How to block ICMP and IGMP?

Routers
1

How to block ICMP and IGMP? I just don’t need them. What will I lose if they will be blocked?

I read somewhere that I should block as much as possible to prevent as much breaches as possibly

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Please set up these firewall rules what your requirements in the Luci.

3

Blocking inbound ICMP and IGMP in a NATed LAN can lead to:

  1. Path MTU Discovery Issues: ICMP is essential for Path MTU Discovery. Blocking ICMP can prevent "Fragmentation Needed" messages, causing packet loss or inefficient communication.
  2. Troubleshooting Difficulties: ICMP is crucial for diagnostics (e.g., ping, traceroute).
  3. Multicast Communication Problems: IGMP manages multicast groups, and blocking it disrupts related applications.
  4. Network Performance Degradation: Without IGMP, multicast traffic may flood the network.
  5. Application Connectivity Issues: Some apps (e.g., gaming, VoIP) rely on ICMP and IGMP.
  6. Reduced Security Insights: ICMP aids in network health and security monitoring.

If you're sure IGMP isn't needed, you may want to block it and consider blocking only ICMP echo requests (ping) instead of all ICMP traffic on OpenWrt.

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