Where did they go?

[Chris Vail]

I've inherited what appears to be a fresh install of RH9.0. I know very little Linux, but have to learn in a hurry. I could not telnet to the system, and found out that telnetd (in /usr/sbin) isn't there. Neither is the korn shell. Are these in a package I need to install? Which package, and where do I start?


Chris

[Bruce Copeland]

Most default installations of recent Red Hat distributions have a lot of things turned off for security reasons. That's certainly the case for telnet and a number of other very insecure access services. If you're certain you understand the security implications, you can turn on telnet using the System Settings/Server Settings/Services from the Gnome menu or using chkconfig etc from the command line.

The korn shell is a different matter. Most linux users prefer bash (Bourne again shell) probably for historical reasons. You can make the korn shell your default. You need to have the pdksh package installed, and then you enable it as your shell from the Sytem Settings/Users and Groups management tool.

Bruce

[Chris Vail]

Bruce: telnetd isn't turned off: it is missing. I ran chkconfig --add telnet. At least now I don't get a "connection refused", it just times out. telnetd is still missing from /usr/sbin.


Chris

[Stuart Browne]

rpm -q telnet-server

If that fails, you need to install it from your installation media (or download it from RH).

Once it's installed (rpm -ivh telnet-server*.rpm), then you can chkconfig again, and make sure the firewall will allow your connections.

[Bruce Copeland]

Chris:

Stuart's right about checking for the telnet-server package. But regardless, you won't find /usr/sbin/telnetd. On my system (and presumably every other RH9), it's called in.telnetd.

Bruce

[Martin P.J. Zinser]

Hello Chris,

and just to re-iterate a number of recent threads around here:

- Try to avoid opening telnet in general and especially for root. Passwords are transmitted unencrypted and can easily be intercepted using a network sniffer.

- If you have to allow direct root login try to use ssh so that the communication is at least sent encrypted over the wire.

- Allowing root access via either telnet/ssh over the net is a risk since it gives an attaker a know account to try to break in to.

All the best,

Martin

P.S. A vist to your nearest bookstore might be a good idea. There are a number of books specifically about Redhat on the market.
P.P.S. I say that because I myself find reading a structured book is esp. helpful if you are approaching a new topic. No insult intended at all!

[Bruce Copeland]

Chris:

Along the lines suggested by Martin, the Red Hat documentation at

http://www.redhat.com/docs/manuals/linux/

is also pretty good--particularly the security and system administration manuals.

Bruce

[Steven E. Protter · Accepted solution]

Chris,

The things you excpect on HP-UX are on different locations.

By default Linux is more secure than a default HP-UX install.

To enable telnet:

cd /etc/xinetd.d

vi telnet or telnetd (all my boxes are ES 3.0 now).

Change the line that says disable = yes to disable = no

service xinetd restart

the xinetd.d directory is like the inetd.conf file in HP-UX.

There are solutions to almost any problem here.

Also, I'd recommend the series of books called "The Linux Bible" It contains cookbooks and the answers to most common problems.

To actually get telnet into the system if its really missing, put the original distribution CD's in the drive, and from the GUI fire up the gnome installer, it can be pointed at the cd and can install the telnet server.

My first hands on with Linux was less than 2 years ago. I'm getting pretty slick if I say so myself.

You can skip telnet and use your great secure shell cookbook. It works fine on Linux, no changes.

rpm -q telentd
rpm -q openssh

If its there, you don't need to install the binaries.

Have fun. See if you can figure out how to use lvm and Red Hat Mirroring and let me know huh?

Welcome to Penguinland.

It's nice.

SEP

[Stuart Browne]

Come on.. LVM is easy, and Software RAID isn't far behind :P But be serious.. use Hardware RAID :P

In any case, SEP, you need to learn RH's 'chkconfig' tool :P Too cool to be ignored *nod*, even if it is just a simple thing ;)

[Alexander Chuzhoy]

the telnet server executable is /usr/sbin/in.telnetd
to enable the telnet server.
Simply run
chkconfig telnet on

or you can edit the /etc/xinetd.d/telnet file and to change the line disable=yes to disable =no
then you have to restart the xinetd service...
service xinetd restart
Regards.

[Thomas Bianco]

I know this has been mentioned before; telnet is largely insecure, even for internal use only. OpenSSH is installed by default, and packages are available for almost every OS.

Something that hasn't been mentioned: XinetD (and it's little cousin InetD) are both insecure and needless memory hogs. if you can live without the trivial services the -INETDs provide, you'll be much happier.

[Chris Vail]

Stuart:
I ran your command, and got a message back showing version number,so I assume that the daemon(s) are installed.
Bruce:
Like a true unix geek, I ran a "man telnetd", and it gave me a response. Also like a true unix geek, I ignored the first section where the proper name is stated) and went right to the arguments and flags. I particularly like the comment "The source code is incomprehensible". That kind of honesty would get somebody fired in most IT shops, but is refreshing to find, even if only in the Open Source world.
Martin & Thomas:
I am a lot more cognizant of security issues than I wish I was, but this is a circumstance where security is a bad thing, not a good one--the root password is "password". I work for a computer hardware manufacturer, and this lab is where new systems are tested for interoperability. So secure shell AND telnet AND rlogin have to be tested, along with CDE and anything else I can think of. These machines will all be flattened and
rebuilt every few days, so any time spent on security is, yeah verily, wasted and there is so little of this which we are alloted on this spinning bluish orb.
SEP:
As usual, dude, you're awesome. Yeah, the telnet entry in the /etc/inet.d directory was "yes". This fixed it. I also noticed that the /etc/hosts had the hostname on the same line as localhost. I changed that, and now something else will probably break, but WTH? Its now working.
My Linux Bible arrived from Amazon this morning (along with my HP-UX Partitions book), so I'm building my library up. I should own stock in O'Reilly to get some of my money back.
Stuart (again):
I wish I could tell you what we're working on here, but it does have something to do with disk storage. The Open Source community will be on it like a duck on a junebug--if I can talk the boss into releasing enough data so that the community can adopt it. Hint: REALLY REALLY REALLY cheap SANs.


Chris

[Stuart Browne]

*grin* sweet ;)