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forward all requests to another proxy

In my squid.conf I put the same lines that the FAQ recomend, but when I put in
my browser the name of the server squid, I can connect to the Web.

 My squid.conf:

 visible_hostname professor

 cache_log /var/log/squid/cache.log
 cache_access_log /var/log/squid/access.log
 cache_mem 8 MB

 http_port 8080
 icp_port 0
  cache_peer server parent 8080 0 no-query no-digest default
  acl all src
  never_direct allow all

 http_access allow all



"Squid FAQ 4.9 How do I configure Squid forward all requests to another

 For your convienience -

"First, you need to give Squid a parent cache. Second, you need to tell
Squid it can not connect directly to origin servers. This is done with
three configuration file lines:

        cache_peer parent 3128 0 no-query default
        acl all src
        never_direct allow all

Note, with this configuration, if the parent cache fails or becomes
unreachable, then every request will result in an error message."

 My config file has

        cache_peer parent 8118 0 no-query default
        acl all src
        never_direct allow all

in it but I don't think it is working. What is wrong with this configuration?

 My setup will eventually be:-

Browser -> Squid:3128 -> Privoxy:8118 -> ssh -D 8080

 I can test each link one at a time but I'm not sure how to test all of
them at once.

Offtopic but for interest:
 The socks section of my config file is
"forward-socks4 / ."

 I noticed someone else raised this before but I don't think the
forwarding is working for me - when I set my browser proxy to squid on and go to the privoxy test page ( it
says that "Privoxy is not running".

 How can I tell if Squid is the problem or Privoxy?

How do I configure Squid forward all requests to another proxy?

First, you need to give Squid a parent cache. Second, you need to tell Squid it can not connect directly to origin servers. This is done with three configuration file lines:


cache_peer parent 3128 0 no-query default
acl all src
never_direct allow all

Note, with this configuration, if the parent cache fails or becomes unreachable, then every request will result in an error message.

In case you want to be able to use direct connections when all the parents go down you should use a different approach:


cache_peer parent 3128 0 no-query
prefer_direct off

The default behaviour of Squid in the absence of positive ICP, HTCP, etc replies is to connect to the origin server instead of using parents. The prefer_direct off directive tells Squid to try parents first.


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Squid - Autenticazione utenti su dominio Active directory o NT4

E' possibile configurare Squid per autenticare gli utenti che possono usare il proxy usando le credenziali di un dominio Active Directory o di tipo NT4.

L'autenticazione si basa su winbind, il demone fornito con Samba che permette l'autenticazione degli utenti locali di una macchina Linux su un domain controller di un dominio di tipo Active Directory o NT4.

Il servizio winbind deve essere in esecuzione (anche non configurato) e la macchina su cui gira Squid deve aver joinato il dominio.

In <code>/etc/squid/squid.conf</code> devono essere presenti le seguenti configurazioni:

Settaggi relativi al sistema di autenticazione:
<code>auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-basic</code>

Alternativa che negozia automaticamente la password dell'utente loggato sul dominio
<code>auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol= squid-2.5-ntlmssp</code>

Se si vuole permettere accesso solo a utenti del gruppo "navigatori" del dominio "DOMINIO" usare invece questa alternativa:
<code>auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --require-membership-of="DOMINIO+navigatori"</code>
Notare che necessario avere "<code>winbind separator = +</code>" in smb.conf (il file di configurazione di Samba) se si lascia il separator normale \ non funziona!

Le seguenti righe devono essere invece sempre presenti:
<code>auth_param ntlm children 5
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes
auth_param ntlm use_ntlm_negotiate on</code>

E' poi necessario configurare le acl di Squid per forzare la richiesta di autenticazione (cambiare gli ip della local_network secondo le proprie esigenze):
<code>acl password proxy_auth REQUIRED
acl local_network src <var></var>
http_access allow local_network password</code>




verificare i permessidi /var/run/samba/winbindd_privileged

possibile errore:

failed due to [winbind client not authorized to use winbindd_pam_auth_crap. Ensure permissions on /var/run/samba/winbindd_privileged are s
et correctly.]

The correct permissions are to allow *group* access to the privileged
pipe, say to the squid group.

chgrp squid /var/db/samba/winbindd_privileged
chmod g+rx /var/db/samba/winbindd_privileged

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Proxy servers are fairly essential devices that should be part of a network’s perimeter defense strategy. They are devices that allow clients to indirectly access network services via a connection through them. In an enterprise environment, proxy servers are used to aid in enforcement of acceptable use and security policies.

There are a number of reasons for using a proxy server as part of securing a network but that is beyond the scope of this document.

The 10 Legged Creature.

One of the premier proxy servers available today is Squid. It is the most popular HTTP proxy available today, mainly because it is offers a comprehensive set of features, is highly configurable all while being open source and free. It runs on just about any Linux distribution and scales better than any other application of its kind.

