Proxy PAC file template for selective SSH SOCKS proxies, plus a [re]installation script.

proxy.pac

// Proxy PAC File
// - Used to redirect certain addresses to the server through the SOCKS ssh port (1280 for this file), i.e. 
//   tunnel traffic through server.
// - Useful for easily accessing webpages from services running on a server (Jupyter notebooks, TensorBoard, Spark UI, etc.)
//   that is otherwise locked down by a firewall.
// - To install on OS X/MacOS, go to "Settings->Network->Advanced->Proxies->Automatic Proxy Configuration"
//   and paste the local file url (`file:///absolute/path/to/proxy.pac`).
// - Alternatively, use `./reinstall_proxy.sh`.
// - SSH to the server with `ssh -D 1280 ....`.
function FindProxyForURL(url, host) {
  // Setup a SOCKS proxy on port 1280.
  proxy = "SOCKS5 127.0.0.1:1280; SOCKS 127.0.0.1:1280"

  // Log to `chrome://net-internals/#events` for debugging.
  alert("url: " + url + ", host: " + host)

  // Setup proxy filters.
  // - Use `host` for IP addresses and domain names.
  // - Use `url` for more control over the entire URL (i.e. sub paths).
  // - Protip: Use the above debugging log to determine the `url` and `host` for
  //   a given page.
  // - Protip 2: If you add an entry for your server to `/etc/hosts` in the form of
  //   `IP_address domain_name_url alias`, the `host` can be matched to the `alias`.
  if (shExpMatch(host, "111.111.111.*") ||  // match IP address
      shExpMatch(host, "server*")) {  // match `server1`, `server23`, etc.
    // Log to `chrome://net-internals/#events` for debugging.
    alert(host + " passed!")
    // Route through server.
    return proxy;
  }

  // Route everything else directly!
  return "DIRECT";
}

reinstall_proxy.sh

#!/usr/bin/env bash
set -x  # echo on
DIR="$(cd "$(dirname "$0")" && pwd)"
PROXY_FILE_PATH="$DIR/proxy.pac"
sudo networksetup -setautoproxystate Wi-Fi off
sudo networksetup -setautoproxyurl Wi-Fi file://$PROXY_FILE_PATH
sudo networksetup -getautoproxyurl Wi-Fi

Note: IntelliJ can't run remote debugging using a system SOCKS proxy. Therefore, for this use case, simply open a direct ssh connection with local port forwarding to the correct remote port, then start the remote debug session pointing at that local port.

For a remote debug session pointing at localhost:5007, assuming a debug port is open on REMOTE_HOST:5007:

ssh -L 5007:localhost:5007 -N REMOTE_HOST

Nice job.

I believe the sudo command is unnecessary on a Mac. I can run networksetup -setautoproxystate Wi-Fi off as a non-root user.