AUTH(5)
NAME
auth − file system authentication
SYNOPSIS
Tauth tag[2] fid[2] uid[28] chal[36]
Rauth tag[2] fid[2] chal[30]
DESCRIPTION
The auth message is used to authorize a connection. It is issued before an attach. Fid and uid are the same as for attach.
The chal field of a Tauth message contains a 36-byte string encrypted with the client’s authentication key. The (decrypted) string contains a byte with value 1, a seven byte client challenge, and the server’s name NUL-padded to 28 (NAMELEN) bytes.
The chal field of the Rauth reply message is also encrypted with the client’s key. The decrypted string contains a byte with value 4, the client’s challenge, a seven byte ticket key, and a fifteen byte ticket. The ticket is placed in the auth field of a subsequent attach message to validate a connection.
The ticket key is currently unused. It may one day be used to encrypt subsequent communication with the server.
These messages are also documented in the section of auth(6) describing the fsauth protocol.
If a server does not perform authentication, it should return an Rerror when it receives an auth.
ENTRY POINTS
Mount (see bind(2)) generates an auth transaction to the remote file server. When the kernel boots, an auth is made to the requested file server machine.
SEE ALSO
Plan 9 — January 03, 1993