Changes

<!-- {{Admon/important|Backup Your Data|These computers are NEVER backed up. Please save all important files on other storage. '''These machines may fail, be removed , be upgraded, or be reinstalled at any time.'''}}In [[SPO600]], remote access to servers is provided for learning and project work. It is recommended that you also set up [[SPO600 Host Setup|a personal Linux system]].--> 

In order to gain access to these computers, you must send an [[SSH]] key to your [[User:Chris Tyler|professor]].<!-- Please follow these instructions exactly:

# Copy the public key (<code>id_rsa.pub</code> or <code>id_dsa.pub</code>) to a file named <code>''yourUserId''.pub</code> -- for example, if your Seneca chosen user ID is "jldoe", save the key in the file <code>jldoejdoe.pub</code> using a command such as: <code>cp ~/.ssh/id_rsa.pub ''jldoejdoe''.pub</code># Attach that file to an e-mail message and send it to [mailto:chris.tyler@senecacollege.ca chris.tyler@senecacollege.ca] including with the course code subject line "SPO600Key" somewhere in the subject line.-->

=== AArch64 ===<!--==== aarchie ====The first server {{Admon/important|Content being Updated|This page is an [[ARMv8]] AArch64 system known as '''aarchie''' or '''archie''in the process of being updated from a previous semester's content. This is The SPO600 servers will be set up in a system that new configuration later this semester, and this information will be updated. Do not rely on this information until this warning is currently located inside the [[EHL]]removed. To connect to this system, you }} {{Admon/important|Server Changes|The server configurations have changed several times -- previous mentions of these systems by name may have referred to go through different hardware. Note that servers may be added or removed as the EHL gateway on port 2200semester proceeds.}} -->

If you're using a command-line ssh system, and you The names of servers within CDOT are based on the Seneca network, you can issue a command such as this:names of countries. There is no significance to the country names.

ssh -p 2200 ''username''@ehl.internal=== AArch64: israel.cdot.systems===

To connect from outside SenecaA main AArch64 system is available, known as ''israel''. This machine has a lot of mid-range cores. You can access this system at the hostname israel.cdot.systems; if you're using a command-line ssh system, you can access aarchie with a command such as this:

ssh -p 2200 ''username''@ehlisrael.cdot.systems<!-->==== betty =AArch64: bbetty ===The current [[ARMv8]] Another type AArch64 server system is known available as '''betty''' (or '''bbetty'''). This machine has a moderate number of low-medium cores. This is a system that is currently located inside the [[EHL]]. To connect to this system, you need have to connect go through the EHL gateway on port 22012200.

If you're using a command-line ssh system, and you are on the Seneca network, you can issue a command such as this:

ssh -p 2201 2200 ''username''@ehl.internal.cdot.systems

Our x86_64 server is known as ssh -p 2205 '''xerxes'username''@ehl.This system is located outside the [[EHL]] but is accessed through the EHL gateway from outside Seneca, using port 2202cdot.systems

Or you A different AArch64 system is ''israel''. This machine has a good number of mid-level cores. This system is located outside of the EHL and can connect be reached directly:

ssh xerxes.internal''username''@israel.cdot.systems-->

To connect from outside Seneca=== x86_64:portugal.cdot.systems ===

ssh -p 2201 The x86_64 server system is known as ''usernameportugal''@ehl.cdot.systemsIf you're using a command-line ssh system, you can access xerxes with a command such as this:

If you're using OpenSSH (the ssh client used on most Linux systems and other platforms), you can simplify complex ssh command lines by placing host connection details in the file <code>~/.ssh/config</code>:

<!-- Host "bettyaarchie"

user "chrisYourUserID" port 22012200

Host "betty-internalbbetty" hostname "ehl.internalcdot.systems" user "YourUserID" port 2202 Host "ccharlie" hostname "ehl.cdot.systems" user "chrisYourUserID" port 22012205

user "chrisYourUserID" port 22022205--> Host "portugal" hostname "portugal.cdot.systems" user "YourUserID" Host "israel" hostname "israel.cdot.systems" user "YourUserID" <!-- Host "xerxes" hostname "xerxes.cdot.systems" user "YourUserID"--> Once you have added these lines (inserting your user ID where appropriate) and set the permission on that file (<code>chmod 0600 ~/.ssh/config</code>) you can use these commands to access the servers:  ssh israel

Host "xerxes-internal"ssh portugal  hostname "ehlYou can similarly configure simplified access in most other SSH client programs.internal  == Multiuser Access == Remember that these machines are multi-user systems.cdotUse the <code>w</code> or <code>who</code> commands to see who else is using them; you can also try using the <code>write</code> command to communicate with another user if required.systems" user "chris" port 2202

Or Your password on each of these commands systems has been set to a random string (different on each host). You can find out the original random password by viewing the file <code>~/password.txt</code> and you can change the password with the <code>passwd</code> command. Your password is used for sudo access betty and xerxes from inside Seneca:(see the next section).

