Networking Simplified - Part 09

Welcome to my ninth edition to my series “Networking Simplified.” In this tutorial, I will go over many clients to be used to talk to your computer locally, and what they are used for specifically, advantages etc.

SSHd – the Secure Shell, or even occasionally it is referred to as the Secure Socket Shell since it does, operate with sockets hehe daemon. SSHd is a unix based remote host controller that allows you to enter your or someone elses computer upon authentication.
SSH runs on the port 22 normally, so if you are wanting to use ssh make sure you have that port open on your firewall!
SSHd is a great tool for network administrators of all sorts, including web administrators, not only just personal LAN admins. SSH is actually an integration of the following tools: rlogin, ssh, and scp, in which those were developed from other early forms of remote host connection daemons.
SSH supports many types of encryption including DES, Blowfish, and IDEA (Default encryption algorithm, no not what the acronym stands for.
A common sshd command in the unix environment would be ssh – l username xxx.xxx.xxx.xxx
You can read more about sshd at http://www2.yo-linux.com/cgi-bin/man.cgi?topic=sshd which is the man page and some more details.

Telnet – Yet another remote login tool, however this one is not near as powerful, but much more widely used. Mainly because the world of computers is centered around the windows environments and Microsoft sadly chose to implement telnetd from unix, and ssh hadn’t been out yet. Telnet is not a favourite of mine, but if you plan on using windows you may have to use this quite often. Basic commands are C:\> telnet >> open xxx.xxx.xxx.xxx 23 < - being the default port.

rlogin >> rlogin is a simple host connection tool that is used in the unix environment. It is not however very powerful, and I do not recommend its use. But for simple connections you can still use it, and its good to give people you don’t always trust with full access, but trust with a shell account access because of its usability. One good thing about rlogin is that it can only connect to unix boxes and it uses a file called .rhosts that saves the password you normally use, and you can login without typing in that passord, a nice quick and easy tool to sue.

For you windows users that need ssh access to a unix box, a program that I recommend named Putty, can be downloaded from this site -> www.chiark.greenend.org.uk/~sgtatham/ putty/download.html

These login utilities provide administrators with the access of using computer’s without monitors. For instance, server boxes, an admin can access computers and use them without actually having to spend the funds to buy a new monitor, keyboard, video card, sound card, etc etc just because of the ability provided by remote login daemons and utilities.

These utilities are really all that is used, except for a few exceptions on other environments or on less popular operating systems. For instance HP UX uses different login utilities because of the compatibility issue. Some other unix’s provide loads and loads of tools that aren’t widely used, but renowned and accepted by administrators and common end users alike.

Hope you enjoyed this tutorial, please send all feedback to [email protected]

Umm. This tutorial has some incorrect information.

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SSH is actually an integration of the following tools: rlogin, ssh, and scp, in which those were developed from other early forms of remote host connection daemons.

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Last time I checked SSH did not come with rlogin.

In fact, rlogin and .rhosts are discouraged. Never should your users login without a proper username/password combination. It keeps track of users and avoids the "untrackable" guest.

You did miss that SSH often -- althought I believe it depends on the version -- includes sftp. Which is a nice alternative to regular FTP.

Yes, SSH was made from rlogin, ssh, and scp. It was made from those ideas. ie integration.

ftp wasnt the scope of the tut

and rlogin is great for a lan

Ah.. Ok.. Now I understand where you are coming from. scp is integrated with SSH but rlogin isn't. SSH is decendent of rlogin. Perhaps that's a better term. The whole r-commands are ancestors of SSH-1 (SSH The Secure Shell: The Definitive Guide by Barrett. Publisher: O'Reilly. First Edition. 2001) but I do not think they were "integrated" with SSH. I am curious as to why you didn't make the distinction between SSH-1 and SSH-2.

Integration -- to me anyways -- usually means "combined with" or "included". That's why I didn't understand why rlogin would be included with the SSH.

I still wouldn't use rlogin for a lan. There are still 30% of all attacks done internally. I'd still want to know what my users are doing. But that's me.

Great tutorial, as usual.

SSH is slowly phasing out TELNET because it's more secure in virtually all aspects. It encrypts the data (password) whereas TELNET doesn't.

I don't know about the other disitrubutions, but it's evident in Red Hat Linux. They have disabled the TELNET service by default.

Putty is by far the best SSH client out there.

id have to agree with you and thanks for the complement, however, Putty is a good client yes, but for windows only. ssh on unix is by far the best ssh client out there in retrospect :)