SPNEGO trust association interceptor (TAI) troubleshooting tips

SPNEGO trust association interceptor (TAI) troubleshooting tips

Presented here is a list of trouble shooting tips useful in diagnosing Simple and Protected GSS-API Negotiation (SPNEGO) TAI problems and exceptions. The IBM Java Generic Security Service (JGSS) and IBM Simple and Protected GSS-API Negotiation (SPNEGO) providers use a Java virtual machine (JVM) custom property to control trace information. The SPNEGO TAI uses the JRas facility to allow an administrator to trace only specific classes. The following important trace specifications or JVM custom properties should be used to debug the TAI using tracing.

Table 1. SPNEGO TAI trace specifications

Trace Use

com.ibm.security.jgss.debug Set this JVM Custom Property to all to trace through JGSS code. Messages appear in the trace.log file, and SystemOut.log.
com.ibm.security.krb5.Krb5Debug Set this JVM Custom Property to all to trace through the Kerberos5-specific JGSS code. Messages appear in the trace.log file, and SystemOut.log.
com.ibm.ws.security.spnego.* Set this trace on using the console > troubleshooting > Logging and Tracing > server1 > Change Log Detail Levels > com.ibm.ws.security.spnego.*. Messages appear in the trace.log file.

Problem: WAS and the Active Directory (AD) Domain Controller's time are not synchronized within 5 minutes.
Symptom
[2/24/06 13:12:46:093 CST] 00000060 Context       2 com.ibm.ws.security.spnego.Context 
    begin GSSContext accepted
[2/24/06 13:12:46:093 CST] 00000060 Context       E com.ibm.ws.security.spnego.Context 
    begin
CWSPN0011E: An invalid SPNEGO token has been encountered while authenticating a 
    HttpServletRequest:
0000:  60820160 06062b06 01050502 a1820154    `..` ..+. .... ...T
0010:  30820150 a0030a01 01a10b06 092a8648    0..P .... .... .*.H
0020:  82f71201 0202a282 013a0482 01366082    .... .... .:.. .6`.
0030:  01320609 2a864886 f7120102 0203007e    .2.. *.H. .... ...~
0040:  82012130 82011da0 03020105 a1030201    ..!0 .... .... ....
0050:  1ea41118 0f323030 36303232 34313931    .... .200 6022 4191
0060:  3234365a a5050203 016b48a6 03020125    246Z .... .kH. ...%
0070:  a9161b14 57535345 432e4155 5354494e    .... WSSE C.AU STIN
0080:  2e49424d 2e434f4d aa2d302b a0030201    .IBM .COM .-0+ ....
0090:  00a12430 221b0448 5454501b 1a773230    ..$0 "..H TTP. .w20
00a0:  30337365 63646576 2e617573 74696e2e    03se cdev .aus tin.
00b0:  69626d2e 636f6dab 81aa1b81 a76f7267    ibm. com. .... .org
00c0:  2e696574 662e6a67 73732e47 53534578    .iet f.jg ss.G SSEx
00d0:  63657074 696f6e2c 206d616a 6f722063    cept ion,  maj or c
00e0:  6f64653a 2031302c 206d696e 6f722063    ode:  10,  min or c
00f0:  6f64653a 2033370a 096d616a 6f722073    ode:  37. .maj or s
0100:  7472696e 673a2044 65666563 74697665    trin g: D efec tive
0110:  20746f6b 656e0a09 6d696e6f 72207374     tok en.. mino r st
0120:  72696e67 3a20436c 69656e74 2074696d    ring : Cl ient  tim
0130:  65204672 69646179 2c204665 62727561    e Fr iday , Fe brua
0140:  72792032 342c2032 30303620 61742031    ry 2 4, 2 006  at 1
0150:  3a31323a 34352050 4d20746f 6f20736b    :12: 45 P M to o sk
0160:  65776564                               ewed 
User Action The preferred way to resolve this issue is to synchronize the WebSphere Application Server system time to within 5 minutes of the AD server’s time. A best practice is to use a time server to keep all systems synchronized. You can also add or adjust the clockskew parameter in the Kerberos configuration file.
The default for the clockskew parameter is 300 seconds (or 5 minutes).
Problem: No factory available to create a name for mechanism 1.3.6.1.5.5.2.
Problem Getting an exception: No factory available to create a name for mechanism 1.3.6.1.5.5.2. There is no factory available to process the creation of a name for the specific mechanism.
Symptom
[4/8/05 22:51:24:542 EDT] 5003e481 SystemOut     O [JGSS_DBG_PROV] Provider 
        IBMJGSSProvider version 1.01 does not support mech 1.3.6.1.5.5.2
[4/8/05 22:51:24:582 EDT] 5003e481 ServerCredent > 
        com.ibm.ws.security.spnego.ServerCredential initialize ENTRY
SPNEGO014: Kerberos initialization Failure: org.ietf.jgss.GSSException, major code: 2, 
        minor code: 0
  major string: Unsupported mechanism
  minor string: No factory available to create name for mechanism 1.3.6.1.5.5.2
  at com.ibm.security.jgss.i18n.I18NException.throwGSSException
        (I18NException.java:30)
  at com.ibm.security.jgss.GSSManagerImpl.a(GSSManagerImpl.java:36)
  at com.ibm.security.jgss.GSSCredentialImpl.add(GSSCredentialImpl.java:217)
  at com.ibm.security.jgss.GSSCredentialImpl.<init>(GSSCredentialImpl.java:264)
User Action
Check the java.security file to ensure it contains the IBMSPNEGO security provider and that the provider is defined correctly. The java.security file should contain a line similar to:
security.provider.6=com.ibm.security.jgss.mech.spnego.IBMSPNEGO
Problem: Getting an exception as the JGSS library is trying to process the SPNEGO token.
Symptom
The following error is displayed as the JGSS library is trying to process the SPNEGO token.
Error authenticating request. Reporting to client
Major code = 11, Minor code = 31 org.ietf.jgss.GSSException, major code: 11, minor code: 31
  major string: General failure, unspecified at GSSAPI level
  minor string: Kerberos error while decoding and verifying token: 
                com.ibm.security.krb5.internal.KrbException, status code: 31
  message: Integrity check on decrypted field failed
Description
This exception is the result of encoding the ticket using one key and attempting to decode it using a different key. There are number of possible reasons for this condition:
The Kerberos keytab file has not been copied to the server machine after it has been regenerated.

