172 lines
3.9 KiB
Plaintext
172 lines
3.9 KiB
Plaintext
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Network Working Group Assar Westerlund
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<draft-ietf-cat-krb5-tcp.txt> SICS
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Internet-Draft Johan Danielsson
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November, 1997 PDC, KTH
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Expire in six months
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Kerberos over TCP
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Status of this Memo
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This document is an Internet-Draft. Internet-Drafts are working
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documents of the Internet Engineering Task Force (IETF), its areas,
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and its working groups. Note that other groups may also distribute
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working documents as Internet-Drafts.
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Internet-Drafts are draft documents valid for a maximum of six months
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and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet- Drafts as reference
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material or to cite them other than as "work in progress."
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To view the entire list of current Internet-Drafts, please check the
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"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
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Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe),
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munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
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ftp.isi.edu (US West Coast).
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Distribution of this memo is unlimited. Please send comments to the
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<cat-ietf@mit.edu> mailing list.
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Abstract
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This document specifies how the communication should be done between
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a client and a KDC using Kerberos [RFC1510] with TCP as the transport
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protocol.
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Specification
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This draft specifies an extension to section 8.2.1 of RFC1510.
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A Kerberos server MAY accept requests on TCP port 88 (decimal).
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The data sent from the client to the KDC should consist of 4 bytes
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containing the length, in network byte order, of the Kerberos
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request, followed by the request (AS-REQ or TGS-REQ) itself. The
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reply from the KDC should consist of the length of the reply packet
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(4 bytes, network byte order) followed by the packet itself (AS-REP,
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TGS-REP, or KRB-ERROR).
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Westerlund, Danielsson [Page 1]
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Internet Draft Kerberos over TCP November, 1997
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C->S: Open connection to TCP port 88 at the server
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C->S: length of request
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C->S: AS-REQ or TGS-REQ
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S->C: length of reply
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S->C: AS-REP, TGS-REP, or KRB-ERROR
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Discussion
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Even though the preferred way of sending kerberos packets is over UDP
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there are several occasions when it's more practical to use TCP.
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Mainly, it's usually much less cumbersome to get TCP through
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firewalls than UDP.
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In theory, there's no reason for having explicit length fields, that
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information is already encoded in the ASN1 encoding of the Kerberos
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packets. But having explicit lengths makes it unnecessary to have to
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decode the ASN.1 encoding just to know how much data has to be read.
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Another way of signaling the end of the request of the reply would be
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to do a half-close after the request and a full-close after the
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reply. This does not work well with all kinds of firewalls.
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Security considerations
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This memo does not introduce any known security considerations in
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addition to those mentioned in [RFC1510].
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References
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[RFC1510] Kohl, J. and Neuman, C., "The Kerberos Network
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Authentication Service (V5)", RFC 1510, September 1993.
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Authors' Addresses
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Assar Westerlund
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Swedish Institute of Computer Science
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Box 1263
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S-164 29 KISTA
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Sweden
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Phone: +46-8-7521526
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Fax: +46-8-7517230
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EMail: assar@sics.se
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Johan Danielsson
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PDC, KTH
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S-100 44 STOCKHOLM
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Westerlund, Danielsson [Page 2]
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Internet Draft Kerberos over TCP November, 1997
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Sweden
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Phone: +46-8-7907885
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Fax: +46-8-247784
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EMail: joda@pdc.kth.se
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Westerlund, Danielsson [Page 3]
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