Port Forwarding Guide

Only needed if a transfer won’t connect. Works on Windows and Linux.

What you’re doing

ShardLock sends files directly, computer to computer. For that, the person receiving a file needs their router to let the sender’s connection reach their PC. “Port forwarding” tells your router: “when a ShardLock connection arrives on port 9500, hand it to my computer.” You set this up once.

Step 1 — Find your computer’s local IP address

This is your PC’s address on your home network (starts with 192.168. or 10.).

Windows

1. Press Win + R, type cmd, press Enter.
2. Type ipconfig and press Enter.
3. Find IPv4 Address under your active adapter — e.g. 192.168.1.42. Write it down.

Linux (Pop!_OS / Ubuntu)

1. Open a Terminal.
2. Run:

   hostname -I

   The first address (e.g. 192.168.1.42) is your local IP. (Or run ip addr show and look for the inet 192.168.… line on your Wi-Fi/Ethernet adapter.)

Step 2 — Find your router’s address (the “gateway”)

Windows

In the same ipconfig output, find Default Gateway — usually 192.168.1.1 or 192.168.0.1.

Linux

ip route | grep default

The address after via is your router (e.g. 192.168.1.1).

Step 3 — Log into your router

1. Open a web browser and go to http:// + your gateway address (e.g. http://192.168.1.1).
2. Sign in. The username/password are often printed on a sticker on the router itself (common defaults: admin / admin or admin / password).

Step 4 — Add the port-forward rule

Every router’s menus differ, but the setting is called Port Forwarding (sometimes under Advanced, NAT, Firewall, Virtual Server, or Gaming). Add a new rule with:

• Name: ShardLock
• Protocol: TCP
• External / Start port: 9500
• Internal / End port: 9500
• Device / Internal IP: your computer’s local IP from Step 1 (e.g. 192.168.1.42)
• Enabled: yes

Save / Apply. That’s the router done.

AT&T Fiber gateways (BGW210 / BGW320 / BGW620)

AT&T’s gateways are a little different, so here are the exact steps:

1. In a browser go to http://192.168.1.254 — note it’s .254, not .1, on AT&T.
2. Go to Firewall → NAT/Gaming. You’ll be asked for the Device Access Code — it’s printed on the sticker on the side of the gateway.
3. Under Custom Services (or “Add a new user-defined application”), create one: Name ShardLock, Protocol TCP, Global port range 9500 to 9500, Base Host port 9500. Save it.
4. Back on NAT/Gaming, pick ShardLock from the application list, choose your computer from the device dropdown, and click Add.

What to say when you call AT&T

“I’m on AT&T Fiber and I need to accept inbound connections for an application. Can you confirm I have a public IPv4 address and that I’m not behind CGNAT / carrier-grade NAT? If I am, please move me to a public (dynamic) IP.”

Most AT&T Fiber lines already have a public IP, so usually the gateway steps above are all you need — the call is only if the CGNAT check above says otherwise.

Step 5 — Allow it through your computer’s firewall

Windows

Open Command Prompt as Administrator (right-click → Run as administrator) and run:

netsh advfirewall firewall add rule name="ShardLock" dir=in action=allow protocol=TCP localport=9500

Or do it in the GUI: Windows Security → Firewall & network protection → Advanced settings → Inbound Rules → New Rule → Port → TCP → 9500 → Allow.

Linux (only if you turned the firewall on)

Pop!_OS ships with its firewall off by default, so usually there’s nothing to do. If you enabled ufw, allow the port both directions (in to receive, out to send):

sudo ufw allow 9500/tcp
sudo ufw allow out 9500/tcp

Step 6 (recommended) — Keep your PC’s IP from changing

Routers hand out local IPs that can change on reboot, which would break your forward. In your router settings, look for DHCP Reservation (or Static Lease) and reserve your computer’s current IP to its device, so it stays the same.

Test it

Make sure ShardLock is open (it needs to be running to receive), then have a buddy on a different network send you a small file. If it connects, you’re done — you only have to set this up once.