I was just reading up on Kerberos and realized that the lifetime of a master ticket called the TGT(ticket granting ticket) is 25 hours. Is there any particular reason behind this choice of lifetime?


The Kerberos (v5) RFC does not specify a lifetime but recommends nothing more than 25 hours life for each ticket (section 8.2) and a renewal time of max. one week. There is probably no good answer here as to why Stanford chose to break that recommendation.

  • Okay -- but any thoughts on why "25 hours" was chosen? Seems a bit odd to me.
    – user1187
    Nov 13 '12 at 12:21
  • No, really no idea. Long hours at Stanford? Being a university, I would guess they have actually discussed and written down somewhere why they chose 25, but finding out who did or where could be a problem. Nov 13 '12 at 12:25
  • 3
    My assumption would be that they made it just long enough that they could renew a ticket for the next day before expiry. Just a guess.
    – Rory Alsop
    Nov 13 '12 at 17:30

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