Setting up a router to route all devices through a proxy involves configuring the router's network settings to redirect all outgoing internet traffic from connected clients to a specified proxy server before it reaches its final destination.

Overview of Router-Based Proxying

Routing all network traffic through a proxy at the router level offers centralized control over internet access for every device connected to the network, including those without native proxy configuration options (e.g., smart TVs, IoT devices). This method ensures consistent application of proxy policies, such as IP address masking, geo-restriction bypassing, or content filtering, across the entire local area network (LAN).

How It Works

When a router is configured to use a proxy, it intercepts outgoing network requests from any connected device. Instead of sending these requests directly to the internet, the router forwards them to the designated proxy server. The proxy server then makes the request to the internet on behalf of the router (and thus the client device) and returns the response to the router, which then passes it back to the original client.

Prerequisites

Before attempting a router proxy setup, ensure the following:

• Proxy Server Details:
  • Proxy server IP address or hostname.
  • Proxy port.
  • Authentication credentials (username and password) if required.
  • Proxy type (HTTP, HTTPS, SOCKS4, SOCKS5).
• Router Access: Administrative access to your router's configuration interface (web GUI or SSH).
• Router Capabilities:
  • Custom Firmware: Most consumer routers lack native support for transparent proxying. Custom firmware like OpenWrt, DD-WRT, or pfSense/OPNsense (for dedicated router hardware) is often required. These firmwares provide the necessary flexibility to install proxy software and configure firewall rules.
  • Processor and Memory: Routing all traffic through a proxy, especially with SSL/TLS interception, is resource-intensive. Ensure the router has sufficient CPU and RAM.
  • Storage: Enough flash storage to install proxy packages (e.g., Squid, TinyProxy).

Router Proxy Implementation Methods

The approach to setting up a router proxy depends heavily on the router's firmware and capabilities.

1. Native Proxy Settings (Rare)

Some high-end enterprise routers or specialized security appliances may offer built-in proxy configuration fields. This is uncommon for consumer-grade routers. If available, these settings typically involve specifying the upstream proxy server's IP and port.

2. Transparent Proxy via Custom Firmware (Recommended for "All Devices")

This is the most common and robust method for consumer hardware running custom firmware. It involves installing a local proxy server on the router itself and then using firewall rules to redirect all relevant outgoing traffic to this local proxy, which then forwards it to the external (upstream) proxy.

Example: OpenWrt/DD-WRT with Squid/TinyProxy and iptables

This method involves:
1. Installing a local proxy server: Packages like squid (more feature-rich, higher resource usage) or tinyproxy (lightweight, HTTP/HTTPS only) can be installed on the router.
2. Configuring the local proxy: The local proxy is set up to act as a forwarder, sending all requests to your external proxy server.
3. Configuring firewall rules (iptables): Rules are added to redirect HTTP (port 80) and HTTPS (port 443) traffic from LAN clients to the local proxy's listening port.

Step-by-Step (Conceptual for OpenWrt):

1. SSH into Router:
   bash ssh root@<router_ip>

2. Install Proxy Package (e.g., TinyProxy):
   bash opkg update opkg install tinyproxy
   For Squid, the process is similar but configuration is more complex.

3. Configure TinyProxy:
   Edit /etc/tinyproxy.conf.

   • Set Port to an unused port (e.g., 8888).
   • Set Listen to 0.0.0.0 or the router's LAN IP.
   • Configure Upstream to point to your external proxy server:
     Upstream <proxy_type> <external_proxy_ip_or_hostname>:<external_proxy_port> # Example for HTTP proxy: # Upstream http proxy.example.com:8080 # Example for SOCKS5 proxy: # Upstream socks5 proxy.example.com:1080
   • If authentication is required for the upstream proxy, configure BasicAuth or DigestAuth directives based on TinyProxy's documentation.
   • Allow access from your LAN:
     Allow 192.168.1.0/24 # Adjust to your LAN subnet
   • Restart TinyProxy:
     bash /etc/init.d/tinyproxy restart /etc/init.d/tinyproxy enable # To start on boot

4. Configure iptables Redirection:
   Add rules to /etc/firewall.user (or via uci for persistent rules). These rules redirect outgoing HTTP/HTTPS traffic from LAN to the local TinyProxy instance.

