166 lines
3.6 KiB
Groff
166 lines
3.6 KiB
Groff
.\" $NetBSD: skey.1,v 1.23 2017/07/03 21:34:21 wiz Exp $
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.\"
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.\" from: @(#)skey.1 1.1 10/28/93
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.\"
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.Dd July 25, 2001
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.Dt SKEY 1
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.Os
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.Sh NAME
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.Nm skey
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.Nd respond to an OTP challenge
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.Sh SYNOPSIS
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.Nm
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.Op Fl n Ar count
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.Op Fl p Ar password
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.Op Fl t Ar hash
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.Op Fl x
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.Ar sequence#
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.Op /
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.Ar key
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.Sh DESCRIPTION
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.Em S/Key
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is a One Time Password (OTP) authentication system.
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It is intended to be used when the communication channel between
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a user and host is not secure (e.g. not encrypted or hardwired).
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Since each password is used only once, even if it is "seen" by a
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hostile third party, it cannot be used again to gain access to the host.
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.Pp
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.Em S/Key
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uses 64 bits of information, transformed by the
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.Tn MD4
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algorithm into 6 English words.
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The user supplies the words to authenticate himself to programs like
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.Xr login 1
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or
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.Xr ftpd 8 .
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.Pp
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Example use of the
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.Em S/Key
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program
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.Nm :
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.Bd -literal -offset indent
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% skey 99 th91334
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Enter password: <your secret password is entered here>
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OMEN US HORN OMIT BACK AHOY
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%
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.Ed
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.Pp
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The string that is given back by
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.Nm
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can then be used to log into a system.
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.Pp
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The programs that are part of the
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.Em S/Key
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system are:
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.Bl -tag -width skeyauditxxx
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.It Xr skeyinit 1
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used to set up your
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.Em S/Key .
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.It Nm
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used to get the one time password(s).
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.It Xr skeyinfo 1
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used to initialize the
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.Em S/Key
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database for the specified user.
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It also tells the user what the next challenge will be.
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.It Xr skeyaudit 1
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used to inform users that they will soon have to rerun
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.Xr skeyinit 1 .
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.El
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.Pp
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When you run
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.Xr skeyinit 1
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you inform the system of your
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secret password.
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Running
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.Nm
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then generates the
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one-time password(s), after requiring your secret password.
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If however, you misspell your secret password that you have given to
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.Xr skeyinit 1
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while running
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.Nm
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you will get a list of passwords
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that will not work, and no indication about the problem.
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.Pp
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Password sequence numbers count backward from 99.
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You can enter the passwords using small letters, even though
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.Nm
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prints them capitalized.
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.Pp
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The
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.Fl n Ar count
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argument asks for
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.Ar count
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password sequences to be printed out ending with the requested
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sequence number.
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.Pp
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The hash algorithm is selected using the
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.Fl t Ar hash
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option, possible choices here are md4, md5 or sha1.
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.Pp
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The
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.Fl p Ar password
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allows the user to specify the
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.Em S/Key
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password on the command line.
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.Pp
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To output the S/Key list in hexadecimal instead of words,
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use the
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.Fl x
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option.
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.Sh EXAMPLES
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Initialize generation of one time passwords:
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.Bd -literal -offset indent
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host% skeyinit
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Password: <normal login password>
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[Adding username]
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Enter secret password: <new secret password>
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Again secret password: <new secret password again>
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ID username s/key is 99 host12345
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Next login password: SOME SIX WORDS THAT WERE COMPUTED
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.Ed
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.Pp
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Produce a list of one time passwords to take with to a conference:
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.Bd -literal -offset indent
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host% skey -n 3 99 host12345
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Enter secret password: <secret password as used with skeyinit>
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97: NOSE FOOT RUSH FEAR GREY JUST
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98: YAWN LEO DEED BIND WACK BRAE
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99: SOME SIX WORDS THAT WERE COMPUTED
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.Ed
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.Pp
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Logging in to a host where
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.Nm
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is installed:
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.Bd -literal -offset indent
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host% telnet host
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login: <username>
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Password [s/key 97 host12345]:
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.Ed
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.Pp
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Note that the user can use either his/her
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.Em S/Key
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password at the prompt but also the normal one unless the
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.Fl s
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flag is given to
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.Xr login 1 .
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.Sh SEE ALSO
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.Xr login 1 ,
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.Xr skeyaudit 1 ,
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.Xr skeyinfo 1 ,
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.Xr skeyinit 1 ,
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.Xr ftpd 8
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.Pp
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.Em RFC 2289
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.Sh TRADEMARKS AND PATENTS
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.Em S/Key
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is a trademark of
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.Tn Bellcore .
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.Sh AUTHORS
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.An Phil Karn
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.An Neil M. Haller
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.An John S. Walden
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.An Scott Chasin
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