On Sun, 02 Nov 2008 05:34:19 +1030, Tim wrote:
On Sat, 2008-11-01 at 18:08 +0000, Beartooth wrote:
> Oho! Then all those who said "get rid of telnet" really
> *meant* "get rid of telnet-server." Right?
Yes, but there's more to it than that. Having a telnet server is a
security risk. Using telnet over an open wire is a security risk (what
you type is not encrypted, so passwords can be snooped on, etc.).
So, do not use telnet where you don't have to. But it's certainly a
useful tool to try and connect to some server to see what it responds
with. You can connect to a webserver, etc., using the telnet client,
and what you do is no riskier than using a web browser. Just don't type
confidential stuff when not encrypted.
Aha : I used it only a little when I did use it (mainly just to
do remote email at a provider that ran linux); I had no idea it could
connect to any server but its own; knowing that helps a lot. Many thanks!
> So does that mean I should run "yum install
telnet" on all
> machines?
Only if you want to be able to use the telnet program on them to connect
to some server.
Then for the time being, I guess, it should suffice to have only
the client, only on the machine with the printer. It's installing now.
> With the server on none?
I wouldn't install a telnet server anywhere. You don't need it, as
you've got plenty of other better options for remote accessing a
machine, such as SSH. It's not like we don't have better options that
we're forced to make do with telnet.
It is a consolation not to be mistaken at all points, as Gandalf
says to Gimli in the eaves of Fangorn.
> What responds to "telnet 192.168.a.b 631" on a machine
with no telnet
> at all?
A telnet server listens on port 23, by default. And you could log in
and have a remote shell through it.
That must be what I did in the bad old W98 days, in order to be
able to run Pine on a linux machine, before I had linux at home. I
*think* I had a shell there; I certainly did in my last years working,
when I ran OS/2 on my workstation, but Pine on an AIX machine in the
basement.
Without that server, you can't do
*that*. But, you can use the telnet client to connect with other types
of servers (mail, HTTP, etc.), and those servers will be the thing that
responds. Some will be useable, some can't really be interacted with in
a useful manner.
CUPS being one of the useful ones; that's all I'm likely to try
for now, since I'm used to running ssh on the LAN at need.
If you telnet to port 631, it'll be the CUPS server that
responds, if it
can (CUPS has to be working, and allowing connections over the network
that you're trying to access it).
If I have a Firefox tab open to it, does that mean it's working?
I suppose, after the changes I made (yesterday, I think) to the Trusted
tab on the firewall, it should be.
> For that matter, what about "ssh 192.168.a.b 631"
instead? I am at
> least relatively familiar with ssh.
That's not going to work, as CUPS listening on port 631 won't know
anything about the SSL encryption that SSH uses, and there's a different
syntax for specifying non-default ports with SSH.
Telnet is little more than a remote terminal over a network.
Well, I made my living on one of those for years, cataloging
foreign language materials into a library. This may be easier than I was
beginning to expect. Many many thanks!
===== ===== =====
Oops! I just got this (edited slightly) :
[btth@Hbsk2 ~]$ telnet 192.168.a.b 631
Trying 192.168.a.b...
telnet: connect to address 192.168.a.b: No route to host
[btth@Hbsk2 ~]$
===== ===== =====
Fwiw, ssh from this machine to that one did work.
--
Beartooth Staffwright, PhD, Neo-Redneck Linux Convert
Remember I know precious little of what I am talking about.