   ```bash

   Redirect HTTP (port 80) to TinyProxy (port 8888)

   iptables -t nat -A PREROUTING -i br-lan -p tcp --dport 80 -j REDIRECT --to-port 8888

   Redirect HTTPS (port 443) to TinyProxy (port 8888)

   iptables -t nat -A PREROUTING -i br-lan -p tcp --dport 443 -j REDIRECT --to-port 8888
   ```
   Note: Redirecting HTTPS traffic transparently requires the proxy to perform SSL/TLS interception, which involves installing a custom CA certificate on every client device to avoid certificate warnings. Without this, only HTTP traffic will be fully transparently proxied, and HTTPS traffic might fail or bypass the proxy if the proxy does not support transparent SSL/TLS interception or if clients reject the proxy's self-signed certificates.

5. Restart Firewall:
   bash /etc/init.d/firewall restart

3. Router-based VPN Client (Alternative to Proxy)

While not strictly a "proxy setup," configuring a VPN client directly on the router achieves a similar goal: routing all network traffic from connected devices through an external server. Many custom firmwares (OpenWrt, DD-WRT) and even some stock firmwares support OpenVPN or WireGuard client configurations. This method encrypts all traffic and changes the apparent IP address for all devices without per-device configuration.

Comparison: Router Proxy vs. Router VPN

Proxy Types and Considerations

• HTTP/HTTPS Proxies: Primarily designed for web traffic. HTTP proxies can cache content, which might improve performance for frequently accessed resources. HTTPS proxies require SSL/TLS interception for full transparency.
• SOCKS Proxies (SOCKS4/SOCKS5): More versatile, capable of proxying any type of TCP connection (and UDP for SOCKS5). SOCKS proxies operate at a lower level than HTTP proxies. If your external proxy is SOCKS, your local proxy (e.g., TinyProxy, Squid) must be configured to forward to a SOCKS upstream, or you need a SOCKS-aware redirector.
• Transparent Proxy: The client device is unaware it's using a proxy; all redirection happens at the router level. This is the goal for "all devices through proxy."
• Explicit Proxy: Requires manual configuration on each client device (specifying proxy IP and port). Not suitable for routing all devices through the router without individual client setup.

Security and Performance Implications

Security

• Trust: The security of your traffic heavily relies on the trustworthiness of the proxy server. An untrusted proxy could log your activities or inject malicious content.
• SSL/TLS Interception: For full transparent proxying of HTTPS traffic, the proxy must perform SSL/TLS interception (Man-in-the-Middle). This requires installing the proxy's root certificate on all client devices to avoid security warnings. Without this, HTTPS traffic may not be fully proxied or will generate certificate errors.

Performance

• Latency: Adding an extra hop (router -> local proxy -> external proxy -> internet) inherently increases latency.
• Bandwidth: The proxy server's bandwidth can become a bottleneck.
• Router Resources: The router's CPU and RAM are utilized for running the local proxy software and processing firewall rules. This can lead to performance degradation if the router is underpowered or handles heavy traffic.

Troubleshooting Common Issues

• No Internet Access:
  • Verify the external proxy server is online and accessible from the router.
  • Check firewall rules: Ensure they are correctly configured and not blocking legitimate traffic or the proxy's operations.
  • Review proxy configuration: Incorrect upstream details or authentication issues.
  • Router resources: Router might be overloaded.
• SSL/TLS Errors (for HTTPS traffic):
  • This is expected if the proxy is performing SSL/TLS interception without the proxy's root certificate installed on the client device.
  • If using a transparent proxy for HTTPS without interception, traffic might fail or be bypassed.
• Specific Applications Not Working:
  • Some applications use non-standard ports or protocols that might not be covered by your iptables redirection rules (e.g., only redirecting 80/443).
  • Applications might have built-in proxy detection or require specific proxy types (e.g., SOCKS for gaming, certain VoIP).
  • DNS resolution issues: Ensure the router's DNS settings are not conflicting or being redirected unexpectedly.