Squid https filtering squidguard acl target list - erratic behaviour

frscm · Nov 27, 2021, 4:28 PM

Hi there,

having worked with pfsense for more than 10 years now in a multi sites configuration, we are now facing something that never occured before, which could be described as an erratic behaviour in squid https filtering : some websites specified in squidgard target categories pass through the web filtering, and some don't. It might have started since we upgraded our pfsenses to 2.5.2, but we are not really sure.

We made some investigations using a very simplified pfsense configuration as follows :

fresh install of pfsense 2.5.2 whith only squid and squidguard installed
squid with default configuration, transparent mode and SSL man in the middle filtering activated (with an internal CA created through the certificate manager with default parameters)
squidguard : created a target categorie with two URLs, parisaeroport.fr and visitstrasbourg.fr, and denying this in Common ACL target rules list.

Here is the surprise : parisaeroport.fr is blocked as intended, but visitstrasbourg.fr is not blocked at all, without any clear records in squid logs that could highlight that difference.

We double checked, it is not a cache problem, but we might have missed something in squid configuration ? Any help would be much appreciated!
Thanks a lot in advance.

Here is the squidguard configuration file :

# ============================================================
# SquidGuard configuration file
# This file generated automaticly with SquidGuard configurator
# (C)2006 Serg Dvoriancev
# email: dv_serg@mail.ru
# ============================================================

logdir /var/squidGuard/log
dbhome /var/db/squidGuard

# 
dest target_test {
	domainlist target_test/domains
	log block.log
}

# 
rew safesearch {
	s@(google..*/search?.*q=.*)@&safe=active@i
	s@(google..*/images.*q=.*)@&safe=active@i
	s@(google..*/groups.*q=.*)@&safe=active@i
	s@(google..*/news.*q=.*)@&safe=active@i
	s@(yandex..*/yandsearch?.*text=.*)@&fyandex=1@i
	s@(search.yahoo..*/search.*p=.*)@&vm=r&v=1@i
	s@(search.live..*/.*q=.*)@&adlt=strict@i
	s@(search.msn..*/.*q=.*)@&adlt=strict@i
	s@(.bing..*/.*q=.*)@&adlt=strict@i
	s@(duckduckgo..*/?.*q=.*)@&kp=1@i
	s@(rambler..*/?.*query=.*)@&adult=family@i
	s@(qwant..*/?.*q=.*)@&s=2@i
	s@(ecosia..*/search.*q=.*)@&safesearch=2@i
	s@(onesearch..*/yhs/search.*)@&vm=r@i
	log block.log
}

# 
acl  {
	# 
	default  {
		pass !target_test all
		redirect http://192.168.10.9:80/sgerror.php?url=403%20&a=%a&n=%n&i=%i&s=%s&t=%t&u=%u
		log block.log
	}
}

and the squid configuration :

# This file is automatically generated by pfSense
# Do not edit manually !

http_port 192.168.10.9:3128 ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.2048 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

http_port 127.0.0.1:3128 intercept ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.2048 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

https_port 127.0.0.1:3129 intercept ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.2048 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

icp_port 0
digest_generation off
dns_v4_first off
pid_filename /var/run/squid/squid.pid
cache_effective_user squid
cache_effective_group proxy
error_default_language fr
icon_directory /usr/local/etc/squid/icons
visible_hostname localhost
cache_mgr admin@localhost
access_log /var/squid/logs/access.log
cache_log /var/squid/logs/cache.log
cache_store_log none
netdb_filename /var/squid/logs/netdb.state
pinger_enable on
pinger_program /usr/local/libexec/squid/pinger
sslcrtd_program /usr/local/libexec/squid/security_file_certgen -s /var/squid/lib/ssl_db -M 4MB -b 2048
tls_outgoing_options cafile=/usr/local/share/certs/ca-root-nss.crt
tls_outgoing_options capath=/usr/local/share/certs/
tls_outgoing_options options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE
tls_outgoing_options cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS
sslcrtd_children 5

logfile_rotate 0
debug_options rotate=0
shutdown_lifetime 3 seconds
# Allow local network(s) on interface(s)
acl localnet src  192.168.10.0/24
forwarded_for on
uri_whitespace strip

acl dynamic urlpath_regex cgi-bin ?
cache deny dynamic

cache_mem 64 MB
maximum_object_size_in_memory 256 KB
memory_replacement_policy heap GDSF
cache_replacement_policy heap LFUDA
minimum_object_size 0 KB
maximum_object_size 4 MB
cache_dir ufs /var/squid/cache 100 16 256
offline_mode off
cache_swap_low 90
cache_swap_high 95
cache deny all
# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp:    1440  20%  10080
refresh_pattern ^gopher:  1440  0%  1440
refresh_pattern -i (/cgi-bin/|?) 0  0%  0
refresh_pattern .    0  20%  4320


#Remote proxies


# Setup some default acls
# ACLs all, manager, localhost, and to_localhost are predefined.
acl allsrc src all
acl safeports port 21 70 80 210 280 443 488 563 591 631 777 901  3128 3129 1025-65535 
acl sslports port 443 563  

acl purge method PURGE
acl connect method CONNECT

# Define protocols used for redirects
acl HTTP proto HTTP
acl HTTPS proto HTTPS

# SslBump Peek and Splice
# http://wiki.squid-cache.org/Features/SslPeekAndSplice
# http://wiki.squid-cache.org/ConfigExamples/Intercept/SslBumpExplicit
# Match against the current step during ssl_bump evaluation [fast]
# Never matches and should not be used outside the ssl_bump context.
#
# At each SslBump step, Squid evaluates ssl_bump directives to find
# the next bumping action (e.g., peek or splice). Valid SslBump step
# values and the corresponding ssl_bump evaluation moments are:
#   SslBump1: After getting TCP-level and HTTP CONNECT info.
#   SslBump2: After getting TLS Client Hello info.
#   SslBump3: After getting TLS Server Hello info.
# These ACLs exist even when 'SSL/MITM Mode' is set to 'Custom' so that
# they can be used there for custom configuration.
acl step1 at_step SslBump1
acl step2 at_step SslBump2
acl step3 at_step SslBump3
http_access allow manager localhost

http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access deny !safeports
http_access deny CONNECT !sslports

# Always allow localhost connections
http_access allow localhost

request_body_max_size 0 KB
delay_pools 1
delay_class 1 2
delay_parameters 1 -1/-1 -1/-1
delay_initial_bucket_level 100
delay_access 1 allow allsrc

# Reverse Proxy settings


# Package Integration
url_rewrite_program /usr/local/bin/squidGuard -c /usr/local/etc/squidGuard/squidGuard.conf
url_rewrite_bypass off
url_rewrite_children 16 startup=8 idle=4 concurrency=0

# Custom options before auth


# Set YouTube safesearch restriction
acl youtubedst dstdomain -n www.youtube.com m.youtube.com youtubei.googleapis.com youtube.googleapis.com www.youtube-nocookie.com
request_header_access YouTube-Restrict deny all
request_header_add YouTube-Restrict none youtubedst
ssl_bump peek step1
ssl_bump bump all
# Setup allowed ACLs
# Allow local network(s) on interface(s)
http_access allow localnet
# Default block all to be sure
http_access deny allsrc