>вместо "TEST\\internet" поставь его sid

[root@centos ~]# wbinfo -n internet
S-1-5-21-467374765-1553341467-3494682542-1142 Domain Group (2)
[root@centos ~]#

в squid.conf

auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --require-membership-of="S-1-5-21-467374765-1553341467-3494682542-1142"
auth_param ntlm children 30
auth_param basic program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-basic --require-membership-of="S-1-5-21-467374765-1553341467-3494682542-1142"
auth_param basic children 4
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 2 hours

acl internet proxy_auth REQUIRED
http_access allow internet

в access.log

1228816530.215      1 192.168.252.129 TCP_DENIED/407 1787 GET http://google.ru/ - NONE/- text/html
1228816530.246      7 192.168.252.129 TCP_DENIED/407 1855 GET http://google.ru/ - NONE/- text/html
1228816530.262     16 192.168.252.129 TCP_DENIED/403 1435 GET http://google.ru/ TEST\test NONE/- text/html

smb.conf:

[global]
workgroup = TEST
netbios name = centos
server string = Samba Server 3.0
security = ads
realm = TEST.LOCAL
password server = 192.168.252.129

#только что добавил ради того что бы убрать netbios имя TEST. TEST\test
winbind separator = +
winbind use default domain = yes

encrypt passwords = yes
printcap name = /etc/printcap
load printers = yes
printing = cups
log file = /var/log/samba/%m.log
max log size = 0
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
local master = no
domain master = no
preferred master = no
dns proxy = no

В squid.conf (покажу целиком).
http_port 192.168.252.130:3128
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY
cache_dir ufs /etc/squid/cache 200 32 384
cache_access_log /var/log/squid/access.log
cache_log /var/log/squid/cache.log
cache_swap_log /var/log/squid/swap.log
cache_store_log none

auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 30

auth_param basic program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-basic
auth_param basic children 4
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 2 hours

acl all src 192.168.252.100

acl internet proxy_auth REQUIRED
http_access allow internet
http_access allow all

cache_effective_user squid
cache_effective_group squid

В логах:
1228828525.215      4 192.168.252.129 TCP_DENIED/407 1799 GET http://www.google.ru/ - NONE/- text/html
1228828525.236     12 192.168.252.129 TCP_DENIED/407 1867 GET http://www.google.ru/ - NONE/- text/html
1228828525.568    331 192.168.252.129 TCP_DENIED/403 1428 GET http://www.google.ru/ test DIRECT/64.233.183.103 text/html