149 lines
5 KiB
Markdown
149 lines
5 KiB
Markdown
# more complex ssh setups
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What do you need to know in order to create more complex ssh setups (for
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instance if you have *two* gitolite servers you are administering)? Once more
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unto the breach, here's more ssh magic!
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In this document:
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* files on client
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* files on the server
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* sanity checks
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* two gitolite servers to manage?
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----
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> But before we get to all that, let's clarify that all this is applicable
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> **only** to the gitolite **admin**. He's the only one who needs both a
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> shell and gitolite access, so he has **two** pubkeys in play.
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> Normal users have only one pubkey, since they are only allowed to access
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> gitolite itself. They do not need to worry about any of this
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> `~/.ssh/config` stuff, and their repo urls are very simple, like:
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> `git@my.git.server:reponame.git`.
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----
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### files on client
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* default keypair; used to get shell access to servers. You would have
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copied this pubkey to the gitolite server in order to log in without a
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password. (On Linux systems you may have used `ssh-copy-id` to do that).
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You would have done this *before* you ran the easy install script, because
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otherwise easy install won't run!
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~/.ssh/id_rsa
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~/.ssh/id_rsa.pub
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* gitolite keypair; the "sitaram" in this is the 3rd argument to the
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`src/00-easy-install.sh` command you ran; the easy install script does the
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rest
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~/.ssh/sitaram
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~/.ssh/sitaram.pub
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### files on the server
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* the authkeys file; this contains one line containing the pubkey of each
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user who is permitted to login without a password.
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Pubkey lines that give shell access look like this:
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ssh-rsa AAAAB3NzaC[snip]uPjrUiAUew== /home/sitaram/.ssh/id_rsa
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On a typical server there will be only one or two of these lines.
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Note that the last bit (`/home/sitaram/.ssh/id_rsa`) is purely a *comment*
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field and can be anything. Also, the actual lines are much longer, about
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400 characters; I snipped 'em in the middle, as you can see.
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In contrast, pubkey lines that give access to git repos hosted by gitolite
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looks like this:
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command="[some path]src/gl-auth-command sitaram",[some restrictions] ssh-rsa AAAAB3NzaC[snip]s18OnB42oQ== sitaram@sita-lt
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You will have many more of these lines -- one for every pubkey file in
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`keydir/` of your gitolite-admin repo, with the corresponding username in
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place of "sitaram" in the example above.
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The "command=" at the beginning ensures that when someone with the
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corresponding private key logs in, they don't get a shell. Instead, the
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`gl-auth-command` program is run, and (in this example) is given the
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argument `sitaram`. This is how gitolite is invoked, (and is told the
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user logging in is "sitaram").
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* config file; this file has an entry for gitolite access:
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~/.ssh/config
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Let's step back a bit. Normally, you might expect to access gitolite
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repos like this:
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ssh://git@server/reponame.git
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But this won't work, because this ends up using the *default* keypair
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(normally), which gives you a command line. Which means it won't invoke
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the `gl-auth-command` program at all, and so none of gitolite's access
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control will work.
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You need to force ssh to use the *other* keypair when performing a git
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operation. With just ssh, that would be
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ssh -i ~/.ssh/sitaram git@server
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but git does not support putting an alternate keypair in the URL.
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Luckily, ssh has a very convenient way of capturing all the mundane
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information (username, hostname, port number (if it's not the default 22),
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and keypair to be used) in one "paragraph". This is what the para looks
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like for us (the easy install script puts it there the first time):
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host gitolite
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user git
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hostname server
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identityfile ~/.ssh/sitaram
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(The "gitolite" can be anything you want of course; it's like an alias for
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all the stuff below it). This ensures that typing
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ssh gitolite
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is equivalent to
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ssh -i ~/.ssh/sitaram git@server
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and therefore this:
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git clone gitolite:reponame.git
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now works as expected, invoking the special keypair instead of the default
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one.
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### sanity checks
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* `ssh gitolite` should get you the `SSH_ORIGINAL_COMMAND` error. If you
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get a command line, something is wrong
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* conversely, `ssh git@server` should get you a command line
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* the "origin" URL in any clones should look like `gitolite:reponame.git`
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instead of something more complex
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### two gitolite servers to manage?
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* they can have the same key; no harm there (example, sitaram.pub)
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* instead of just one ssh/config para, you now have two (assuming that the
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remote user on both machines is called "git"):
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host gitolite
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user git
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hostname server
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identityfile ~/.ssh/sitaram
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host gitolite2
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user git
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hostname server2
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identityfile ~/.ssh/sitaram
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