Squid NTLM authentication configuration using ntlm_auth

by on January 24, 2007 · 16 comments· LAST UPDATED September 12, 2007

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Q. How do I configure squid for NTLM authentication?

A. You need to use squid ntlm_auth helper tool. It o allow external access to Winbind's NTLM authentication function. ntlm_auth uses winbind to access the user and authentication data for a domain.

Make sure winbindd is working

winbindd is a daemon that provides a number of services to the Name Service Switch capability found in most modern C libraries, to arbitary applications via PAM and ntlm_auth and to Samba itself. If you are not sure about winbindd, refer to official Samba documentation for configuration.

Configure squid for NTLM authentication

Open squid configuration file - squid.conf, enter:
# vi squid.conf
Append following configuration directive:
auth_param ntlm program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param basic program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-basic
auth_param basic children 5
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 2 hours

To setup ntlm_auth for use by squid 2.5 with group limitation, add:
auth_param ntlm program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --require-membership-of="WORKGROUP\Domain Users"
auth_param basic program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-basic --require-membership-of="WORKGROUP\Domain Users"
auth_param ntlm children 5
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes

OR You can also pass DOMAIN/PDC name:
auth_param ntlm program /usr/lib/squid/ntlm_auth DOMAINNAME/PDC
auth_param ntlm children 5
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes

Now add ACL configuration for ntlm_auth helper
acl ntlm_users proxy_auth REQUIRED
http_access allow ntlm_users
http_access deny all

Save and close the file. Restart Squid:
# /etc/init.d/squid restart
For more information:

Updated for accuracy.

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{ 16 comments… read them below or add one }

1 Tapan Shah April 9, 2007 at 9:30 am

I am getting an error while configuring this the error is

FATAL: authparam basic program /usr/bin/ntml_auth: (2) No such file or directory
Squid Cache (Version 2.5.STABLE6): Terminated abnormally.
CPU Usage: 0.007 seconds = 0.002 user + 0.005 sys
Maximum Resident Size: 0 KB
Page faults with physical i/o: 0
Aborted. so do reply me about this
Thank you.


2 nixCraft April 11, 2007 at 6:20 pm

Set correct path for /usr/lib/squid/ntml_auth file


3 jayaram July 27, 2007 at 11:09 am

How can l block one Active directory user to access internet through squid ( or blank password users)


4 dark_harmonics September 11, 2007 at 12:32 am

If you are getting error its because the author messed up his script. Check for where he substitues ntml instead of ntlm. Fix that and you are good to go!


5 nixCraft September 12, 2007 at 5:01 am


The FAQ has been updated. I appreciate your feedback.


6 deepak ray September 20, 2007 at 6:28 am

Good work
and we have to share our experiences and idea

to all Linux worker


7 samerk October 25, 2007 at 1:35 pm

thank you guys for this documentation it’s quite helpful when configuring Squid with NTLM.
However i have a couple of questions regarding clients that are not joined to the Active directory DC:

1- a NON-joined client using IE will have to log on using realm/username and passwd. Is there a way to make him authenticate with only his username and passwd ?
NB:It works fine with other browsers such as Firefox.

2- If you use IE with this NTLM auth (on an NON-joined pc) and select the ’save password’ checkbox the password gets stored in the registry as if it was for a network location. To delete the record you will have to run
“rundll32.exe keymgr.dll, KRShowKeyMgr”
This is causing real problems to users. Have you encountered this? and were you able to figure a way out?

Thanks again,


8 newbie June 11, 2008 at 1:15 pm

i have two groups one group has only access to whitelist and another group have full access to internet. how can i setup squid to autorizate groups


9 matu August 13, 2008 at 1:11 pm

For squid 2.6, see the following Wiki page.
I was able to start squid only after configuring squid.conf as described there.


10 matu August 13, 2008 at 1:30 pm

one more thing, on the above wiki page there is a ownership fix by using “cache_effective_group root” in squid,conf. It worked for me only after removing this line from squid.conf. so do not add it to squid.conf.


11 James Johnston October 30, 2008 at 4:54 am

To deal with winbind permissions problems:
(1) add proxy user to winbindd_priv group. (2) comment the “cache_effective_group” line in squid.conf so that secondary groups for the proxy user aren’t ignored.

Once I did that NTLM worked fine.


