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Re: ext_user ACL

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On 10/02/2012 6:20 a.m., Wladner Klimach wrote:
Amos,

look at this:

ACL::ChecklistMatches: result for 'restrictedDomains' is 1
2012/02/09 15:16:00.498| ACLList::matches: result is true
2012/02/09 15:16:00.498| ACLList::matches: checking restrictUsers
2012/02/09 15:16:00.498| ACL::checklistMatches: checking 'restrictUsers'
2012/02/09 15:16:00.498| ACL::cacheMatchAcl: cache hit on acl
'restrictUsers' (0x7f402fb23e40)
2012/02/09 15:16:00.498| ACL::ChecklistMatches: result for 'restrictUsers' is 1
2012/02/09 15:16:00.498| ACLList::matches: result is true
2012/02/09 15:16:00.498| aclmatchAclList: 0x7f40304547d8 returning
true (AND list satisfied)
2012/02/09 15:16:00.498| ACLChecklist::markFinished: 0x7f40304547d8
checklist processing finished
2012/02/09 15:16:00.498| ACLChecklist::check: 0x7f40304547d8 match
found, calling back with 0
2012/02/09 15:16:00.498| ACLFilledChecklist::checkCallback:
0x7f40304547d8 answer=0
2012/02/09 15:16:00.498| ACLChecklist::checkCallback: 0x7f40304547d8 answer=0
2012/02/09 15:16:00.498| aclIsProxyAuth: called for restrictUsers
2012/02/09 15:16:00.498| ACL::FindByName 'restrictUsers'
2012/02/09 15:16:00.498| aclIsProxyAuth: returning 1
2012/02/09 15:16:00.498| Gadgets.cc(57) aclGetDenyInfoPage: got called
for restrictUsers
2012/02/09 15:16:00.498| aclGetDenyInfoPage: no match


Even though the logs show as squid blocking one page, at the browser I

Re: "What's the problem?"

That only shows Squid matching "deny restrictedDomains restrictUsers" and looking for a page to send in the 407 response created by aclIsProxyAuth. It may be the first of several such sequences, while the browser tries to find some credentials which Squid will accept. Ending in an allowed.

There is not enough to see the browser actually getting the page load. You will need to keep following the trace further to see what was sent back to the browser, and whether that is actually the request which your successful access result came from.

still can access it. Here is my .conf:

auth_param negotiate program
/etc/squid/squid-3.1.16/helpers/negotiate_auth/squid_kerb_auth/squid_kerb_auth
  -s HTTP/trotsky.example.com
auth_param negotiate children 10
auth_param negotiate keep_alive on

# ACLs externas para buscar grupo baseado em Kerberos.
external_acl_type squid_kerb_ldap  ttl=3600 negative_ttl=3600 %LOGIN
/etc/squid/squid-3.1.16/squid_kerb_ldap/squid_kerb_ldap   -S
californio.example.com  -g
Internet@xxxxxxxxxxx
##################
visible_hostname example.com
dns_nameservers  127.0.0.1
append_domain  .camara.gov.br
hierarchy_stoplist cgi-bin ?
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1

follow_x_forwarded_for allow localhost

# Recommended minimum configuration:
#
acl localnet src 10.0.0.0/8     # RFC1918 possible internal network
acl SSL_ports port 443
acl SSL_ports port 1863
acl SSL_ports port 563
acl SSL_ports port 465
acl SSL_ports port 995
acl Safe_ports port 80          # http
acl Safe_ports port 21          # ftp
acl Safe_ports port 443         # https
acl Safe_ports port 563         # https
acl Safe_ports port 465         # https
acl Safe_ports port 995         # https
acl Safe_ports port 70          # gopher
acl Safe_ports port 210         # wais
acl Safe_ports port 1025-65535  # unregistered ports
acl Safe_ports port 280         # http-mgmt
acl Safe_ports port 488         # gss-http
acl Safe_ports port 591         # filemaker
acl Safe_ports port 777         # multiling http
acl CONNECT method CONNECT
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY

# Recommended minimum Access Permission configuration:
#
acl AUTENTICADO proxy_auth REQUIRED
# Only allow cachemgr access from localhost
acl ldap_group_check external squid_kerb_ldap
acl Maquinas_Portaria src  "/etc/squid/Maquinas_Portaria.txt"
acl Horario_Portaria time MTWHF 7:00-20:00
http_access deny Maquinas_Portaria Horario_Portaria
acl Horario_youtube time TWH 9:00-20:00
acl bloqueio-youtube dstdomain  www.youtube.com
http_access deny bloqueio-youtube Horario_youtube
acl restrictUsers  proxy_auth P_7501@xxxxxxxxxxx
acl restrictedDomains url_regex -i "/etc/squid/InstantMessenger"
http_access deny restrictedDomains restrictUsers

Denies if the user *is* logged in. Okay as an idea, but if the user is NOT logged in it will request credentials until one of the restrictUsers set is given. You can stick " all" at the end of that access line to skip challenging for credentials for other users and not logged in users.

http_access allow ldap_group_check

Unlimited access to anyone in the group unless they are visiting youtube, using Instant Messager, or one of the Maquinas_Portaria machines.

This has a big security holes. These people are allowed management access to your proxy, access unsafe ports, and to relay traffic through your proxy with CONNECT tunnels whenever they please. Notice how they can use CONNECT to a proxy outside your network to get access to Youtube and use Instant Messager despite your controls. This is why the CONNECT security rule is recommended to be above your users allow rules.

#http_access allow AUTENTICADO
#http_access allow localnet
http_access allow manager localhost
http_access deny manager
http_access deny !Safe_ports
http_access deny to_localhost

http_access allow CONNECT SSL_Ports

This is also a broken inversion of the security protections. It permits CONNECT tunnels to be made to anywhere if it was a port in SSL_Ports. The whole idea of the default security is to block non-SSL ports, not to permit unlimited access to SSL ports. Thus the particular form of:

    http_access deny CONNECT !SSL_Ports

... and also why it is recommended to be above any other allow rules for your clients.

The set starting from "allow manager localhost" down to "deny to_localhost" are similar protections, also recommended to be run first before any client allow rules.

http_access deny all


What's the problem?

Regards,

Wladner


Amos


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