The Kerberos configuration points to the wrong Kerberos keytab file.
The Kerberos service principal name (SPN) has been defined to the Active Directory more than once. You have another userid defined with the same SPN or defined with the same SPN with a port defined also. The following example demonstrates how this condition can occur:
SAME SPN but different user ids
setspn -a HTTP/myHost.austin.ibm.com user1
  setspn -a HTTP/myHost.austin.ibm.com user2
SAME SPN and same user ids, one without a port number, one with a port number
setspn -a HTTP/myHost.austin.ibm.com user
  setspn -a HTTP/myHost.austin.ibm.com:9080 user
User Action
If the problem is with the Kerberos keytab file, then fix it. If the problem is with multiple SPN definitions, then remove the extra or conflicting SPN, confirm that the SPN is no longer registered with the Active Directory, and then add the SPN. The Active Directory may need to be searched for other entries with SPNs defined that clash with the SPN.To confirm that the SPN is not registered, the command:
setspn –l userid
should return with the following response:
Cannot find account userid
Problem: Single sign-on is not occurring.
Symptom
When tracing is enabled, the following message appears:
[2/27/06 14:28:04:191 CST] 00000059 SpnegoHandler < 
         com.ibm.ws.security.spnego.SpnegoHandler handleRequest: Received a 
         non-SPNEGO Authorization Header RETURN
Description
The client is returning an NT LAN manager (NTLM) response to the authorize challenge, not a SPNEGO token. This condition can be occur due to any of the following reasons:
The client has not been configured properly.

