Tag: NTLM

IT

Squid with active directory authentication on Centos 6.0

In this post, I'll be writing down all steps required to build a Squid proxy server on a clean "minimal" installation of CentOS 6.0

Step 1. Network configuration

First, install system-config-network or manually configure the network. I prefer system-config-network for easy configurations and vim for more complex configurations.
yum -y install system-config-network-tui

Step 2. Install some tools for convenience

yum -y install vim-minimal vim-enhanced openssh-clients mc telnet policycoreutils policycoreutils-python bind-utils

Step 3. Install ntp and synchronize clocks

If one of the clocks it out of sync, NTLM authentication will not work. Therefore, we synchronize the clocks. Using pool.ntp.org as a source would be good, but if the AD server isn't synchronized with that source, we'd have the same problem. So I'm synchonizing the proxy to the AD server (Win2003SBS actually) instead:
rpm -q ntp || yum -y install ntp
sed -i "s/^server /#server /g" /etc/ntp.conf
echo "server AD-SERVERNAME" >> /etc/ntp.conf
ntpdate AD-SERVERNAME #synchronize right now
service ntpd start #and keep in sync
chkconfig ntpd on

Step 4. Install squid and other required software

yum -y install krb5-workstation samba-common samba-winbind authconfig squid
chkconfig squid on

Step 5. Connect to active directory

Please note that MYCOMPANY.local and mycompany.local may be different domains due to the upper/lowercase.
ADSERVER=sbs.MYCOMPANY.local
DOMAIN=MYCOMPANY.local
WORKGROUP=MYCOMPANY
authconfig --enableshadow --enablemd5 --passalgo=md5 --krb5kdc=$ADSERVER \
--krb5realm=$DOMAIN --smbservers=$ADSERVER --smbworkgroup=$WORKGROUP \
--enablewinbind --enablewinbindauth --smbsecurity=ads --smbrealm=$DOMAIN \
--smbidmapuid="16777216-33554431" --smbidmapgid="16777216-33554431" --winbindseparator="+" \
--winbindtemplateshell="/bin/false" --enablewinbindusedefaultdomain --disablewinbindoffline \
--winbindjoin=Administrator --disablewins --disablecache --enablelocauthorize --updateall
service winbind restart
chkconfig winbind on

Give squid permissions to use winbind info:
usermod -G wbpriv squid

Now check your winbind connection using the following commands:
wbinfo -u
wbinfo -g

Step 6. Firewall

iptables -I INPUT -m tcp -p tcp --dport 3128 -j ACCEPT
/sbin/service iptables save

Step 7. Configure squid

I commented out this line from /etc/squid/squid.conf:
http_access allow localnet
That line would have allowed users from 10.0.0.0/8+172.16.0.0/12+192.168.0.0/16 and others to use the proxy without authentication. Then I added the following right below that line:
acl whitelist dstdom_regex -i "/etc/squid/whitelist"
http_access allow whitelist
auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 5
auth_param ntlm keep_alive on
acl our_networks src 192.168.0.0/16
acl ntlm proxy_auth REQUIRED
http_access allow our_networks ntlm
authenticate_ip_ttl 900 seconds

This will allow all valid, logged in users to surf the web. You could also limit which users can surf by adding --require-membership-of=ADGROUPNAME to the ntlm_auth command

The first two lines of above configuration point to a file /etc/squid/whitelist. This file contains domains that should never be denied. My whitelist file contains:
\.trendmicro\.com
^trendmicro\.com
\.microsoft\.com
^microsoft\.com
This means that anything at *.microsoft.com and microsoft.com (without subdomain) as well as *.trendmicro.com as trendmicro.com (my virusscanner) is always allowed for any user. We wouldn't want to block important updates.

Start Squid using /sbin/service squid restart and the proxy is ready.

