Firefox启动后报错无法访问问题咨询（RHEL 7.4 EC2环境）

Hey there, let’s walk through troubleshooting your Firefox issue on your RHEL 7.4 EC2 instance step by step. It’s weird that it went from just throwing command-line errors to being completely unable to load websites—let’s break this down.

• Reset your Firefox profile: Corrupted profile files are a common culprit for sudden browser failures. Run firefox -P to open the Profile Manager, create a brand new profile, and launch Firefox with it. If the new profile works fine, your old profile is damaged—you can back it up (usually in ~/.mozilla/firefox/) and switch to the new one.
• Check detailed error logs: Launch Firefox from the terminal with firefox --console to see full error output. Look for network-related errors (like failed connections, DNS issues, or proxy problems) that might point to why pages won’t load.
• Test network access outside Firefox: Use a command-line tool like curl https://google.com or wget https://google.com to see if your system can reach external websites at all. If these tools fail too, the problem is with your system’s network, not Firefox itself.

• Verify firewall rules: RHEL 7 uses firewalld by default. Run sudo firewall-cmd --list-all to check if HTTP/HTTPS outbound traffic is allowed. If you don’t see http or https in the services list, add them with:

  sudo firewall-cmd --add-service=http --permanent
  sudo firewall-cmd --add-service=https --permanent
  sudo firewall-cmd --reload
  

• Check proxy settings: Your bot script might have modified system or browser proxy settings.
  • In Firefox, go to Settings → General → Network Settings and make sure it’s set to "No proxy".
  • Check system-wide proxy variables with echo $HTTP_PROXY and echo $HTTPS_PROXY. If these return unexpected addresses, clear them with unset HTTP_PROXY HTTPS_PROXY and restart Firefox.
• Test DNS resolution: Run nslookup google.com to see if your system can resolve domain names. If it fails, edit /etc/resolv.conf to add a public DNS server like nameserver 8.8.8.8, then try accessing websites again.

• Review the script’s code: Check if your new quickstart.py modifies network settings—like setting proxies, altering iptables rules, or using system commands to change firewall configurations. Even unintended changes could block Firefox’s network access.
• Check resource usage: Run top or htop to see if your bot (or any other process) is hogging CPU, memory, or network bandwidth. A resource-heavy process could starve Firefox of network access.
• Test with the bot stopped: Kill the bot process with pkill -f quickstart.py, then restart Firefox. If Firefox starts working again, your script is likely the cause—you’ll need to debug its network-related operations to find the conflict.

Start with the simplest checks (profile reset, curl test) first—they’ll help you quickly narrow down whether the issue is in Firefox, your system network, or the bot script.

内容的提问来源于stack exchange，提问作者Linux Oracle User