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NTLM authentication

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Sagi
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Sagi asked on 11 Mar 2015, 08:10 AM
Hi,
I'm using NTLM authentication in my site .
I'm trying to find out how can I extract the User Name sent to the server by the client.
After reading MS article  (https://msdn.microsoft.com/en-us/library/windows/desktop/aa378749%28v=vs.85%29.aspx) I thought that the User Name is sent from the client after the first 401 challenge the server sends. (which means the scond request the client initiates)
However , when looking in Fiddler I have realized that the second request from the client (after the first 401) did not include the User Name
Only the third request (ending with 200 status code) included the User Name (as plain Text).
Can you please explain ?
_________________________________________________
First Request ended with 401 ;
No Proxy-Authorization Header is present.

No Authorization Header is present.
_________________________________________________



_________________________________________________
Second request ended with 401 (challenge from server)

No Proxy-Authorization Header is present.

Authorization Header is present: Negotiate
4E 54 4C 4D 53 53 50 00 01 00 00 00 97 82 08 E2  NTLMSSP.....—‚.â
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
06 02 F0 23 00 00 00 0F                          ..ð#....        


-[NTLM Type1: Negotiation]------------------------------
Provider: NTLMSSP
Type: 1
OS Version: 6.2:9200
Flags: 0xe2088297
Unicode supported in security buffer.
OEM strings supported in security buffer.
Request server's authentication realm included in Type2 reply.
Sign (integrity)
NTLM authentication.
Negotiate Always Sign.
Negotiate NTLM2 Key.
Supports 56-bit encryption.
Supports 128-bit encryption.
Client will provide master key in Type 3 Session Key field.
Domain_Offset: 0; Domain_Length: 0; Domain_Length2: 0
Host_Offset: 0; Host_Length: 0; Host_Length2: 0
Host: 
Domain: 
------------------------------------



_________________________________________________
third request ended with 200

No Proxy-Authorization Header is present.

Authorization Header is present: Negotiate
4E 54 4C 4D 53 53 50 00 03 00 00 00 18 00 18 00  NTLMSSP.........
80 00 00 00 18 00 18 00 98 00 00 00 06 00 06 00  €.......˜.......
58 00 00 00 0C 00 0C 00 5E 00 00 00 16 00 16 00  X.......^.......
6A 00 00 00 10 00 10 00 B0 00 00 00 15 82 88 E2  j.......°....‚ˆâ
06 02 F0 23 00 00 00 0F 6F 4B 84 5D 4A 6A 67 C5  ..ð#....oK„]JjgÅ
49 E7 9B E6 ED D5 B9 9F 47 00 45 00 52 00 73 00  Iç›æíÕ¹ŸG.E.R.s.
6B 00 61 00 72 00 6E 00 69 00 53 00 4B 00 41 00  k.a.r.n.i.S.K.A.
52 00 4E 00 49 00 2D 00 4D 00 4F 00 42 00 4C 00  R.N.I.-.M.O.B.L.
26 FB C4 DC FC BE 0B 6A 00 00 00 00 00 00 00 00  &ûÄÜü¾.j........
00 00 00 00 00 00 00 00 64 0B 2C 82 FA 33 05 17  ........d.,‚ú3..
CF 6D 43 44 06 C0 F0 50 5D EA E3 E5 34 69 38 B4  ÏmCD.ÀðP]êãå4i8´
E8 F1 E0 A5 46 72 6F CF D3 36 4A 25 BB 0D DF 16  èñà¥FroÏÓ6J%».ß.


-[NTLM Type3: Authentication]------------------------------
Provider: NTLMSSP
Type: 3
OS Version: 6.2:9200
Flags: 0xe2888215
Unicode supported in security buffer.
Request server's authentication realm included in Type2 reply.
Sign (integrity)
NTLM authentication.
Negotiate Always Sign.
Negotiate NTLM2 Key.
Target Information block provided for use in calculation of the NTLMv2 response.
Supports 56-bit encryption.
Supports 128-bit encryption.
Client will provide master key in Type 3 Session Key field.
lmresp_Offset: 128; lmresp_Length: 24; lmresp_Length2: 24
ntresp_Offset: 152; ntresp_Length: 24; ntresp_Length2: 24
Domain_Offset: 88; Domain_Length: 6; Domain_Length2: 6
User_Offset: 94; User_Length: 12; User_Length2: 12
Host_Offset: 106; Host_Length: 22; Host_Length2: 22
msg_len: 176
Domain: GER
User: skarni
Host: SKARNI-MOBL
lm_resp: 26 FB C4 DC FC BE 0B 6A 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
nt_resp: 64 0B 2C 82 FA 33 05 17 CF 6D 43 44 06 C0 F0 50 5D EA E3 E5 34 69 38 B4
------------------------------------

_________________________________________________

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Eric Lawrence
Telerik team
answered on 13 Mar 2015, 02:37 PM
Hello, Sagi--

The article you linked describes the NTLM process in the abstract, not in terms of its implementation over HTTP. For that, you should see Microsoft's formal standard document: https://msdn.microsoft.com/en-us/library/cc237488.aspx


Regards,
Eric Lawrence
Telerik
 

Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

 
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