://serverfault.com/questions/1055663/squid-icap-not-working-if-using-tls-interception-but-both-work-separately>
> 
> I have an odd issue that squid will return a HTTP 503 when I try to do 
> ICAP for an ssl-bumped HTTPS website. HTTP website works fine.
> Any ideas?
> 
> Config:
> 
> visible_hostname proxy
> forwarded_for delete
> via off
> httpd_suppress_version_string on
> logfile_rotate 0
> cache_log stdio:/dev/stdout
> access_log stdio:/dev/stdout
> cache_store_log stdio:/dev/stdout
> dns_v4_first on
> cache_dir ufs /cache 100 16 256
> pid_filename /cache/squid.pid
> mime_table /usr/share/squid/mime.conf
> http_port 0.0.0.0:3128
> https_port 0.0.0.0:3129 \
>      generate-host-certificates=on dynamic_cert_mem_cache_size=10MB \
>      tls-cert=/etc/squid/ssl/squid.crt tls-key=/etc/squid/ssl/squid.key


Neither of these Squid listening ports do SSL-Bump (aka. interception of 
TLS) in any way.

The first receives normal HTTP forward/explicit proxy traffic over TCP.

The second receives normal HTTP forward/explicit proxy traffic over TLS 
(aka "TLS explicit proxy"). Not to be confused with HTTPS (https:// URLs).



> ssl_bump peek all
> ssl_bump bump all
> quick_abort_min 0
> quick_abort_max 0
> quick_abort_pct 95
> pinger_enable off
> icap_enable on
> icap_service_failure_limit -1
> icap_service service_req reqmod_precache bypass=0 
>   icap://10.10.0.119:1344/
> icap_preview_enable on
> adaptation_access service_req allow all
> cache_mem 512 mb
> dns_nameservers 1.1.1.1 1.0.0.1
> cache_effective_user proxy
> sslcrtd_program /usr/lib/squid/security_file_certgen -s /cache/ssl_db -M 4MB
> sslcrtd_children 8 startup=1 idle=1
> sslproxy_cert_error allow all
> http_access allow all
> 
> Log line HTTPS when it doesn’t work:
> 1614853306.542     40 172.17.0.1 NONE/503 0 CONNECT //ironpeak.be:443 
>  - HIER_NONE/- -

This is a https:// request which the client is tunneling (CONNECT) 
through a forward/explicit proxy.


> 
> < HTTP/1.1 503 Service Unavailable
> < Server: squid
> < Mime-Version: 1.0
> < Date: Thu, 04 Mar 2021 10:36:05 GMT
> < Content-Type: text/html;charset=utf-8
> < Content-Length: 1849
> < X-Squid-Error: ERR_DNS_FAIL 0
> 
> 
> Log line HTTP when it does work:
>    -1 1614851916 text/plain 60/60 GET 
> http://ironpeak.be/blog/big-sur-t2rminator/ 


As you can see this is *not* an HTTPS (https://) request. It is a normal 
HTTP (http://) request sent to a proxy over TLS - which is what your 
port 3129 is expecting.


Amos