For the sake of this exercise, Squid is being deployed to an enterprise network to act in the capacity of a web proxy. By doing so, Squid will be an intermediary for all web browsing between network users and the destinations web sites they desire to browse. When a user requests to visit a site that request will go first to Squid, which will then establish a connection with the destination, transfer the data from the web site to its cache and then pass that data back to the requesting user.

In many instances Squid will even pass the data from its local cache back to the users, both saving time and precious bandwidth. Depending on which algorithm is selected when configuring Squid will determine how Squid decides whether or not to serve the local cache to a user or whether to fetch new data.

Mayday, Mayday!

When I set out to install Squid so that it could perform active directory authentication I was unable to locate any single resource that could explain, in detail, the steps required in order to make this happen. What I did find, however, was a variety of instructions related to various aspects of the entire process. The sum of all the information that I discovered is contained in this document, which will hopefully serve as a means of helping someone else achieve the same goal I was aiming for.

The following are the instructions for installing Squid Proxy Server so that it performs Active Directory authentication off of a Windows 2003 domain controller. Squid is configured so that the browsers must explicitly point to it, which means that it is not being setup to function as a transparent proxy. This entire design was performed on a Dell 1650 running Gentoo Linux 2006.0.

Although the act of downloading, compiling and installing applications on a Gentoo box is slightly different than that of an RPM based distribution (like Red Hat) the same basic configuration directions are applicable. The key difference is Gentoo’s USE flag convention whereas the other distributions will force the use of compile time options (i.e. using “with-winbind” when running configure, as an example).

The following software is necessary in order to make all of this work as planned.

Installation of this software on Gentoo is rather easy however there is a USE flag caveat. In order to ensure that the software is compiled with the necessary options to make this all work properly specific Gentoo USE flags need to be set. This can be done on the command-line while emerging the software or by modifying the make.conf file. Whichever method is selected, the following USE flags need to be set:

<code>USE="kerberos ldap pam"</code>

Using the command-line, emerge the software as follows:

<code>USE="kerberos ldap pam" emerge squid samba openldap mit-krb5</code>

If make.conf was updated to reflect the necessary USE flags then do the following:

<code>emerge squid samba openldap mit-krb5</code>

Once emerge is done working the lovely magic it performs it will be time to modify the various configuration files.


This is only the applicable portion of the squid.conf file required for active directory authentication. In the event that a complete squid.conf file is necessary then take a look here.

# Active Directory configuration
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
auth_param ntlm use_ntlm_negotiate on
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 Server
auth_param basic credentialsttl 2 hours
# Only allow authenticated users to use the proxy
# Add these in the appropriate places in squid.conf
acl authenticated_users proxy_auth REQUIRED
http_access allow authenticated_users</code>


netbios name = proxyserver
realm = DOMAIN.COM
workgroup = DOMAIN
security = ADS
password server =
socket options = TCP_NODELAY SO_RCVBUF=16384 SO_SNDBUF=16384
idmap uid = 10000-20000
winbind enum users = yes
winbind uid = 10000-20000
winbind gid = 10000-20000
winbind separator = +
winbind use default domain = yes
encrypt passwords = yes
log level = 3 passdb:5 auth:10 winbind:5


        ticket_lifetime = 600
        default_realm = DOMAIN.COM
        default_tkt_enctypes = des3-hmac-sha1 des-cbc-crc
        default_tgs_enctypes = des3-hmac-sha1 des-cbc-crc
        dns_lookup_realm = false
        dns_lookup_kdc = false
        DOMAIN.COM = {
                kdc =
                kdc =
                kdc =
                admin_server =
                default_domain = DOMAIN.COM
[domain_realm] = =
        profile = /etc/krb5kdc/kdc.conf
        kdc = FILE:/var/log/krb5kdc.log
        admin_server = FILE:/var/log/kadmin.log
        default = FILE:/var/log/krb5lib.log


auth    required
auth    required service=system-auth-winbind
account  required service=system-auth-winbind
session  required service=system-auth-winbind
password  required service=system-auth-winbind
auth    required  /lib/security/ service=system-auth-winbind
account  required  /lib/security/ service=system-auth-winbind
auth    required
auth    sufficient likeauth nullok
auth    required
account  required
password  required difok=2 minlen=8 dcredit=2 ocredit=2 retry=3
password  sufficient nullok md5 shadow use_authtok
password  required
session  required
session  required</code>

Once all the aforementioned software has been configured as depicted the proxy server needs to be added to the Windows 2003 domain. This is necessary so that the proxy server can perform authentication in conjunction with a Windows 2003 active directory domain controller.

