How to set up a Telnet entry to WWW
A telnet serverA public telnet server allows anyone
to telnet to you and run a WWW client
program to get at data. We run one
We assume here you know what you
are doing and so here are a few points
to remember in outline only.
- Beware of secuity holes at all times.
- Make a special unpriviliged user
- You can set www up as the user's
- Run www with the -h option to turn
off recursive telnet hopping for
secuity. Also turns off shell escape,
pipe, file save, etc.
- We use a special /bin/login command
which obviates the need for a shell,
a no-password user, and for username
or password prompts. Available on
- Please mail email@example.com
to get your server added to the list
of tenet access points to the web.
It is useful to have a complete
list of these so people can log onto
the nearest one when away from home,
to cut network usage.
Skipping the shellThe special /bin/login program is
like login but if the guy has not
telnetted in with a command line
user name which matches one on the
host, he is thrown into www directly
without using a shell or collecting
$200. This means that if he find
some way to crash www, he is bound
to exit rather than accidentally
get a shell.
The login_www program which replaces
login passes a -h ip.ip.ip.ip option
to www which tells www where the
call is coming from (www logs all
transactions and also login_www logs
the session for safety).
This makes the machine difficult
to acces for normal purposes especially
if rlogin is disabled for security
reasons too. Only some machines
(Ultrix, NeXT, ...) support telnet
-l username which is necessary to
Changes in browser behaviourWhen www gets the -h option it behaves
differently, mainly for secuity.
(The HTSecure flag is set within
- It disallows any telnet hopping --
you can't use a public www server
to "launder" your telnet access for
hacking by telnetting on to some
other site. (See HTTelnet.c)
- It disallows shell spawning, printing,
saving files etc etc. . It also
requires a full "quit" rather than
just "q" to exit. (HTBrowse.c)
- It uses a different home page, see
- It logs all access by default.
Home pageWhen www is used with the -h option,
the home page is set by the WWW_HOME
environment variable as usual. If
you are using the special ligin program,
then there is no shell script in
which to set this. The browser therefore
checks, is WWW_HOME is not set, for
a file /etc/www-remote.url. If that
file exits, it reads from it the
URL of the home page. Note that
the home page cannot be a local file,
as local file access is turned off
for security reasons. It must be
a document availableon the network,
from your own or someone else's server.