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The squidGuard FAQ
squidGuard is an ultrafast and free filter, redirector and access
controller for Squid
Originally created by Pål Baltzersen and Lars Erik Håland
Maintained by Christine Kronberg.
Copyright © 2006-2007, Shalla Secure Services
FAQ - Frequently Asked/Answered Questions
This is out of date. Have a look at http://www.maynidea.com/squidguard/faq-plus.html
Currently in semirandom order:
1.
Is there a mailing list for squidGuard?
Yes! See www.shalla.de/mailman/squidguard/.
2.
squidGuard does not block?
There my be at least 2 reasons for this:
1. You didn't end your pass rules with "none". Pass rules
ends with an implicit "all". It is good practice to
allways en the pass rules with either "all" or "none" to
make them clear. Ie. use:
pass good none
or
pass good !bad all
2. squidGuard goes into emergency mode. Reasons may be
syntax errors in the config file, reference to non
existing database files, filprotection problems or
missing directories. Check the squidGuard log.
Note:When run under Squid, squidGuard is run with the
same user and group ID as Squid (cache_effective_user
and cache_effective_group in squid.conf). The squidGuard
configuration and database files must be readable for
this user and/or group and the squidGuard log directory
must be writable for this user and/or group. If not
squidGuard will go into the "pass all for all" emergency
mode.
3.
How do I debug squidGuard?
Do something like this:
echo "http://foo/bar 10.0.0.1/- - GET" | /usr/local/bin/s
quidGuard -c /tmp/test.cfg -d
This redirects the log to stderr. The response is either
a blank line (pass on) or a the input with the URL part
rewritten (redirect).
4.
How can I block audio and video?
Use an [11]expressionlist with something like this:
\.(ra?m|mpe?g?|mov|movie|qt|avi|dif|dvd?|mpv2|mp3)($|\?)
5.
How can I test timeconstraints
You can set a simulated start time with the
-t yyyy-mm-ddTHH:MM:SS option:
squidGuard -c test.conf -t 1999-12-31T23:59:30 -d <
test.in>test.out 2>test.log
With the -t option squidGuard parses the given date&time
and calculates an offset from the current time at startup
and then adds this offset to all timevalues during
runtime.
6.
squidGuard compiles fine and the tests succeed, but it seems to
pass all when run under Squid
There may be at leaste two reasons for this:
o Some versions of Squid (supposedly 2.2.*) silently
ignores argumets to the right of
redirect_program prefix/bin/squidGuard. Solutions are
one of:
# Set the actual config file location at
[13]compiletime with --with-sg-config
# Use a shell wraper with
redirect_program prefix/bin/squidGuard.sh and make
prefix/bin/squidGuard.sh an executable shell like:
#! /bin/sh -
exec prefix/bin/squidGuard -c whatever/
squidGuard.conf
o When run under Squid, squidGuard is run with the same
user and group ID as Squid (cache_effective_user and
cache_effective_group in squid.conf). The squidGuard
configuration and database files must be readable for
this user and/or group and the squidGuard log directory
must be writable for this user and/or group. If not
squidGuard will go into the "pass all for all" emergency
mode.
7.
compilation of sg.l on fails with "sg.l:line ...: Error: Too many
positions" with native lex
Some native versions of lex have problems with sg.l. The
solution is to use [14]GNU flex wich is better anyway. Do
"setenv LEX flex" if configure selects the native lex
before flex. Flex should compile right out of the box
similar to other GNU programs. (Thanks to
laurent.foulonneau@mail.loyalty.nc).
8.
Can I use proxy authenticated user the same way as RFC931/Ident
user?
Yes.
9.
Can I manipulate domains.db and urls.db from Perl?
Yes, but you must bind custom comparefunctions. Also note
the domains are stored with a leading ".":
use DB_File;
sub mirror($) {
scalar(reverse(shift));
}
sub domainmatch($$) {
my $search = mirror(lc(shift));
my $found = mirror(lc(shift));
if ("$search." eq $found) {
return(0);
} else {
return(substr($search,0,length($found)) cmp $found);
}
}
sub urlmatch($$) {
my $search = lc(shift) . "/";
my $found = lc(shift) . "/";
if ($search eq $found) {
return(0);
} else {
return(substr($search,0,length($found)) cmp $found);
}
}
my (%url,%domain);
$DB_BTREE->{compare} = \&urlmatch;
my $url_db = tie(%url, "DB_File", "urls.db", O_CREAT|O_RDWR, 0664, $DB_
BTREE)
|| die("urls.db: $!\n");
$DB_BTREE->{compare} = \&domainmatch;
my $domain_db = tie(%domain, "DB_File", "domains.db", O_CREAT|O_RDWR, 0
664, $DB_BTREE)
|| die("domains.db: $!\n");
# Now you can operate on %url and %domain just as normal perl hashes:)
# Add "playboy.com" to the domainlist unless it's already there:
$domain{".playboy.com"} = "" unless(exists($domain{"playboy.com"}));
# or use the DB_File functions put, get, del and seq:
# Add "sex.com" and "dir.yahoo.com/business_and_economy/companies/sex"
# and delete "cnn.com":
$domain_db->put(".sex.com","") unless(exists($domain{"sex.com"}));
$domain_db->sync; # Seems to only sync the last change.
$domain_db->del("cnn.com") if(exists($domain{"cnn.com"}));
$domain_db->sync; # Seems to only sync the last change.
$url_db->put("xyz.com/~sex","") unless(exists($url{"xyz.com/~sex"}));
$url_db->sync; # Seems to only sync the last change.
$url_db->sync; # Seems to only sync the last change.
$domain_db->sync; # Seems to only sync the last change.
undef($url_db); # Destroy the object
undef($domain_db); # Destroy the object
untie(%url); # Sync and close the file and undef the hash
untie(%domain); # Sync and close the file and undef the hash
See the perltie(1) and DB_File(3) man pages that comes
with Perl for more info.
10.
How can I list domains.db or urls.db from Perl?
Use a script like this:
#!/local/bin/perl -w
use strict;
use DB_File;
foreach (@ARGV) {
my (%db, $key, $val);
die("$_: $!\n") unless(-f);
tie(%db, "DB_File", $_, O_RDONLY, 0664, $DB_BTREE) || die("$_: $!\n")
;
foreach $key (keys(%db)) {
if($val = $db{$key}) {
$val = "\"$val\"";
} else {
$val = "undef";
}
print "$key -> $val\n";
}
untie(%db);
}
See the perltie(1) and DB_File(3) man pages that comes
with Perl for more info.
11.
How can I get around "make: don't know how to make /bin/false.
Stop"?
Your system does not have lynx and not /bin/false either:
If it has /usr/bin/false do:
# ln -s ../usr/bin/false /bin/.
Alternatively:
# echo exit 255 >/bin/false
# chmod a+rx /bin/false
If you have questions and/or answers that should be on the FAQ list
please send them to sg-bugs (at) squidguard.org
____________________________
References
1. http://www.squidguard.org/
2. http://www.squid-cache.org/
4. http://www.squidguard.org/Doc/
5. http://www.gnu.org/
6. http://www.perl.com/
7. http://www.squid-cache.org/