The client is not using a supported browser. For example, when using Microsoft Internet Explorer 5.5, SP1 responds with a non-SPNEGO authentication header.

The user has not logged into the Active Directory domain, or into a trusted domain, or the client used does not support integrated authentication with Windows – in this case, the SPNEGO TAI is working properly.

The user is accessing a service defined on the same machine upon which the client is running (local host). Microsoft Internet Explorer resolves the host name of the URL to http://localhostsomeURL instead of a fully qualified name.
The SPN is not found in the Active Directory. The SPN must be of the format HTTP/server.realm.com. The command to add the SPN is
setspn –a HTTP/server.realm.com userid
User Action If the SPN is defined incorrectly as HTTP/server.realm.com@REALM.COM with the addition of @REALM.COM, then delete the user, redefine the user, and redefine the SPN.
Problem: Credential Delegation is not working.
Symptom
An invalid option is detected. When tracing is enabled, the following message is displayed:
com.ibm.security.krb5.KrbException, status code: 101 message: Invalid option in  ticket request
Description The Kerberos configuration file is not properly configured.
User Action Ensure that neither renewable, nor proxiable are set to true.
Problem: Unable to get SSO working using RC4-HMAC encryption.
Symptom
Examine the following message in the trace that you receive when trace is turned on:
com.ibm.security.krb5.internal.crypto.KrbCryptoException, status code: 0
  message: Checksum error; received checksum does not match computed checksum
Description
RC4-HMAC encryption is not supported with a Microsoft Windows 2000 Kerberos key distribution center (KDC). To confirm this condition, examine the trace and identify where the exception is thrown. The content of the incoming ticket should be visible in the trace. Although the incoming ticket is encrypted, the SPN for the service is readable. If a Microsoft Windows 2000 KDC is used and the system is configured to use RC4-HMAC, the string representing the ticket for userid@REALM ( instead of the expected HTTP/hostname.realm@REALM) is displayed. For example, this is beginning of the ticket received from a Microsoft Windows 2000 KDC:
0000: 01 00 6e 82 04 7f 30 82  04 7b a0 03 02 01 05 a1  ..n...0.........
0010: 03 02 01 0e a2 07 03 05  00 20 00 00 00 a3 82 03  ................
0020: a5 61 82 03 a1 30 82 03  9d a0 03 02 01 05 a1 0a  .a...0..........
0030: 1b 08 45 50 46 44 2e 4e  45 54 a2 18 30 16 a0 03  ...REALM.COM.0..
0040: 02 01 01 a1 0f 30 0d 1b  0b 65 70 66 64 77 61 73  .....0...userid
0050: 75 6e 69 74 a3 82 03 6e  30 82 03 6a a0 03 02 01  .a.f...n0..j....
The realm is REALM.COM. The service name is userid. A correctly formed ticket for the same SPN is:
0000: 01 00 6e 82 04 56 30 82  04 52 a0 03 02 01 05 a1  ..n..V0..R......
0010: 03 02 01 0e a2 07 03 05  00 20 00 00 00 a3 82 03  ................
0020: 82 61 82 03 7e 30 82 03  7a a0 03 02 01 05 a1 0a  .a...0..z.......
0030: 1b 08 45 50 46 44 2e 4e  45 54 a2 2a 30 28 a0 03  ..REALM.COM.0...
0040: 02 01 02 a1 21 30 1f 1b  04 48 54 54 50 1b 17 75  .....0...HTTP..u
0050: 73 31 30 6b 65 70 66 77  61 73 73 30 31 2e 65 70  serid.realm.com.
0060: 66 64 2e 6e 65 74 a3 82  03 39 30 82 03 35 a0 03  ...n.....90..5..
User Action To correct the problem, either use the Single data encryption standard (DES) or use a Microsoft Windows 2003 Server for a KDC. Remember to regenerate the SPN, and the Kerberos keytab file.
Problem: User receives the following message when accessing a protected URL through the SPNEGO SSO.
Symptom
Examine the following message:
Bad Request

Your browser sent a request that this server could not understand.
Size of request header field exceeds server limit.

Authorization: Negotiate YII……
Description This message is generated by the Apache/IBM HTTP Server. This server is indicating that the authorization header returned by the user’s browser is too large. The long string that follows the word Negotiate (in the error message above) is the SPNEGO token. This SPNEGO token is a wrapper of the Microsoft Windows Kerberos token. Microsoft Windows includes the user’s PAC information in the Kerberos token. The more security groups that the user belongs to, the more PAC information is inserted in the Kerberos token, and the larger the SPNEGO becomes. IBM HTTP Server 2.0 (also Apache 2.0 and IBM HTTP Server 6.0) limit the size of any acceptable HTTP header to be 8K. In Microsoft Windows domains having many groups, and with user membership in many groups, the size of the user’s SPNEGO token may exceed the 8K limit.
User Action If possible, reduce the number of security groups the user is a member of. IBM HTTP Server 2.0.47 cumulative fix PK01070 allows for HTTP header sizes up to and beyond the Microsoft limit of 12K. WAS V6.0 users can obtain this fix in fixpack 6.0.0.2.
Non-Apache based Web servers may require differing solutions.
Problem: Even with JGSS tracing disabled, some KRB_DBG_KDC messages appear in the SystemOut.log.
Symptom Examine the SystemOut.log and note the some KRB_DBG_KDC messages appear there even with JGSS tracing disabled.
Description While most of the JGSS tracing is controlled by the com.ibm.security.jgss.debug property, a small set of messages are controlled by the com.ibm.security.krb5.Krb5Debug property. The com.ibm.security.krb5.Krb5Debug property has a default value to put some messages to the SystemOut.log
User Action
.To remove all KRB_DBG_KDC messages from the SystemOut.log, set the JVM property as follows:
-Dcom.ibm.security.krb5.Krb5Debug=none
Problem: When an application contains a custom HTTP 401 error page, the SPNEGO TAI-generated HTTP response page is not displayed in a browser.

Symptom When an application contains a custom HTTP 401 error page, the Simple and Protected GSS-API Negotiation Mechanism (SPNEGO) trust association interceptor (TAI)-generated HTTP response page is not displayed in a browser.
Description When an application contains a custom HTTP 401 error page, the SPNEGO TAI-generated HTTP response page is not displayed in a browser. The custom HTTP 401 error page is displayed instead.
User Action You can customize your HTTP 401 page to include information concerning how to configure your browser to use SPNEGO. For more information, see Configure the Web browser to use SPNEGO and SPNEGO TAI custom configuration attributes

Problem: HTTP Post parameters are lost during interaction with the SPNEGO TAI, when stepping down to userid/password login.
Symptom Note that HTTP Post parameters are lost during interaction with the SPNEGO TAI, when stepping down to userid/password login.
"Stepping down to userid/password login" means that the Microsoft Internet Explorer tries to respond initially with a SPNEGO token. If this response is unsuccessful, then the Microsoft Internet Explorer tries to respond with a NTLM token that is obtained through a userid/password challenge.
Description The Microsoft Internet Explorer maintains state during a user’s request. If a request was given the response of an "HTTP 401 Authenticate Negotiate", and the browser responds with a NTLM token obtained through a userid/password challenge, the browser resubmits the request. If this second request is given a response of an HTML page containing a redirection to the same URL but with new arguments (via Javascript) then the browser does not resubmit the POST parameters.
To avoid this problem, it is critical to NOT perform the automatic redirection. If the user clicks on a link, the problem does not occur.
User Action
The browser responds to the Authenticate/Negotiate challenge with an NTLM token, not an SPNEGO token. The SPNEGO TAI sees the NTLM, and returns back a HTTP 403 response, along with the HTML page. When the browser runs the Javascript redirTimer function, any POST of GET parameters that were present on the original request are lost. By leveraging the SPN<id>.NTLMTokenReceivedPage property, an appropriate message page can be returned to the user. The default message that is returned (in the absence of a user defined property) is:
"<html><head><title>An NTLM Token was Received.</title></head>"
  + "<body>Your browser configuration is correct, but you have not logged into 
           a supported Windows Domain."
  + "<p>Please login to the application using the normal login page.</html>";
Use the SPN<id>.NTLMTokenReceivedPage property, you can customize the exact response. It is critical that the returned HTML not perform a redirection.
When the SPNEGO TAI has been configured to use the shipped default HTTPHeaderFilter class as the SPN<id>.filterClass, then the SPN<id>.filter can be used to allow the second request to flow directly to the normal WAS security mechanism. In this way, the user experiences the normal authentication mechanism. An example of such a configuration follows. The required SPNEGO TAI properties necessary and the HTML file content are presented.

