Is it required to use GSSAPI code for the Kerberos Server Auth?

[Surendra Babu A]

  Hi Team,

  Could you please let me know your thoughts on the below mentioned issue.

  Point #1
  ----------
  I am working on SA (Server Authentication) feature of Kerberos.
  - Is it required to port GSSAPI code for this feature of SA?
  - If so, where should I use this mechansim in kerberos client code? That
means, between TGS_REP and AP_REQ?
  - What is the exact procedure to use the GSSAPI code?

  I am using MIT code and Linux Serevr (sendmail server, SMTP as the
Application server, ie I need to do server authenticatio for that SMTP
server.

  POINT#2:
  ----------
  I tried by sending AP_REQ to SMTP server successfuly but I could not
recevice the AP_REP successfuly. I think AP_REQ packet is not properly
understood by SMTP server since I have not been using the GSSAPI code in my
implementation. So should I port the GSSAPI code in to my code base and do
SA??

  POINT#3:
  ======
  - Is the following statement reight?
  Kerberos Server Authentication is not supported by Windows 2003/2000
exchange SMTP server.
  Kerberos SA can be done (only) with LINUX/Unix- Send mail SMTP server.

  Is this statement true????

  Could you please throw some light on the same?

  Thank you,
  -Surendra