I have configured squid with AD authentication its working fine but I am getting lots of error for authentication failed. squid-2.5.STABLE14-1.4E samba-3.0.10-1.4E.11 Windows 2003 Domain Audit log failure. Pre-authentication failed: User Name: proxy$ User ID: DOMAIN\proxy$ Service Name: krbtgt/DOMAIN.HOME Pre-Authentication Type: 0x0 Failure Code: 0x19 Client Address: 10.1.5.12 For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. /etc/samba/smb.conf [global] workgroup = DOMAIN netbios name = PROXY realm = DOMAIN.HOME server string = Linux Samba Server security = ads encrypt passwords = Yes password server = 10.1.5.11 log file = /var/log/samba/%m.log max log size = 0 socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192 preferred master = False local master = No domain master = False dns proxy = No wins server = 10.1.5.11 # winbind separator = / winbind enum users = yes winbind enum groups = yes winbind use default domain = yes idmap uid = 10000-20000 idmap gid = 10000-20000 client schannel = no log file = /var/log/samba/%m.log max log size = 50 [homes] comment = Home Directories browseable = no writable = yes [printers] comment = All Printers path = /var/spool/samba browseable = no guest ok = no writable = no printable = yes /etc/krb5.conf [logging] default = FILE:/var/log/krb5libs.log kdc = FILE:/var/log/krb5kdc.log admin_server = FILE:/var/log/kadmind.log [libdefaults] #ticket_lifetime = 24000 default_realm = DOMAIN.HOME dns_lookup_realm = false dns_lookup_kdc = false [realms] DOMAIN.HOME = { kdc = 10.1.5.11 admin_server = 10.1.5.11 default_domain = DOMAIN.HOME } [domain_realm] .DOMAIN.home = DOMAIN.HOME DOMAIN.home = DOMAIN.HOME [kdc] profile = /var/kerberos/krb5kdc/kdc.conf [appdefaults] pam = { debug = false ticket_lifetime = 36000 renew_lifetime = 36000 forwardable = true krb4_convert = false }