Very Computer

---

John C. Wingenbach                 Martin Marietta Energy Systems
                                   Data Systems Research & Development

(615) 574-8345                     1099 Commerce Park
(615) 574-0792 (FAX)               Oak Ridge, TN  37830

Quote:>I am using tcpwrappers to provide a little extra security on my systems and have
>received a request to also provide a banner message prior to login.  I modified
>the wrappers program to print the contents of a file to stderr and it works great
>for telnet.  However, others (FTP, rlogin,...) croak.  Does anyone have any clues
>how I can make this work?  Or accomplish the same via another method?

        220-some text here\r\n
        220-some more text\r\n

In case of rlogind you will have to echo a null byte to stdout before
sending any text, or the client/server handshake gets messed up.

        Wietse

: I am using tcpwrappers to provide a little extra security on my systems
: and have received a request to also provide a banner message prior to
: login.  I modified the wrappers program to print the contents of a file to
: stderr and it works great for telnet.  However, others (FTP, rlogin,...)
: croak.  Does anyone have any clues how I can make this work?  Or
: accomplish the same via another method?

Its best to do this sort of thing at the protocol level not at the raw socket
level otherwise you can really*the higher level protocol up. Especially
for things that might use a binary protocol (rlogin will*up since you
won't have the inital NUL).

For things that create a standard login (such as telnet and rlogin) if your
UNIX supports it try creating a /etc/issue file for login to display (this
works with the standard Linux login and the shadow login package). You should
also be able to find a way to get your ftp demon to display an intro, check
your manual pages.

--
Brian Blackmore.