File Transferring

A couple of days ago I wanted to transfer some source files on Archie (CDOT's ARMv8 - AArch64 system) and Xerxes (CDOT's x86_64 system) machines and run my program and analyze the result between these systems. When I regularly connect to these systems it uses my private key generated on my Linux machine as password and provides me access to Archie and Xerxes systems. I was having problems making a file transfer to these systems but after some research and help from professor (Chris Tyler) I learn few more interesting things as well.

Transferring file to Xerxes system was easy, If I’m on College’s network then I can just use “scp test.cpp (filename) (username)@xerxes.internal.cdot.systems:(destination)”. Xerxes server is only access able from Seneca’s network so, if you want to connect to Xerxes server from outside you can use other system which can be access able from outside like Archie and Matrix and using that you can connect to Xerxes system but you have to transfer the private key to these systems. Also after connection name if you do not include “: (destination)” the file will not be transferred it will just make copy of that file and put it in current directory with connection name as file name.

When you want to transfer file on Archie machine it’s little complicated because you have to specify the port number. Archie machine connection is set up to connect via different system so you have to connect to it using “ssh –p 2200 (connection name)”. Also for Archie there are two different connection names, one for connecting from outside College network (ehl.cdot.systems) and another for connecting from within Seneca network (ehl.internal.cdot.systems). so if you want to transfer file on Archie system you can use “scp –P 2200 test.cpp (filename) (username)@(connection name either internal or external):(destination)”. Also keep in mind that because Linux is case sensitive the scp command uses capital ‘P’ to specify port number.

If you have your private key protected by a passphrase and every time you want to connect to different machines you use your private key and you have enter your passphrase to unlock private key. If you use ssh-agent and add your private key to that agent and by doing that you can connect to multiple servers without entering your passphrase and also keeping you private key secured at the same time. You can do that by entering command “eval $(ssh-agent)” the add your private key by entering “ssh-add ~/.ssh/id_rsa (path to private key)” and you will be prompt to enter your passphrase and enjoy.

Finally, there are many other services you can use to transfer files like: ftp, sftp, filezilla (GUI), wget, and more.