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Go forward to Authentication: The S/Key-card
One annoying side-effect of challenge/response authentication schemes
(or: one-time passwords) is lack of support in regular FTP
client programs. In order to be able to communicate directly to the
proxy-server, the user will be required to employ the quote
command in the FTP client program.
For example, if you are joe and you are abroad on
host foo.bar.com and want to connect with FTP
to sunshine.cs.uu.nl you might employ the proxy as follows:
foo.bar.com% ftp -n gatekeeper.cs.uu.nl
Connected to gatekeeper.cs.uu.nl.
ftp> quote auth joe
331 Skey Challenge "s/key 512 gz12345":
ftp> quote response FAT FEND DEFY FUEL LENS ORE
230 User authenticated to proxy
ftp> user joe@sunshine
331-(---GATEWAY CONNECTED TO sunshine---)
331-(220 sunshine FTP server (SunOS 5.6) ready.) ready.)
331 Password required for joe.
230 User joe logged in.