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! 9: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
! 10: <b>:</b> <A HREF="mpd64.html"><EM>Internals</EM></A>
! 11: <b>:</b> <EM>Authentication</EM><BR>
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! 17: <H2><A NAME="66"></A>8.2. Authentication<A NAME="authentication"></A></H2>
! 18: <p>This chapter describes implementation specific details of MPD.</p>
! 19: <p>
! 20: <dl>
! 21:
! 22: <dt><b>Authentication protocols - a short overview</b><dd><p>Currently MPD supports these authentication protocols: PAP, MD5-CHAP,
! 23: MS-CHAPv1, MS-CHAPv2 and EAP.</p>
! 24: <p>When using PAP, the password is sent as plaintext over the network,
! 25: therefore PAP should be avoided, if the link between the peers is
! 26: not secure. On the other hand, PAP allows using any kind of password
! 27: database on the server, even if the passwords are stored in
! 28: non-reversible hashed format.</p>
! 29: <p>The traditional CHAP-MD5 needs the plaintext password stored on the
! 30: server. The password hash is computed like this: md5(id + password
! 31: + challenge), where the id is incremented after each authentication
! 32: attempt. The challenge is generated by the server and then sent to the
! 33: client (peer). The peer sends the hash to the server and the server
! 34: genrates himself the hash using the plaintext password. If both
! 35: hash are the same, the authentication succeeds.</p>
! 36: <p>MS-CHAP doesen't need plaintext passwords on the server, but does
! 37: need the hashed password either as NT-Hash or as LAN-Manager-Hash
! 38: (the LAN-Manager-Hash is weak and shouldn't be used).
! 39: MS-CHAPv1 uses DES as hashing algorithm and is weak, therefore don't
! 40: use it! MS-CHAPv2 uses a peer challenge and a server
! 41: challenge and uses SHA1 as hashing algorithm, so it's much more
! 42: secure then MS-CHAPv1. MS-CHAPv2 requires the NT-Hash be available.</p>
! 43: <p>Usualy UNIX systems have a different non-revertable hashing
! 44: algorithm for passwords, therefore it is not possible to use the
! 45: traditional UNIX password database if you want to use any
! 46: CHAP algorithm, with the exception that FreeBSD versions 5.1 and
! 47: later support the NT-Hash format in the password database
! 48: (configurable via login.conf: <code>passwd_format=nth</code>).
! 49: However MPD doesen't currently support authentication against
! 50: the UNIX password database.</p>
! 51: <p>EAP is an Extensible Authentication Protocol. Mpd supports
! 52: natively only the EAP-Type MD5; other EAP-Types may be used
! 53: in conjunction with a RADIUS server.</p>
! 54: <p>Note: in order for MPPE to work, MS-CHAPv1 or MS-CHAPv2 is
! 55: mandatory, because the MPPE keys are generated using the results
! 56: from authentication.</p>
! 57:
! 58:
! 59: <dt><b>Authentication protocol negotiation</b><dd><p>Starting with MPD 3.14, MPD behaves more intelligently when negotiating
! 60: authentication protocols. MPD searches an internal list of protocols,
! 61: from most to least secure, until a mutually agreeable protocol is found.
! 62: If the link is a PPTP link, then MS-CHAP is most preferrable, otherwise
! 63: MD5-CHAP is most preferrable.</p>
! 64:
! 65: </dl>
! 66: </p>
! 67:
! 68:
! 69: <HR NOSHADE>
! 70: <A HREF="mpd.html"><EM>Mpd 5.6 User Manual</EM></A>
! 71: <b>:</b> <A HREF="mpd64.html"><EM>Internals</EM></A>
! 72: <b>:</b> <EM>Authentication</EM><BR>
! 73: <b>Previous:</b> <A HREF="mpd65.html"><EM>ToDo</EM></A><BR>
! 74: <b>Next:</b> <A HREF="mpd67.html"><EM>Hints for developers</EM></A>
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