How to use one time passwords

At first sight the procedure seems a little complicated, but all in all there are only a few steps to do in the forefield; just look at the relevant in- and outputs.

First initialize this feature on the machine you will later connect to (sg2.dbai.tuwien.ac.at), and if prompted for a password, you can specify your common system password or any different one (ignore the warning, but if possible connect from inside DBAI): 


sg2.dbai% opiepasswd -f -c
Only use this method from the console; NEVER from remote. If you are using
telnet, xterm, or a dial-in, type ^C now or exit with no password.
Then run opiepasswd without the -c parameter.
Using MD5 to compute responses.
Enter new secret pass phrase: ***********
Again new secret pass phrase: ***********
ID user OTP key is 499 po0326
COLA AMMO LILY TINE AVON WALE


Then, with the above created seed 499 po0326, you can generate an arbitrary number of one time passwords (thirty in this example) and print these on paper; if you can't remember the seed, a test login to sg2 will show you (look at the end of this section): 


sg2.dbai% opiekey -n 30 <↑your seed from above>
Using the MD5 algorithm to compute response.
Reminder: Don't use opiekey from telnet or dial-in sessions.
Sorry, but you don't seem to be on the console or a secure terminal.
Warning: Continuing could disclose your secret pass phrase to an attacker!
Enter secret pass phrase: ***********

        :
        :
498: PAD BOSS WADE PHI FOSS FOIL
499: COLA AMMO LILY TINE AVON WALE



Now, if you want to login from an unsecure foreign machine, connect with ssh, abort the normal password login with ^D (Windows user please look at footnote [1]), and login with the one time password corresponding to the given iteration number (498) on your printed list: 


foreign% ssh -l <username> sg2.dbai.tuwien.ac.at
Password: ^D
otp-md5 498 po0326 ext
Response: PAD BOSS WADE PHI FOSS FOIL

sg2.dbai%
Voila, you now are logged in in the DBAI login server sg2.

Footnotes

[1] Windows user (at least when you use PuTTY): Instead of pressing ^D (which closes the window) you have to do this: