MacOS – SSH works locally but not remotely

macbook promacosssh

I have remote login turned on, and when I'm at home, I can access the Mac via SSH just fine, by using the local IP address. However when I try to access it when I'm not at home, using the global IP address, it always times out.

Any ideas? Or am I missing something really obvious here?

Best Answer

If all your machines are running Lion or Mountain Lion, and you're using the same iCloud account on them, then you can use iCloud to ssh as described in this blog post from One Thing Well

First, find your Back To My Mac account number by running.

dns-sd -E

Then SSH to another machine like so

ssh -2 -6 username@computer-name.[account number].members.btmm.icloud.com

You can also add this to your ~/.ssh/config to make it easier

Host mac-remote
User username
HostName computername.[account number].members.btmm.icloud.com
AddressFamily inet6
Protocol 2

Mount

SSH lets you create a ~/.ssh/rc that will be executed right after the environment has been set up, but before any shell will be active (so beware of that; search for "sshrc" in man ssh(8) for more informations).

So, to mount your FileVault partition you can add this line to your ~/.ssh/rc file:

hdiutil attach /Users/$USER/$USER.sparsebundle -mountpoint /Users/$USER

Don't worry, your ~/.ssh/rc will be available to the system even before mounting the FileVault partition.

Unmount

Now you have to ensure the unmount at logout, and only if you are connected via ssh. To do that you can use your shell's logout script. These are the logout script paths for the 3 most used shells on Macs (feel free to add more in the comments):

bash: ~/.bash_logout
zsh: ~/.zlogout
(t)csh: ~/.logout

Open (or create) the appropriate file and add:

if [[ -n $SSH_CONNECTION ]]
    then hdiutil detach /Users/$USER/$USER.sparsebundle
fi

IPad – SSH connection to Mac works from the outside but not locally

The router does the NAT on the external interface. However when you ssh to your WAN address the router will recognize packets coming in on on the internal interface as being sent to its own address and will just send them to its local port 22. What you want does exist but isn't often supported, it's called "NAT loopback".

See NAT Loopback Routers

Best Answer

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MacOS – Mount home sparsebundle when SSH

Mount

Unmount

IPad – SSH connection to Mac works from the outside but not locally

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