Difference between revisions of "Using ssh"
Revision as of 16:25, 15 November 2019
Using ssh to Access Math Department Resources
The University of Wisconsin-Madison Department of Mathematics maintains two login servers for ssh connections from outside the department.
- login0.math.wisc.edu: To connect to this server, you must have an IP address that corresponds to a wisc.edu host address. You can use the campus wireless or a VPN client to get a wisc.edu IP address. Other names for this server are bing.math.wisc.edu and login.math.wisc.edu. Any of these names should work.
- login1.math.wisc.edu. To connect to this server, you must use an ssh key. For instructions on using an ssh key, see below. Another name for this server is abel.math.wisc.edu.
To access Math Department resources via ssh, you must first use an ssh client to connect to either login0 or login1. You can then ssh to the system of your choice within the department.
For example, suppose you wished to run a sage program on one of the research servers. For simplicity sake, the research servers have aliases (nicknames) magma0, magma1, ..., magma19, with the more powerful machines having the lowest numbers.
To start your sage program, you might use an ssh client on your laptop to connect to login0.math.wisc.edu then run ssh again on login0 to connect to magma0. Please do not run research programs on login0 or login1. While these machines may have all the tools necessary to test programs, they are not powerful enough to handle more than the most trivial of tasks. If you run a program that uses a lot of resources on login0 or login1, you may prevent users (including yourself) from accessing these machines.
Generating an ssh Key
The IT staff recommends that you generate an ssh key to move around via ssh within the department network. Using an ssh key is both easier and more secure than retyping your password when you are connecting from one Math Department machine to another. To use an ssh key, do the following.
- Log onto any Linux workstation or research server in the department. You can use ssh as explained above to connect to login0 or login1 for this purpose.
- At the prompt, type "ssh-keygen". Accept the default values. You need not enter a passphrase, so just press enter.
- Add the key you just generated to your authorized_keys file. Type, "cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys"
- To test, type, "ssh magma0". You should be connected to magma0 without having to retype your password.
Note: The login server login1.math.wisc.edu requires the use of ssh keys to connect. You can use this same ssh key for that purpose. Instructions for doing so are different for each ssh client and are therefore beyond the scope of this document. Consult your client's documentation (or google) or ask a member of the IT staff for assistance.