To join the Linux machine to a Windows 2003 domain perform the following:

<code>sudo net ads join Servers/Linux -U AdminAcct -S</code>

If everything went as planned then a message will be echoed on the screen depicting as such. After a few moments, once the domain controllers replicate, the proxy server should show up in the OU that was specified when joining the domain. In the example above, the Linux server would show up in the Linux OU, under the Servers OU in the Windows 2003 domain named

In the event that an error occurred while joining the domain check syslog for possible errors.

At this point, start SAMBA and winbindd by performing the following:

<code>/etc/init.d/samba start

Both of these are necessary in order for Squid to be able to properly perform active directory based authentication. Ensure that winbindd is functioning properly by issuing the following command. If all goes as planned then the following will be the response:

<code>proxyserver ~ # wbinfo –t
checking the trust secret via RPC calls succeeded</code>

Ensure that Squid is able to properly perform active directory authentication by testing the helper application:

<code>/usr/bin/ntlm_auth --helper-protocol=squid-2.5-basic
DOMAIN+username password
  NT_STATUS_OK: Success (00)</code>

Assuming that everything has gone as listed above, start up Squid by issuing the following:

<code>/etc/init.d/squid start</code>

Configure a web browser, such as Firefox or Internet Explorer, to point directly to the proxy server and ensure that browsing is possible without ever being offered an authentication dialogue box. This is testing to ensure that NTLM authentication with the Windows 2003 active directory domain controller is working properly. Confirm that traffic is being properly authorized by tailing the Squid access log file.

<code>tail –f /var/log/squid/access.log
1147739650.906   9969 TCP_MISS/200 4244 CONNECT DOMAIN+username DIRECT/ -
1147739672.965   1085 TCP_REFRESH_MISS/200 2321 GET DOMAIN+username DIRECT/ text/html
1147739673.871    907 TCP_MISS/200 3027 GET DOMAIN+username DIRECT/ image/jpeg
1147739683.229      0 TCP_DENIED/407 1745 CONNECT - NONE/- text/html
1147739683.243      0 TCP_DENIED/407 1874 CONNECT - NONE/- text/html
1147739693.881  10636 TCP_MISS/200 4340 CONNECT DOMAIN+username DIRECT/ -</code>

When using NTLM authentication it is normal to see two simultaneous TCP_DENIED/407 errors. This is due to the nature of the challenge/response mechanism of NTLM authentication.

In the event that no username appear in the squid access log, or password dialogue boxes appear, then check the squid.conf file to ensure that the ACL’s are setup properly. Also ensure that winbindd is functioning, as depicted above. If changes are made to the squid.conf file then squid needs to be restarted in order for those modifications to take affect.

If everything is working as planned then ensure that Squid and SAMBA start automatically upon reboot by issuing the following:

<code>rc-update add squid default
rc-update add samba default</code>

Modify the following file so that winbindd is started after a reboot:

# Start the winbind daemon so we can do AD lookups in Squid

Squid is now properly configured to perform Windows 2003 active directory authentication. Enjoy the added security benefit that a proxy server solution offers, especially since it can perform authentication.

The following resources were used in both the configuring of Squid with active directory authentication, as well as putting this document together:


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squid + websense 6.3.2 squid plug-in (centos 4.7)

quick procedure (more complete instructions here)


tar xfvz WebSecurity632_Setup_Lnx_it.tar.gz

Follow the linked instructions then if you restart squid it will not works!!
if you check for errors you'll see in /var/log/messages

Oct 30 14:58:26 itb-s0039 (squid): The redirector helpers are crashing too rapidly, need help!
Oct 30 14:58:26 itb-s0039 squid[25808]: Squid Parent: child process 25889 exited due to signal 6
Oct 30 14:58:29 itb-s0039 squid[25808]: Squid Parent: child process 25927 started
Oct 30 14:58:29 itb-s0039 (squid): The redirector helpers are crashing too rapidly, need help!
Oct 30 14:58:29 itb-s0039 squid[25808]: Squid Parent: child process 25927 exited due to signal 6
Oct 30 14:58:32 itb-s0039 squid[25808]: Squid Parent: child process 25965 started
Oct 30 14:58:33 itb-s0039 (squid): The redirector helpers are crashing too rapidly, need help!
Oct 30 14:58:33 itb-s0039 squid[25808]: Squid Parent: child process 25965 exited due to signal 6
Oct 30 14:58:33 itb-s0039 squid[25808]: Exiting due to repeated, frequent failures

if you try to start the websense redirector you'll get this error:

./WsRedtor: error while loading shared libraries: cannot open shared object file: No such file or directory


create a new file
vim /etc/


ldconfig -v | grep -i sense
/etc/init.d/squid start

if everything is ok in /var/log/messages you'll only this:

Oct 30 15:11:25 itb-s0039 squid[26062]: Squid Parent: child process 26065 started


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