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| {{header|infra}} | | {{header|infra}} |
| {{shortcut|ISOP:SSHACCESS}} | | {{shortcut|ISOP:SSHACCESS}} |
| | This SOP has moved to the fedora Infrastructure SOP git repo. Please see the current document at: https://infrastructure.fedoraproject.org/infra/docs/docs/sysadmin-guide/sops/sshaccess.rst |
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| == Contact Information ==
| | For changes, questions or comments, please contact anyone in the Fedora Infrastructure team. |
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| Owner: sysadmin-main
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| Contact: #fedora-admin or admin@fedoraproject.org
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| Location: PHX2
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| Servers: All PHX2 and VPN Fedora machines
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| Purpose: Access via ssh to Fedora project machines.
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| === Introduction ===
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| This page will contain some useful instructions about how you can safely
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| login into Fedora PHX2 machines successfully using a public key
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| authentication. As of 2011-05-27, all machines require a SSH key to
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| access. Password authentication will no longer work. Note that this SOP
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| has nothing to do with actually gaining access to specific machines. For
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| that you MUST be in the correct group for shell access to that machine.
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| This SOP simply describes the process once you do have valid and
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| appropriate shell access to a machine.
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| === SSH configuration ===
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| '''First of all: (on your local machine)'''
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| <pre>
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| nano ~/.ssh/config
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| </pre>
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| '''then,''' add the following:
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| <pre>
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| Host *.phx2.fedoraproject.org *.fedoraproject.org fedorahosted.org *.fedorahosted.org fedorapeople.org
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| User FAS_USERNAME
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| # Add other machines to this line as desired.
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| Host *.phx2.fedoraproject.org 10.5.125.* 10.5.126.* 10.5.127.* *.vpn.fedoraproject.org
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| ProxyCommand ssh -W %h:%p bastion.fedoraproject.org
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| </pre>
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| One slight annoyance with this method is that you must include the
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| .phx2.fedoraproject.org part when you SSH to Fedora machines in order
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| for the connection to be tunneled through bastion. If this is an issue,
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| here are two possible ways to avoid it:
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| 1. You can add aliases for each of the Fedora machines you login to by
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| modifying the Host line:
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| <pre>
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| Host *.phx2.fedoraproject.org 10.5.125.* 10.5.126.* 10.5.127.* *.vpn.fedoraproject.org puppet01 noc01 # list all hosts here
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| </pre>
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| 2. You can proxy everything through bastion by default and exclude hosts
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| that you connect to directly:
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| <pre>
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| # List all host you SSH to that are NOT Fedora machines
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| # make sure to include bastion here as well!
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| Host allyourlocalmachines bastion.fedoraproject.org
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| ProxyCommand none
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| Host *
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| ProxyCommand ssh -W %h:%p bastion.fedoraproject.org
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| </pre>
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| Keep in mind that if bastion ever goes down and you need to access
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| things, you'll want to comment this section out.
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| === SSH Agent forwarding ===
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| You should normally have:
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| <pre>
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| ForwardAgent no
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| </pre>
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| For Fedora hosts (this is the default in OpenSSH). You can override this
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| on a per-session basis by using '-A' with ssh. SSH agents could be
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| misused if you connect to a compromised host with forwarding on (the
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| attacker can use your agent to authenticate them to anything you have
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| access to as long as you are logged in). Additionally, if you do need
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| SSH agent forwarding (say for copying files between machines), you
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| should remember to logout as soon as you are done to not leave your
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| agent exposed.
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| === Troubleshooting: ===
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| * 'channel 0: open failed: administratively prohibited: open failed': If you receive this message for a machine proxied through bastion, then bastion was unable to connect to the host. This most likely means that tried to SSH to a nonexistent machine. You can debug this by trying to connect to that machine from bastion.
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| * if your local username is different from the one registered in FAS, please remember to set up a '''User''' variable (like above) where you specify your FAS username. If that's missing SSH will try to login by using your local username, thus it will fail.
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| * ssh -vv is very handy for debugging what sections are matching and what are not.
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| * If you get access denied several times in a row, please consult with #fedora-admin. If you try too many times with an invalid config your IP could be added to denyhosts.
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| * If you are running an OpenSSH version less than 5.4, then the -W option is not avaliable. In that case, use the following ProxyCommand line instead:
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| <pre>
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| ProxyCommand ssh -q bastion.fedoraproject.org exec nc %h %p
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| </pre>
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| [[Category:Infrastructure SOPs]] | | [[Category:Infrastructure SOPs]] |
