13. Network Protocols

MIT 6.858 Computer Systems Security, Fall 2014
View the complete course: ocw.mit.edu/6-8...
Instructor: Nickolai Zeldovich
In this lecture, Professor Zeldovich discusses the Kerberos authentication service.
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu

[@veramentegina]

I love Dr. Nickolai's enthusiasm and passion in lecturing. Pleasure to listen to him teaching. He makes it fun.

[@عبدالغني-ب9ص]

In kerberos once the auth is a success a TGT is issued and presented to the TGS, once the TGS confirms the TGT the user is granted access to the service. Auth -> auth service TGT -> ticket granting ticket (temporary validity) TGS -> ticket granting server The combination of these three is royally referred to as The Key Distribution Center. The KDC serves as the central authority responsible for authenticating users, issuing tickets, and facilitating secure communication within the Kerberos realm.

[@JMROMERO95]

I think this was a really good lecture... However, I'd suggest to change the title. It must be called "Kerberos protocol" or something like that. But still, very, very, veeeery good lecture. :)

[@noguide]

I don't know how many other OCW MIT courses you have done, but what I have observed is that MIT's approach to teaching seems to be to use a case study, like Kerberos in this lecture, to explain general principles, rather than the other way around, as is often the case in lesser universities. They have a long history of teaching non trivial concepts, and must have found that this approach is better pedagogically, and rather than starting the lectures with pure theory they have found that starting with something concrete works much better. MIT's goal is also to teach students how to think critically about systems, rather than just taking theory at face value. This is best accomplished with case studies. This approach is very obvious in the prereq for this course, the excellent 6.033. Why else do you think the professor asks so many questions, why this, why that, make students participate? It is so that students can discover, think about and learn general principles from a concrete example, rather than memorizing blindly. This kind of interaction is only possible during a lecture; you can learn theory by reading a book (or books), which by now should be obvious to you that you must do to complement the lecture. This lecture actually forms a continuum with the next lecture (SSL & HTTPS). Why start with a less familiar protocol, like Kerberos? The reason is that it deals with a simpler problem, at a smaller scale. Conclusion: this is lecture is not really about Kerberos, and the title is right. I want to stress this point, because it is crucial if you don't want to be disappointed by MIT OCW courses: MIT's philosophy is not to teach specific technologies or the latest fads, but rather to hammer in timeless principles that will be applicable to whichever technology happens to be in vogue. Once you understand the general principles well, learning the details by yourself is a walk in the park. If you don't like this approach then you should try other courses.

[@captain6876]

@@noguide manz sounds offended.

[@jamesf6039]

@@captain6876 Your comment is useless garbage

[@TheLous113]

How to discover the password by brute force as the teacher asked at the minute 31:15? The password is hashed on Kc. But the attacker does not know the Kc, only the encrypted message: {{Tc,s}Ks, Kc,s}Kc. He can try brute force the encrypted message: {{Tc,s}Ks, Kc,s}Kc, but he has no idea what is the true value of {{Tc,s}Ks, Kc,s}Kc, he can try all Kc possibles, include the correct key, and he won't know if the result found is the correct one.

[@عبدالغني-ب9ص]

couldn't have said better, the system is designed to exhaust the idea of brute forcing. Afterall, how are you suppose to brute force a system that has rate limiting and account lockout policies let alone the other features.

So I thank God there are Stanford classes available on youtube, while some guys just leave in the middle of lesson

[@conallogribin]

They realise they aren't worthy. it's only fair ;)

[@Arbiteroflife]

This is MIT

[@makharsa12]

Aside from the great lecture, the accent is just top notch. Thanks MIT

[@fwily2580]

Reminds me of my community college teacher.

[@RohitSoni010]

Can somebody tell me that " How credentials are synced between server and kdc". Thanks in advance

[@taiquangong9912]

Passing the hash would work here.

[@peppigue]

I really like this guy, but this particular lecture was a mess. Wish it centered on a visualization of client, server, key server, and attacker. Then point out how each implementation discussed related to/fit in in that picture.

[@shyamkedia4202]

you skip first 20 seconds until you realize you are addicted to them!

[@mariofredrick1501]

nice

[@tlopez5069]

Which textbooks are used for this course?

[@mitocw]

See the Readings section for details: ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-858-computer-systems-security-fall-2014/readings/. Best wishes on your studies!

[@bikeshack8225]

if I make a comment about wumao will it be censored by youtube?

[@YouMeverse]

IIT NPTEL lectures are more systematic and better compared to MIT. They are using big boards and chocks, which is very annoying.

[@cjonam]

guy just walked away in middle of class..will never happen in india :)

[@TheDavidlloydjones]

Higher education over the Internet is *the* killer app of the 21st century. It therefore seems sorta dumb to be cluttering it up with all that stuff at the beginning about classrooms. Or is this yer avvidge normal corroborative detail intended to give some similitude of veracity to an otherwise bald and uninteresting narrative? (Tip o' the 'at...) -dlj.

[@MAlgMAlg1]

www.reddit.com/r/iamverysmart/

[@marineplaysairsoft]

www.nimh.nih.gov/health/topics/schizophrenia/index.shtml

[@24reyeser]

This professor is so bad

[@captain6876]

Ikr