12 sameer kale April 5, 2009 at 8:22 am

I want to authenticate the user by his username , password and MAC address.. Is it possible by ntlm_auth??? How?


13 bala May 31, 2009 at 8:42 am

Hi I am able to configure NTLM with squid.It works great.
But i use Dansguardian for content filtering.With this setup (DG+SQUID+NTLM) ,things works fine for a user logged in to the domain.But for a local user it does not fall back to the basic program and i get a access denied page (as unauthenticated user fall to filter group 1 in DG)
Any help


14 Avinash.Rao August 18, 2009 at 2:49 pm

Hi all,
Ubuntu 8.04 Server 64-bit Edition/Samba 3.0.28a/Squid 2.6 stable18
Samba is configured as PDC and i have winxp clients logging to the domain. I want to restrict these users from accessing the internet the whole day, i just want to give them access to internet only during 6:00-8:00PM everyday. How can i achieve this?

I read the documentation and have configured squid for NTLM and tested.. but below is the error i am getting when i restart squid.

/etc/init.d/squid restart
* Restarting Squid HTTP proxy squid
2009/08/18 14:04:15| Invalid Proxy Auth ACL ‘acl
AuthorizedUsers proxy_auth REQUIRED’ because no authentication schemes
are fully configured.
FATAL: Bungled squid.conf line 39: acl AuthorizedUsers proxy_auth REQUIRED
Squid Cache (Version 2.6.STABLE1: Terminated abnormally.

visible_hostname sunbox
hierarchy_stoplist cgi-bin ?
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY
hosts_file /etc/hosts
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern . 0 20% 4320
acl all src
acl manager proto cache_object
acl localhost src
acl to_localhost dst
acl SSL_ports port 443 563
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 563 # https, snews
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 631 # cups
acl Safe_ports port 777 # multiling http
acl Safe_ports port 901 # SWAT
acl Safe_ports port 993 # IMAP
acl Safe_ports port 587 # SMTP
acl Safe_ports port 22 # SSH
acl purge method PURGE
acl special_urls url_regex “/etc/squid/squid-noblock.acl”
acl extndeny url_regex -i “/etc/squid/blocks.files.acl”
acl malware_block_list url_regex -i “/etc/squid/malware_block_list.txt”
acl badurl url_regex -i teen orkut youtube sex mp3 mp4 exe
acl lan src
acl stud ident_regex babu
acl download method GET
acl AuthorizedUsers proxy_auth REQUIRED
cache_mem 100 MB
#redirect_program /usr/bin/squidGuard –c /etc/squid/squidGuard.conf
ident_lookup_access allow all
http_access deny all
http_access allow manager localhost
http_access deny manager
http_access allow purge localhost
http_access allow special_urls
http_access deny extndeny download
http_access deny extndeny
http_access deny purge
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access deny badurl
http_access deny malware_block_list
deny_info http://malware.hiperlinks.com.br/denied.shtml malware_block_list
http_access allow localhost
http_access allow lan
http_reply_access allow all
http_access allow AuthorizedUsers
http_access deny all
icp_access allow all
coredump_dir /var/spool/squid

auth_param ntlm program /usr/bin/ntlm_auth –helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 30
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes
# ntlm_auth from Samba 3 supports NTLM NEGOTIATE packet
auth_param ntlm use_ntlm_negotiate on

# warning: basic authentication sends passwords plaintext
# a network sniffer can and will discover passwords
auth_param basic program /usr/bin/ntlm_auth –helper-protocol=squid-2.5-basic
auth_param basic children 5
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 2 hours


15 Chris August 28, 2009 at 6:01 pm

Does anyone know if I will break this if I disable LM on my domain controllers and also possible NTLM v1 so that NTLM V2 is the only thing on my network?We’ve had ntlm_auth running successfully on our network for 8-10 years and love it. But we need to ditch LM and probably NTLM v1. Thanks,


16 Anonymous June 16, 2010 at 6:25 pm

Changing “WORKGROUP\Domain Users” to “workgroup+domain users” worked for me in line below:

auth_param ntlm program /usr/lib/squid/ntlm_auth –helper-protocol=squid-2.5-ntlmssp –require-membership-of=”WORKGROUP\Domain Users”

auth_param basic program /usr/lib/squid/ntlm_auth –helper-protocol=squid-2.5-basic –require-membership-of=”WORKGROUP\Domain Users”


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