Step 8. Optional: IPv6 issues

I've been experimenting with IPv6 for a while now, but I don't have IPv6 available on all systems. That caused me some trouble with the next step. I had to give preference to IPv4 above IPv6 by editting /etc/gai.conf:
label ::1/128 0
label ::/0 1
label 2002::/16 2
label ::/96 3
label ::ffff:0:0/96 4
label fec0::/10 5
label fc00::/7 6
precedence ::ffff:0:0/96 100
precedence ::1/128 50
precedence ::/0 40
precedence 2002::/16 30
precedence ::/96 20

Step 9. Optional: Some white- and blacklisting

We may not want to allow all sites to be visited. For instance, porn sites are often blocked in office situations. I've got a manual on blacklisting using SquidGuard as well.

© GeekLabInfo Squid with active directory authentication on Centos 6.0 is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Install mod_auth_ntlm_winbind on CentOS 6.0

Step 1. Install ntp and synchronize clocks

We'll be using winbind, kerberos and ntlm to authenticate the user. This requires the clocks of the AD server and the proxy server to be synchronized.

yum -y install ntp

sed -i "s/^server /#server /g" /etc/ntp.conf

echo "server YOURSERVERNAME" >> /etc/ntp.conf

ntpdate YOURSERVERNAME #synchronize right now

service ntpd start #and keep in sync

chkconfig ntpd on #after reboot as well

Step 2. Update system and install required software

yum update
yum install mc vim httpd php svn httpd-devel make autoconf gcc ntp krb5-workstation \
samba-common authconfig samba-winbind

Step 3. Connect to active directory

Please note that MYCOMPANY.local and mycompany.local may be different domains due to the upper/lowercase.
ADSERVER=sbs.MYCOMPANY.local
DOMAIN=MYCOMPANY.local
WORKGROUP=MYCOMPANY
authconfig --enableshadow --enablemd5 --passalgo=md5 --krb5kdc=$ADSERVER \
--krb5realm=$DOMAIN --smbservers=$ADSERVER --smbworkgroup=$WORKGROUP \
--enablewinbind --enablewinbindauth --smbsecurity=ads --smbrealm=$DOMAIN \
--smbidmapuid="16777216-33554431" --smbidmapgid="16777216-33554431" --winbindseparator="+" \
--winbindtemplateshell="/bin/false" --enablewinbindusedefaultdomain --disablewinbindoffline \
--winbindjoin=Administrator --disablewins --disablecache --enablelocauthorize --updateall
service winbind start ; chkconfig winbind on
setsebool -P allow_httpd_mod_auth_ntlm_winbind on

Now check your winbind connection using the following commands:
wbinfo -u
wbinfo -g

The socket /var/lib/samba/winbindd_privileged/pipe should be writable by the webserver. To allow that access, I add user apache to the group wbpriv: usermod -G wbpriv apache

Step 4. Download and compile mod_auth_ntlm_winbind

svn co svn://svnanon.samba.org/lorikeet/trunk/mod_auth_ntlm_winbind mod_auth_ntlm_winbind
cd mod_auth_ntlm_winbind/
autoconf
./configure
apxs -DAPACHE2 -c -i mod_auth_ntlm_winbind.c

Step 5. Configure it

In /etc/httpd/conf.d/mod_auth_ntlm_winbind.conf I put the following configuration
LoadModule auth_ntlm_winbind_module /usr/lib64/httpd/modules/mod_auth_ntlm_winbind.so

Options ExecCGI
AllowOverride None
Order allow,deny
Allow from all
AuthName "NTLM Authentication"
AuthType NTLM
Require valid-user
NTLMAuth on
NTLMAuthHelper "/usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp"
NTLMBasicAuthoritative on

In /etc/httpd/conf/httpd.conf, change KeepAlive Off to KeepAlive On. Preferably, also set MaxKeepAliveRequests and KeepAliveTimeout to a high value. On my intranet server, they're set to 1000 requests and 600 seconds.:w

Step 6. Change your firewall to enable incoming HTTP

iptables -I INPUT -p tcp --dport 80 -j ACCEPT
service iptables save

Step 7. Go!

Run service httpd restart, make httpd start on reboot using chkconfig httpd on and test your configuration.

© GeekLabInfo Install mod_auth_ntlm_winbind on CentOS 6.0 is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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