vojtechvitek / sock-proxy

SOCK Proxy for Slack

Slack Desktop app behind a SOCK proxy on macOS

Originally posted at http://www.vojtechvitek.com/posts/slack-desktop-app-behind-a-sock-proxy-on-macos-14045333

Are you behind a company network (or VPN) that restricts access to Slack? Or does the company force you to install a custom root certificate in order for you to log into a certain Slack team using SSO? Here's a solution for you.. First of all, you need a server that is outside of the restricted company network. Create a SOCK proxy to that server using SSH and keep the connection open:

ssh -D 8000 [username]@[server]

1. Go to System Preferences
2. Select your network interface (most probably WIFI or Wired connection)
3. Click on Advanced..
4. Click on Proxies tab
5. Select and check off Automatic Proxy Configuration
6. Paste in this URL: https://raw.githubusercontent.com/VojtechVitek/sock-proxy/master/slack-proxy.pac (you can see the content of the file below)
7. Hit OK and Apply the changes

Applying proxy.pac configuration file hosted on Github on macOS Note: The proxy.pac file must be served from http[s]. Local files don't work on recent macOS systems, since file:// URLs are sandboxed. Use Github :)

function FindProxyForURL(url, host) {
    
    if (shExpMatch(host, "*.slack-msgs.com")) {        
        // Use SOCK proxy,
        // or fall back to a DIRECT traffic.
        // ssh -D 8000 [user]@[server]
        return "SOCKS 127.0.0.1:8000; DIRECT";
    }
    
    return "DIRECT";
}

Here you go. Slack is working again. Enjoy!

sock-proxy's Issues

Slack Desktop App (sshuttle)

We found that, while this socks proxy works for Slack in browser (Safari), It does not work for the Slack Desktop App. A potential workaround you can use, if you have a host you can SSH to that has access to "slack" and all other (internal?) resources you are trying to use is sshuttle (brew install sshuttle). It is only for Mac/Linux (not Windows), but it can be used to effectively "vpn" all your traffic to the target host. An added bonus is that it even works for the Slack Desktop app.

sshuttle --dns -r [user@]SSHSERVER 0/0
NOTE: This requires "sudo" access on client (laptop) side to do the port forwarding.

Then, any traffic that would go out of your computer is forwarded to the SSH host and originates from there instead. There are many other options, but with something like "Slack" where you have a rather dynamic list of hosts and IPs, we decided it would be easiest to just forward all traffic. YMMV.

It might be worth adding this (maybe with some polish) to the README?

https://www.unixmen.com/sshuttle-poor-mans-vpn-ssh/

~tommy