Burp Suite: Fix Packet Forwarding

TL;DR

Burp Suite isn’t forwarding traffic? This guide covers common causes and fixes, from browser settings to Burp configuration. We’ll get your packets flowing!

Troubleshooting Steps

1. Check Browser Proxy Settings
   • Most issues stem from incorrect browser proxy configurations.
   • Chrome/Edge: Go to Settings > System > Open your computer’s proxy settings. Ensure “Automatically detect settings” is enabled, or manually configure the proxy to 127.0.0.1 and port 8080 (Burp’s default).
   • Firefox: Go to Settings > General > Network Settings > Settings... Select “Manual proxy configuration”. Enter 127.0.0.1 as the HTTP Proxy and port 8080. Also check ‘Use this proxy server for all protocols’.
   • Safari: Go to System Preferences > Network > Advanced... > Proxies. Select “Web Proxy (HTTP)” and enter 127.0.0.1 port 8080.
2. Verify Burp Suite is Running and Listening
   • Ensure Burp Suite Professional or Community Edition is open and running.
   • Check the Burp Suite UI: The Proxy tab should be active, and you should see a status message indicating it’s listening on 127.0.0.1:8080 (or your configured port).
3. Install the Burp Suite CA Certificate in Your Browser
   • Burp intercepts HTTPS traffic using a Man-in-the-Middle (MITM) technique, requiring its certificate to be trusted by your browser.
   • In Burp Suite, go to Proxy > Options > Proxy Listeners. Select the listener you’re using and click ‘Import/Export CA Certificate’. Save the certificate (usually as a .der file).
   • Chrome/Edge: Go to Settings > Privacy and security > Security > Manage certificates. Import the saved certificate under “Trusted root certification authorities”.
   • Firefox: Press Alt + Shift + I to open settings, then go to Privacy & Security > Certificates > View Certificates > Authorities. Import the certificate.
   • Safari: Double-click the .der file in Finder and follow the prompts to add it to your Keychain Access. Trust the certificate by double clicking on it again within Keychain Access, then changing its trust settings.
4. Check Burp Suite’s Interception Mode
   • Burp has different interception modes: Intercepting, Passive, and Off. If in ‘Off’ mode, it won’t intercept or forward traffic.
   • Go to Proxy > Options and ensure the Interception Mode is set to Intercepting if you want to actively inspect requests. For simply forwarding without inspection, use Passive.
5. Firewall/Antivirus Interference
   • Sometimes, firewalls or antivirus software can block Burp Suite’s traffic.
   • Temporarily disable your firewall and antivirus to see if that resolves the issue. If it does, configure them to allow Burp Suite’s connections (port 8080 by default).
6. Check for Other Proxies
   • Ensure no other proxy settings are active in your system or browser. Conflicting proxies can cause issues.
   • Clear any environment variables that might be setting a proxy (e.g., http_proxy, https_proxy). On Linux/macOS:

     unset http_proxy https_proxy all_proxy no_proxy

7. Burp Suite Updates
   • Outdated Burp Suite versions can sometimes have bugs. Ensure you’re using the latest version.
   • Check for updates within Burp Suite itself: Help > Check for Updates.