Terminal Access

From unRAID
(Redirected from Telnet)
Jump to: navigation, search

Terminal Access

What is "Terminal access"?
It's the opening of a terminal session and obtaining a command line prompt, at which you can enter commands directly on the system, whether you are on the system itself using its keyboard and monitor, or on a different machine using SSH or Telnet. It's called by different things, such as a 'shell' or 'console' or 'terminal' or 'command window', but always is line driven and has a command prompt. It's very similar to an MS-DOS command prompt in Windows, a 'DOS box', except this is Linux, so you can't use DOS commands. Linux terminal sessions usually always require a login with password.
If you have a monitor attached to your unRAID server, then when you boot normally (not the boot GUI), you end up at the console with a login prompt. This console is a terminal session.
For terminal access from other machines, unRAID includes both Telnet and SSH support. Telnet is no longer recommended however, because it is older and easier to attack. SSH is recommended instead as more secure. There are instructions below for disabling Telnet, but Telnet does make it easier the first time you want to access your server from another machine. But please remember that it is more secure to disable Telnet, and set up SSH for all further terminal access.
Linux and Mac stations already have terminal access built in. For Windows, PuTTY is the recommended package, with enhanced support for both Telnet and SSH. Instructions and links in the PuTTY section below. Another recommendation, for Windows or Mac, is Xshell, similar to PuTTY.
Naturally, you should already have entered a password for 'root' on your unRAID server!
Note: this page assumes you are running unRAID v6. The Telnet sections should work for all versions of unRAID, but the SSH sections are only useful for systems with SSH installed and working. SSH is included and set up in v6, but it will only work with earlier versions if you install an SSH package.


SSH

unRAID v6 and later automatically sets up the SSH keys necessary for SSH access
For terminal access from a Windows station, use the PuTTY instructions below to install, configure, and set up the SSH connection
more help needed? ssh setup help? (WIP)


Telnet

Using Telnet
The unRAID Server software includes a built-in Telnet server, which may be used to open a command window (also called a shell or console) on your server. Access to this console is through a Telnet program from your desktop station. The Telnet tool is usually a part of most operating systems, and generally immediately available, but in Windows Vista and Windows 7 and probably later versions too, it needs to be 'turned on' through the "Turn Windows features on or off" tool. Please see this thread for comments on Telnet usage in Vista, Windows 7, and the Mac. Instead of the built-in Telnet tool, we recommend installing PuTTY, with enhanced Telnet services.
Disabling Telnet
Use Tips and Tweaks plugin to disable Telnet and FTP on your unRAID server
Or add these 2 lines to your go file, /boot/config/go (type them EXACTLY as below!)
sed -i -e 's/^telnet/#telnet/' /etc/inetd.conf
/etc/rc.d/rc.inetd restart
Note: see also this


PuTTY

Linux and Mac have their own built in terminal access programs, but Windows needs a little help. Windows does have a Telnet client, but it is a bare bones function, and usually hidden and needing to be turned on. For Windows, we strongly recommend the PuTTY program package. It's free and includes enhanced support for both Telnet and SSH. Unlike Windows Telnet, PuTTY allows you to use the mouse and advanced keys, such as the arrow and function keys. PuTTY can also be setup with your unRAID server name or IP and SSH host key.
Because PuTTY is just an enhanced Telnet and SSH program, it can be used instead of Windows Telnet anywhere that Telnet or SSH is mentioned, such as anywhere in the Wiki or the unRAID forums. It is used the same way as Windows Telnet, but because it supports the mouse and arrow and function keys, it is much easier to use in programs like MC (Midnight Commander, a dual pane commander-like file manager). For an example, see Transferring Files Within the unRAID Server.
Note for UnRAID v5 and v6 users: some have found that Midnight Commander looks funny, with accented letters (mostly a little 'a' with a hat) where line drawing characters should be. In your PuTTY configuration, go to Window->Translation and set Remote Character Set to something like UTF-8, then restart MC (thanks to Wody for this tip, see this). Wody has an additional PuTTY tip in this post.
PuTTY has a number of settings, but the defaults are usually fine. On the Window tab, I set Columns to 120, Rows to 60, and Lines of scrollback to 2000. On the Translate tab, I set Remote character set to UTF-8.
First time SSH connection: set Connection type to SSH, then enter your exact unRAID server name or IP (if static), then enter a Saved Session name (such as SSH Tower), then click the Save button. You are ready to click your session name and connect! When you do this the first time, you will be informed about the host key and whether you trust this server and want to cache its host key. Click Yes and the host key will be saved, and you won't be asked again. (This creates a secure connection that can't be spoofed.) Then a terminal session box will open up with a login prompt. Enter root and press <Enter>, then enter your password and the <Enter> key again. You are now in a Linux terminal session at a command prompt! Type exit to quit.
First time Telnet connection: set Connection type to Telnet, then enter your exact unRAID server name or IP (if static), then enter a Saved Session name (such as Telnet Tower), then click the Save button. You are ready to click your session name and connect! When you do, a Telnet terminal session box will open up with a login prompt. Enter root and press <Enter>, then enter your password and the <Enter> key again. You are now in a Linux terminal session at a command prompt! Type exit to quit.
On subsequent uses, just start PuTTY and click the session name you want to use, and you will immediately be at the login prompt.
Note: Xshell is a commercial alternative to PuTTY, similar and possibly more powerful, free for home use.


Opening a terminal session with the Windows Telnet tool

To open a Telnet session from Windows click Start -> Run. In the dialog box type:
telnet tower
If you renamed your server from tower, enter that name instead. Also, you may enter the server’s IP address instead of its name. A command window will open and you will be presented with a login prompt. The login name is root, and by default, there is no password. To terminate the session, just close the window. You may have multiple Telnet sessions to the same server. You can select/copy/paste the text from a Windows Telnet window by right-clicking the title bar. Notes regarding the command shell:
* commands and arguments are case-sensitive
* commands and arguments must be separated with spaces
* commands are executed after pressing the Enter key


Related links

SSH vs Telnet - discussion of the merits of both, why many want Telnet disabled
Google search of "how to secure your ssh server"
FAQ, How is a Linux console different from a Windows console?
FAQ, What commands can I use at the unRAID console?
Console - basics of console usage, plus commands for drives, networking, system management, files and folders, and system information
Introduction to the linux shell - helpful but needs updating for v6