RSH, SSH, RCP


TABLE OF CONTENTS
---------------------------------------------------------------------
## BACKGROUND
H1.	What is a shell?
H2.	rlogin (remote login)
H3.	SSH

## RSH
RS1.	Description
RS2.	Usage

## RCP
RC1.	Description
RC2.	Usage

## SSH
SH1.	Description
SH2.	Usage


BACKGROUND
---------------------------------------------------------------------
H1. What is a shell?
* An interface for users to interact with the machine/kernel
* Examples:  MS-DOS, bash, csh, etc...

H2. rlogin (remote login)
* A utility released as part of the BSD Unix operating system 1983.
* Allows users to log in to another host via a network
* Features the two utilities rsh (remote shell) and rcp (remote copy)
* Important security issues - sends all information, including
  passwords, unencrypted.  Thus, it is very insecure and is extremely
  vulnerable to malicious attacks over a network
* Typically configured to not ask for a password, due to an assumed
  trusted network
* Uses TCP port 514

H3. SSH
* Because rlogin is insecure over an untrusted network, SSH was
  created to replace it in 1995
* Uses a secure, encrypted channel for communication
* Authentication is done using public-key cryptography
* Typically uses TCP port 22
* Many implementations for Windows, Mac, and Unix


RSH
---------------------------------------------------------------------
RS1. Description
* Remote SHell
* Allows a user to execute shell commands as another user, and
  access another computer via a network (if an RSH server, rshd, is
  running).
* As a security measure, most machines do not, and should not, allow
  rsh connections from an untrusted network such as the Internet

RS2. Usage
* Example: Login to 'host.example.com' as user 'bob'

  > rsh -l bob host.example.com

* Example: Execute the 'date' command on 'host.example.com' as user
  'bob'

  > rsh -l bob host.example.com date

* Example: Append a remote file to the end of a local file

  > rsh host.example.com cat remotefile >> localfile

* Example: Append a remote file to the end of a remote file

  > rsh host.example.com cat remotefile ">>" other_remotefile

* (maybe show examples on Mimosa, logging into the compute nodes, etc)
* man rsh


RCP
---------------------------------------------------------------------
RC1. Description
* Remote CoPy
* Allows a user to copy one or more files from one machine to another

RC2. Usage
* Example: Copy 'file1' from the current directory on the local host
  to the '/home/user' directory on 'host2'

  > rcp file1 host2:/home/user

* Example: Copy 'file1' from the '/home/user' directory on 'host2' to
  the currect directory on the local host

  > rcp host2:/home/user file1

* Example: Working as different users 'bob' and 'jill'

  > rcp bob@host1:/home/bob/bobs_file jill@host2:/home/jill/bobs_file

* (examples)
* man rcp


SSH
---------------------------------------------------------------------
SH1. Description
* Secure SHell
* Allows data exchange over a secure, encrypted channel
* As in rsh, allows commands to be executed remotely
* Supports tunneling of TCP ports and X11 (GUI) connections
* Can transfer files using 'scp' or interactively with 'sftp'

SH2. Usage
* Example: Login to 'host.example.com' as user 'bob'

  > ssh bob@host.example.com

* Example: Run the 'date' command as user 'bob' on 'host.example.com'

  > ssh bob@host.example.com date

* Example: Copy local file 'file1' to 'host.example.com'

  > scp file1 bob@host.example.com:/home/bob/file1

* (examples)
* man ssh
* man scp
* man sftp