{{Admon/caution|Do Not DO NOT Build or Install Software Except Via as Root except via RPM (dnf/yum) or DEB (apt)|Do not build or install software as the root user (using <code>sudo</code>), except in RPM or DEB form using the <code>dnf</code>/<code>yum</code> or <code>yumapt</code> commands(as appropriate to the system). Building or installing software as root may overwrite system files and be very difficult to track down.<br /><br />It is OK to install software into your own directories (e.g., <code>~/bin</code> or <code>~/local</code>), which can be done without root privilege.}} In order to use <code>sudo</code>, you will need to know your password. An initial random password is provided in the file <code>~/password.txt</code> (note that your password will be different on each server). Feel free to change this with the <code>passwd</code> command -- not by editing the file, which is provided only for your information!  == SSH Access from Other Client Systems == If you wish to access the servers from additional computers, you can append the SSH public keys from those computers to the <code>~/.ssh/authorized_keys</code> file. Alternately, you can copy the private key from one client system to another (e.g., your laptop to your desktop).  == OS Versions == The current servers are both running Fedora 35 and will be updated from time to time. The machines may not be updated at the same time, so the versions of software may vary slightly. The kernel versions may also vary between the systems because of kernel hardware support.

== Multiuser Access Backup Your Accounts == These accounts are ''never'' backed up, and the machines may fail, lose data, or be reinstalled without warning at any time. Please back up your work frequently by copying it to another system or storage device.  == Common SSH Problems == With the OpenSSH client:# Your ssh private key must be in your <code>~/.ssh</code> directory (which must have 0700 permission) and the private key file must have 0600 permissions -- no more and no less. # If your SSH public key is not named <code>~/.ssh/id_rsa</code>, your SSH client may not automatically find it. You can specify the identity (private key) file using the <code>-i</code> argument to the SSH command.}} ==== Debugging SSH Connection Problems ==== ===== Situation 1: The SSH client asks you for a passphrase ===== The passphrase is the one you provided when you created your SSH keys. You must remember this passphrase in order to successfully unlock your private key. If you do not remember your passphrase, you will need to create a new pair of keys and re-send the public key to your professor:# Create the keys with <code>ssh-keygen -t ed25591</code># Copy the public key (which by default will be named <code>~/.ssh/id_ed25519.pub</code>) to a file named <code>'''UserId'''.pub</code> where '''UserId''' is your Seneca User ID.# Attach that file to an e-mail message and send it to your professor. ===== Situation 2: The SSH client asks you for a password ===== The password is for the remote system, but the SSH client will only ask you for a password if it is unable to authenticate using your keys. If that is the case, then one of your keys is corrupted, missing, has the wrong permission, or can't be found by the SSH client.# If you're using OpenSSH, try using the <code>-i</code> argument to tell the client which private key identity file to use: <code>ssh -i /path/to/ssh/PrivateKey ...</code># Check the permissions on the private key and the directory holding the private key.# If necessary, generate a new key and send it to your professor (see the previous section). ===== Getting Verbose Output ===== To see what the OpenSSH client program is doing, you can use the <code>-v</code> (verbose) argument, up to three times: <code>ssh -vvv ...</code> By reading through the output carefully, you can see what the OpenSSH client program is doing, and address any problems that arise (such as permission or file naming issues). == Disconnect/Reconnect Ability == The [[Screen Tutorial|screen]] utility provides disconnect/reconnect capability, which is very useful for unstable network connections, long interactive operations, and changing your work location. Other programs such as tmux provide similar capability.

Remember that these machines are multi-user systems. Use the <code>w<For graphical disconnect/code> or <code>who</code> commands to see who else is reconnect capability, consider using them; you can also try using the <code>write</code> command to communicate with another user if requiredVNC.