100 lines
3.3 KiB
Markdown
100 lines
3.3 KiB
Markdown
# SSH Tricks
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Here are some useful SSH tricks for accessing your VM.
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The commands below assume that the SSH public key on your personal machine
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has already been copied to two places:
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1. the `~/.ssh/authorized_keys` file in your CSC home directory
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2. the `~/.ssh/authorized_keys` file of the default user in your VM
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!!! Note
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If you are having trouble with any of the commands below, please don't
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hesitate to ask the [Systems Committee](mailto:syscom@csclub.uwaterloo.ca)
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for assistance.
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Most of the "tricks" below require ProxyJump to have been setup, so we suggest
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reading that first.
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## ProxyJump
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To avoid having to manually SSH to a CSC machine before SSH'ing to your
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VM, you can use the ProxyJump directive. For example, let's say your VM's
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IP address is `172.19.134.121`, and you want to use `corn-syrup` as a jump
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host.
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Add a snippet similar to the following in your `~/.ssh/config` (on your
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personal machine):
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```sh
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Host corn-syrup
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HostName corn-syrup.csclub.uwaterloo.ca
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# Replace this with your username
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User ctdalek
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Host ctdalek-vm1
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# Replace this with the IP address of your VM
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HostName 172.19.134.121
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ProxyJump corn-syrup
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# Replace this with the default user in your VM
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User debian
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```
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Now you can connect to your VM by running
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```sh
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ssh ctdalek-vm1
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```
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!!! Note
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If the name of your SSH key is not one of the default names (e.g. id_rsa,
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id_ed25519), you may also need to specify the `IdentityFile` option.
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## Port forwarding
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Let's say you have a process bound to `localhost:8000` in your VM, and you'd like
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to access it from your personal machine. Then you just need to run the following:
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```sh
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ssh -L 8000:localhost:8000 ctdalek-vm1
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```
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This will forward requests to `localhost:8000` on your personal machine to
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`localhost:8000` on your VM.
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If you want to fork the process to the background, here's one way to do it:
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```sh
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ssh -L 8000:localhost:8000 -CNfq ctdalek-vm1
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```
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Explanation:
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* `-C`: compress (saves bandwidth)
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* `-N`: don't execute a command on the server
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* `-f`: fork the SSH process to the background
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* `-q`: quiet (silences output)
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## Reverse port forwarding
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Let's say you have a process bound to `localhost:8000` on your personal machine,
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and you'd like to access it from your VM. Instead of using `-L`, you want to use
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`-R` instead:
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```sh
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ssh -R 8000:localhost:8000 -CNfq ctdalek-vm1
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```
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This will forward requests to `localhost:8000` in the VM to `localhost:8000` on
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your personal machine.
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## SOCKS proxy
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You probably won't need this one, but it's good to know. This basically allows
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you to use a CSC machine as a proxy for *all* of your Internet traffic for a
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particular application. It's useful when you need to access a website which
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is only available from the campus network.
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First, let's run a SOCKS proxy on e.g. `localhost:8132`:
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```sh
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ssh -D 8132 -CNfq corn-syrup
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```
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You now need to configure your application to use the proxy. For example, in
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Firefox, you can do the following:
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* Visit `about:preferences` in the URL bar
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* Scroll to the bottom, and click the Settings button under 'Network Settings'
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* Select 'Manual proxy configuration'
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* Enter 'localhost' as the SOCKS Host, and 8132 for the port. Also make sure
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'SOCKS v5' is selected.
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After pressing 'OK', you should now be able to visit websites using a campus
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IP address.
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