Table 2. SPNEGO TAI properties and HTML

SPNEGO TAI Property Name HTML File Content

com.ibm.ws.security.spnego.SPN1.hostName server.wasteched30.torolab.ibm.com
com.ibm.ws.security.spnego.SPN1.filterClass com.ibm.ws.security.spnego.HTTPHeaderFilter
com.ibm.ws.security.spnego.SPN1.filter request-url!=noSPNEGO
com.ibm.ws.security.spnego.SPN1.NTLMTokenReceivedPage File:///C:/temp/NTLM.html

Observe that the filter property instructs the SPNEGO TAI to NOT intercept any HTTP request that contains the string “noSPNEGO”. Here is an example of a generating a helpful response.
<html>
<head>
<title>NTLM Authentication Received </title>
<script language="javascript">
  var purl=""+document.location; if (purl.indexOf("noSPNEGO")<0) {
    if(purl.indexOf('?')>=0) purl+="&noSPNEGO";
    else purl+="?noSPNEGO";
  }
</script>
</head>
<body>
<p>An NTLM token was retrieved in response to the SPNEGO challenge. It is likely that 
you are not logged into a Windows domain.<br>
Click on the following link to get the requested website.
<script language="javascript">
  document.write("<a href='"+purl+"'>");
  document.write("Open the same page using the normal authentication 
  mechanism.");
  document.write("</a><br>");
</script>
You will not automatically be redirected.
</body>
</html>
Related concepts

Single sign-on for HTTP requests using SPNEGO

Related tasks

Configure SPNEGO TAI in WAS
Configure JVM properties and enabling SPNEGO TAI in WebSphere Application Server
Creating the Kerberos configuration file for use with the SPNEGO TAI
Troubleshooting security configurations

Related Reference

SPNEGO TAI JVM configuration attributes
Kerberos configuration requirements for SPNEGO TAI
SPNEGO TAI custom configuration attributes

Reference topic

Trace	Use
com.ibm.security.jgss.debug	Set this JVM Custom Property to all to trace through JGSS code. Messages appear in the trace.log file, and SystemOut.log.
com.ibm.security.krb5.Krb5Debug	Set this JVM Custom Property to all to trace through the Kerberos5-specific JGSS code. Messages appear in the trace.log file, and SystemOut.log.
com.ibm.ws.security.spnego.*	Set this trace on using the console > troubleshooting > Logging and Tracing > server1 > Change Log Detail Levels > com.ibm.ws.security.spnego.*. Messages appear in the trace.log file.

Symptom	When an application contains a custom HTTP 401 error page, the Simple and Protected GSS-API Negotiation Mechanism (SPNEGO) trust association interceptor (TAI)-generated HTTP response page is not displayed in a browser.
Description	When an application contains a custom HTTP 401 error page, the SPNEGO TAI-generated HTTP response page is not displayed in a browser. The custom HTTP 401 error page is displayed instead.
User Action	You can customize your HTTP 401 page to include information concerning how to configure your browser to use SPNEGO. For more information, see Configure the Web browser to use SPNEGO and SPNEGO TAI custom configuration attributes