Reverse SSH is a clever workaround for accessing a device behind an ISP that blocks inbound connections or doesn't allow port forwarding. Here's how it works:

The Core Problem Normally, to access a device at home remotely, you would set up port forwarding on your router so external traffic can reach your server. But many ISPs either block common ports, use CGNAT (Carrier-Grade NAT), or simply don't support port forwarding at all.

How Reverse SSH Solves This Instead of waiting for incoming connections, the local machine initiates an outbound connection to a publicly accessible server (often called a "jump host" or "relay server"). Since outbound connections are almost never blocked, this works around ISP restrictions.

The Setup

Your home machine connects to a public server you control (like a VPS) via SSH. During this connection, you create a remote port forward that tells the public server to listen on a specific port.
Any traffic sent to that port on the public server gets tunneled back through the SSH connection to your home machine.
The Command On your home machine, you would run something like:

ssh -R 8080:localhost:22 user@public-server.com

This tells the public server: "Listen on port 8080, and forward anything received there back through this SSH connection to localhost:22 on my machine."

Accessing Your Home Machine Once the tunnel is established, you can connect from anywhere by SSHing to the public server, which then routes you to your home machine:

ssh -p 8080 user@public-server.com

Why This Works Against ISP Restrictions Traditional Port Forwarding requires inbound connections, is blocked by CGNAT/ISP firewalls, needs router configuration, and exposes your home IP. Reverse SSH uses outbound connections only, works through NAT/firewalls, requires no router changes, and hides your home IP behind the relay.

Important Considerations Security: The public server becomes a single point of failure and potential attack surface. Use strong authentication (SSH keys, not passwords) and consider additional encryption layers.

Reliability: If your home machine loses power or internet, the tunnel breaks. Some people use auto-reconnect scripts or tools like autossh to maintain persistence.

Latency: Traffic routes through the public server, adding a hop. Performance depends on that server's bandwidth and location.

Cost: You need a publicly accessible server (VPS costs money, though free tiers exist).

Legal/Ethical: This is a legitimate networking technique, but ensure you are not violating any terms of service or attempting to bypass restrictions you shouldn't.

Is there a specific aspect of this setup you would like me to elaborate on? I could walk through the configuration in more detail, discuss security hardening, or explore alternatives like Tailscale or Cloudflare Tunnel if you are interested.

Cheers!
-warmfuzzy

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