Blocking ssh but not sftp/scp

I looked around and around and couldn't find a good answer for this.  I
tried something sneaky and it seems to have worked...I can't determine
why it works or if it has done something flaky with security...I was
wondering if anyone could tell me...

 I've added a few lines to the skeleton bash_profile:

if [ -f /bin/superchunk ]; then
  exit
fi

where /bin/superchunk is simply an empty file that exists and is
readable.
...or maybe is there an easier way of doing this? :)

Shane


Shane Ian Hoffman
Computer Services Librarian
Westerville Public Library

Phone:  614-882-7277 xt 114
Fax:    614-882-5962
E-Mail: shoffman@westervillelibrary.org