>The trace you have above is Squids view of things. You need to send -d >to the helper itself (if available) to get the helpers view of whats >going on inside there. Indeed, the client seems broken. In that case, there are extra spaces appended after the user name : [2011/08/12 17:20:30, 3] libsmb/ntlmssp.c:ntlmssp_server_auth(739) Got user=[expinet.colissimo ] domain=[PICHON] workstation=[TSE1] len1=24 len2=24 [2011/08/12 17:20:30, 3] utils/ntlm_auth.c:winbind_pw_check(515) Login for user [PICHON]\[expinet.colissimo ]@[TSE1] failed due to [No such user] [2011/08/12 17:20:30, 10] utils/ntlm_auth.c:manage_squid_ntlmssp_request(781) NTLMSSP NT_STATUS_NO_SUCH_USER When it's OK, I get : [2011/08/12 17:20:28, 3] libsmb/ntlmssp.c:ntlmssp_server_auth(739) Got user=[expinet.colissimo] domain=[PICHON] workstation=[TSE1] len1=24 len2=24 [2011/08/12 17:20:28, 10] libsmb/ntlmssp.c:ntlmssp_server_auth(805) ntlmssp_server_auth: Created NTLM2 session key. [2011/08/12 17:20:28, 3] libsmb/ntlmssp_sign.c:ntlmssp_sign_init(338) NTLMSSP Sign/Seal - Initialising with flags: [2011/08/12 17:20:28, 3] libsmb/ntlmssp.c:debug_ntlmssp_flags(63) Got NTLMSSP neg_flags=0xa2088205 NTLMSSP_NEGOTIATE_UNICODE NTLMSSP_REQUEST_TARGET NTLMSSP_NEGOTIATE_NTLM NTLMSSP_NEGOTIATE_ALWAYS_SIGN NTLMSSP_NEGOTIATE_NTLM2 NTLMSSP_NEGOTIATE_128 NTLMSSP_NEGOTIATE_56 [2011/08/12 17:20:28, 10] utils/ntlm_auth.c:manage_squid_ntlmssp_request(784) NTLMSSP OK! Thanks a lot for your help Amos !!!