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SSH & Telnet for Your Web Hosting Account
SSH & Telnet for Your Web Hosting Account
Did you know that you can access web hosting servers remotely? How? By using either the SSH or Telnet protocols.
SSH (Secure Shell or Secure Socket Shell) is a Unix-based command interface and protocol developed by SSH Communications Security Ltd. used to remotely, and securely access the Web and other kinds of servers. It is actually a suite of three utilities – slogin, ssh, and scp – that are secure versions of the earlier UNIX utilities, rlogin, rsh, and rcp.
SSH allows you to
- log into another computer over a network
- execute commands in a remote machine, and
- move files from one machine to another
It provides strong authentication, secure communications over unsecure channels, secure X connections and secure forwarding of arbitrary TCP connections. It protects normally insecure protocols such as IMAP, allows secure passage through firewalls, and offers support for external authentication methods, including Kerbero/s and SecurID secure file transfers
In SSH, both ends of the client/server connection are authenticated using a digital certificate, and passwords are protected using RSA public key cryptography. Encryption algorithms include Blowfish, DES, and IDEA (the default). SSH2, the latest version, is a proposed set of standards from the Internet Engineering Task Force (IETF). A free version of the protocol, OpenSSH, is also available and used by many people.
SSH protects a network from attacks such as IP spoofing, IP source routing, and DNS spoofing. If an attacker managed to take over a network, he can only force ssh to disconnect and won’t be able play back the traffic or hijack the connection when encryption is enabled. It is available for Windows, Unix, Macintosh, and OS/2, and also works with RSA authentication.
The gsp.com site offers a list of SSH clients available off the Internet.
Telnet on the hand is a user command and an underlying TCP/IP protocol for accessing remote computers. Anyone who needs to use specific applications or data located at a particular host computer can use it.
The program runs on your computer and connects your PC to a server on the network. When you enter commands through the Telnet program, they will be executed as if you were entering them directly on the server console, enabling you to control it and communicate with other servers on the network.
A Telnet command request looks like this : telnet the.libraryat.whatis.edu, (computer name is made-up) and will result in an invitation to log on with a userid and a prompt for a password. If accepted, you would be logged on like any user who used this computer every day.
Most often, you are telneting to a Unix/Linux based system. Therefore, the commands you use such as “ls, cd, pine, elm, talk, rm” are Linux/Unix commands, and NOT telnet commands.
Windows 95/NT operating systems are shipped with a Telnet client included (found at “c:\windows\telnet.exe” and “c:\winnt\system32\telnet.exe” respectively) and Unix users can use the built-in Telnet client software shipped with the operating system.8
So, do you actually need your web host to provide access to either?
If you’re a novice webmaster or do not know UNIX commands, Telnet or SSH may not be right for you. Just use the control panel provided by your web host instead. If you can use either though, SSH is recommended to provide security for your password and data.9
The following forums also offer additional guidance.
- Web hosts don’t provide it because:
- Telnet not secure
- SSH is secure for user but allows direct access to file system. This requires the host to maintain a complex permission hierarchy to keep the system safe and sound
- If you really need it, you can ask your host to install it for you
- You can set up SSHD by specifying range of IPs allowed
- They can be used to transfer files from one server to another quickly
- Shell access is great for checking email, sorting email for spammassin and bayes filters, debugging scripts, etc.
- Not recommended for hosts to offer SSH access if users can view other users’ html files, php files, or perl files
- Telnet can be used for proxy lynx browsing
- SSH has the functionalities of Telnet but is more secure
- You can use an SSH-based FTP client on the SSH port (for simpler configuration and more security)