Changes
→Troubleshooting
This page is intended Provides a summary of basic SSH usage on acidburn, with notes for [[ECE2524]] ECE 2524 students as well. In the future, these will be separated into two pages.One advantage of a shell account is that it allows one to leave an IRC client constantly connected, eliminate join/quit spam, and others new log missed messages to check later. In order to accomplish this, the concept of console-based IRC clientsclient must be run inside either [[tmux]] or [[screen]] so thatit will not be killed when you disconnect from SSH.
== CVL SSH accounts ==The [[gp:Bradley Department of Electrical and Computer Engineering|ECE]] department offers shell ccounts on the [[gp:CAD and Visualization Laboratory|CVL]] for Virginia Tech affiliates. Accounts can be created at [http://computing.ece.vt.edu/accounts/ this page].
The ECE2524 VM (128.173.88.125) can be accessed via SSH for CVL users, and has tmux, mosh, and weechat installed. Acidburn The[[gp:CAD and Visualization Laboratory|CVL]] is also useful for general computing (acidburne.vtluugg.org[[MATLAB]]), the VTLUUG shell server, has a few more IRC clients installed, as well as other software and full IPv6 support.
Here's the procedure for using either the ECE2524 server or acidburn for IRC:
#* For acidburn, come to a meeting and request an account
# Connect to the remote machine via SSH
#* <code>ssh 128pid@ece2524.173ece.88vt.125edu</code> for the ECE2524 server(with your actual PID)#* <code>ssh user@acidburn.vtluug.org</code> for acidburn
# Begin a tmux session to allow your console to persist between logins
#* <code>user@ece2524:~$ tmux</code>
# Now detach from the tmux session to return to a terminal while leaving weechat running
#* <code>^b-d</code> (that is, press Control-b, then d)
#* ''Use this whenever you are inside a tmux window and wish to return to a shell''# To, reattach to the first tmux seesion, just use <code>tmux aattach</code>#* <code>user@ece2524:~$ tmux attach-d</code>. #* ''On subsequent logins, this should be the only command you need to execute to return to IRC'' '''If you have been given a temporary password please reset it by running<code>$ passwd</code>''' ==Other SSH Suggestions==* Use [https://wiki.archlinux.org/index.php/SSH_keys SSH Keys]* Write up your own [[tmux|tmux.conf]]* Use X-forwarding on servers that support it: <code>$ ssh -X user@client.server.tld </code>* Check out the [http://www.dayid.org/os/notes/tm.html tmux and screen cheat sheet] for a quick reference of some of the other tmux commands. An additional command that might be useful is <code>tmux list-sessions</code>.*[http://mosh.mit.edu Mosh] is another helpful tool you may want to use for high-latency or mobile (e.g. wifi) connections. You also may want to look into zsh, an alternative to bash with more features.*You also may want to setup an [http://nerderati.com/2011/03/simplify-your-life-with-an-ssh-config-file/ SSH config file] for host aliases and Kerberos authentication. ==Random Bash tips==* Tab completion exists on lots of things in your shell. For example, try "cd /" and then "cd /home/<TAB>" and it will autocomplete. It also exists in weechat for users' nicks. * Man pages are a helpful way to get usage information on commands. For example, run "man mv" in a terminal for usage information on mv. You can use PgUp/PgDn to scroll. Inside a man page, you can search using the "/" key. For example, to search "mv" for "existing file", type "/existing file" and hit enter to highlight all occurances and jump to the first one.* Inside a terminal, the up and down arrows can be used to recall the previous and next commands respectively, to prevent retyping long commands if you make a mistake.* Ctrl-D is the universal "end-of-file" command, and can be used to logout of shells* Ctrl-C is the universal interrupt command, and can be used to kill running terminal jobs and clear your currently-typed command (rather than holding down backspace).* Ctrl-Z can be used to pause processes, then fg or bg can be used to restart it in the foreground or background, respectively ==Troubleshooting==If you get an error like "ssh_exchange_identification: Connection closed by remote host", a few things are likely:* Your username/password combination is incorrect* You (or someone using your IP address) have had too many failed login attempts, and fail2ban or a similar utility has banned you for a period of time, typically a week or so. ** This is easy to identify because ssh fails ''before'' you are prompted for a password.** If this happened on a CVL machine, try connecting to a different node like <code>$ ssh pid@cvl10.ece.vt.edu</code> == See Also == * [[WeeChat]]* [[Irssi]] ==External Links==* [https://blogs.lt.vt.edu/ece2524s13/exercises/week-2-welcome-to-the-shell/#fnref1 Week 2: Welcome to the Shell (from ECE2524 blog)]* [http://linuxcommand.org/learning_the_shell.php Learning the Shell - Basic shell commands tutorial]* [http://linuxtutorial.todolistme.net Comprehensive Beginners Linux Tutorial]