Should I disable ICMP redirect?

If an attacker is able to forge ICMP redirect packets, he or she can alter the routing tables on the host and possibly subvert the security of the host by causing traffic to flow via a path you didn’t intend. It’s strongly recommended to disable ICMP Redirect Acceptance to protect your server from this hole.

What is ICMP redirect in Linux?

An ICMP redirect packet is generated by a router to inform a host of a better route to some specific destination. The recipient of an ICMP redirect overrides its route table with the information given in the redirect packet.

What are ICMP redirect?

An ICMP redirect message is an out-of-band message that is designed to inform a host of a more optimal route through a network, but possibly used maliciously for attacks that redirect traffic to a specific system.

How do I disable IP source routing in Linux?

To Disable or Enable IP Forwarding

  1. To disable IP forwarding, set the parameter in the /etc/sysctl.conf file as follows: net.ipv4.ip_forward = 0.
  2. To enable IP Forwarding, set the parameter in the /etc/sysctl. conf file as follows. net.ipv4.ip_forward = 1.

How do I disable ICMP redirects in Linux?

Configure the host system to ignore IPv4 ICMP redirect messages.

  1. Open the /etc/sysctl. conf file.
  2. If the values are not set to 0 , add the following entries to the file or update the existing entries accordingly. Set the value to 0 .
  3. Save the changes and close the file.
  4. Run # sysctl -p to apply the configuration.

How do I stop ICMP from redirecting?

How to Prevent ICMP Redirects

  1. Set the ignore redirects property to 1 for IP packets, then verify the current value. ICMP redirect messages modify the host’s route table and are unauthenticated.
  2. Prevent sending ICMP redirect messages.

How do I disable ICMP redirects?

What is an ICMP packet?

ICMP packets are IP packets with ICMP in the IP data portion. ICMP messages also contain the entire IP header from the original message, so the end system knows which packet failed. The ICMP header appears after the IPv4 or IPv6 packet header and is identified as IP protocol number 1.

How do I disable IP source routing?

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “MSS: (DisableIPSourceRouting) IP source routing protection level (protects against packet spoofing)” to “Highest protection, source routing is completely disabled”.

What is IP source routing?

Source routing is a feature of the IP protocol which allows the sender of a packet to specify which route the packet should take on the way to its destination (and on the way back). Source routing was originally designed to be used when a host did not have proper default routes in its routing table.

Under what conditions will an ICMP redirect message be sent?

Cisco IOS routers will send ICMP redirects when the following conditions are met: The IP packet should be received and transmitted on the same interface. The source IP address of the incoming packet should be on the same subnet as the new next hop IP address. The IP packet doesn’t use source routing.

What is the RFC for ICMP?

RFC 792
RFC 792 – Internet Control Message Protocol.