Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Key Applications and Application Protocols
           9  TCP/IP Interactive and Remote Application Protocols
                9  Berkeley Remote ("r") Commands

Previous Topic/Section
Berkeley Remote ("r") Commands
Previous Page
Pages in Current Topic/Section
1
2
Next Page
Berkeley Remote Shell (rsh)
Next Topic/Section

Berkeley Remote Login (rlogin)
(Page 1 of 2)

The “head” of the Berkeley remote protocol family is the remote login command, rlogin. As the name clearly implies, the purpose of this program is to allow a user on a UNIX host to log in to another host over a TCP/IP internetwork. Since Telnet is also often used for remote login, rlogin and Telnet are sometimes considered alternatives to each other for TCP/IP remote login. While they can be used in a very similar way, however, they are quite different in a few respects.

From a conceptual standpoint, Telnet is designed as a protocol to enable terminal/host communication. As I mentioned in the Telnet overview topic, the protocol was not designed specifically for the purpose of remote login. In contrast, rlogin was intended for that specific purpose, and this is reflected in its operation.

rlogin Operation

The protocol requires rlogin server software to be running on the host that is going to allow remote access; it is usually called rlogind (for rlogin daemon, the latter word being the standard UNIX term for a background server process). The server listens for incoming connection requests on TCP port 513. A user who wants to remotely log in to the server runs the rlogin command on his or her local host, and specifies the name of the server. The client makes a TCP connection to the server, and then sends to the server a string containing the following information:

  • The login name of the user on the client machine.

  • The login name that the user wants to use on the server (which is often the same as the user’s login name on the client, but not always.)

  • Control information such as the type and speed of the terminal.

The server processes this information and begins the login process. It will normally prompt the user for a password to log in to the remote host. Assuming the password is correct, the user will be logged in to the remote host and can use it as if he or she were locally connected.

Comparing rlogin to Telnet

From a practical standpoint, the rlogin command is much simpler than Telnet; it does not support Telnet’s full command structure, nor capabilities such as option negotiation. It does include a small set of commands, however. The client is able to send to the server one key piece of information: the current size of the terminal window in use. The server is able to tell the client to turn on or off flow control, request that the client send it the current window size, or flush pending output that the server has sent, up to a certain point in the data stream.


Previous Topic/Section
Berkeley Remote ("r") Commands
Previous Page
Pages in Current Topic/Section
1
2
Next Page
Berkeley Remote Shell (rsh)
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.