Why won't my linksys router pass telnet?

[TrogL]

I'm trying to set up a linux server on my side of the router and have telnet open to the world (it's relatively safe, there's one account with a 24 character password).

Anonymous ftp works fine, but telnet doesn't.

What gives?

[Occulus]

1. Remove the router first

to check if it's a problem with the router blocking the telnet requests. If it still doesn't work, even without the router, your server is likely configured incorrectly. If it does work without the router, then your router is likely blocking the port(s) that telnet is using. Maybe your server is set up to listen on a different port?

Having never set up a telnet or FTP server in linux, I might be totally off base with this.

[Atlant]

4. Things to try...

He can tell whether his telnetd is working simply by either
trying to telnet right back to himself or by pinging the telnet
port (port 23).

By default, most firewall routers block all incoming connects
so it's probably just the Linksys doing what it's supposed to
do by default.

Remember that you should be able to manage the Linksys
by accessing http://192.168.1.1/ from inside your Linksys's
firewall.

Atlant

http://www.iana.org/assignments/port-numbers

[Rabrrrrrr]

2. Are you sure it even swallowed telnet?

:evilgrin:

I don't have a good answer - I have no problem with using kazaa with my linksys, but can't share files over AIM or MSN PMer program thingy. Never been able to figure out why.

And the MSN thing was me and my partner trying to share files over our home network (though of course, the files still have to go through MSN).

[Ivory_Tower]

3. Does your router have a built-in firewall?

My linksys router has a firewall in it. If you've got the same thing, you might want to check the router's firewall configuration -- my guess is it's blocking telnet access and you'll just have to enable access.

[TrogL]

5. I enabled telnet and ftp on the router

I can telnet into the box at 192.168.1.101 from inside. I can ftp to its address inside and outside. I just can't telnet from outside.

My linux buddies are telling me I should be doing ssh anyway for security reasons, but I want to get telnet working first.

If it's a lost cause, maybe I should go ahead and try ssh.

Is there a good ssh windoze client? I know how to do the UNIX end.

[Atlant]

6. Are you sure you've set up the Telnet hole to target your Linux box?

(I have to admit that I haven't opened any holes in my Linksys's
firewall, so this is all theoretical for me.)

As I understand the Linksys setup, and assuming you're running
NAT so that you present one external IP address, then when you
open an incoming hole in the firewall, it must then target a specific
node inside the firewall (as otherwise, the router would have no idea
where to send the, say, Port 23 traffic that targeted the router's
external IP address).

So you do have the Port 23 Telnet traffic aimed at the Linux
system, right? Presumably, your FTP traffic is targeting the
same internal IP address/Linux system.

This is all set on the "Advanced" (Filters) page of the router
setup built-in web-site.

Atlant

[Ivory_Tower]

7. SSH client

At work we use "SSH Secure Shell Client" (www.ssh.com) but I don't think it's freeware (hey, my company paid for it, so I'm not complaining).

Your friends are right -- if you do get telnet working, get rid of it as soon as possible and switch to ssh.

I've never opened any holes in my firewall, either, but I think Atlant's post is probably right -- make sure you've opened the port for telnet and that you're directing that port's traffic to your linux box.

Good luck.

[Atlant]

8. I suppose this would be a bad time to mention... :-)

I suppose this would be a bad time to mention that a certain
operating system which isn't Windows and is disliked by Will
Pitt includes a full ssh implementation (server and client)
as a standard feature. :-)

Atlant

[Ivory_Tower]

11. I'm not asking anyone to bite anyone.

:)

So is the ssh implementation in the unmentionable OS an artifact of it running under BSD unix? I've been tempted to look at "the other side" but can't quite justify the expense yet.

[Atlant]

12. I think so.

I'm a Solaris guy, so I'm not intimate enough with BSD
to say for sure which bits come from BSD and which
come from NeXT, but I certainly assume that the
unmentionable O/S has its ssh implementation as a
result of BSD.

Ahh, wait a moment...

% strings /usr/bin/ssh | more

Reveals:

@(#)$OpenBSD: ssh.c,v 1.179 2002/06/12 01:09:52 markus Exp $

So I guess the answer is: Yup, BSD!

Atlant

[Nlighten1]

10. Putty

is the name of a good free windows ssh client.

[Nlighten1]

9. Why do you want to use telnet anyway?

If you are accessing local resources from the Internet using Telnet it isn't the safest way to do it.