How to prevent ICMP Redirect?

Configure the host system to ignore IPv4 ICMP redirect messages.

Table of Contents

Open the /etc/sysctl. conf file.
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 .
Save the changes and close the file.
Run # sysctl -p to apply the configuration.

What is an 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.

Why Disable ICMP Redirects?

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.

How do I enable ICMP on Juniper?

Solution

Log into the web console of the Juniper.
Navigate to Security > Zones/Screen > Select the ‘Untrust’ Zone > Edit > Host inbound traffic – Interface > Under Interface services add in ‘ping’ > OK. Note: To allow pinging of the inside interface select the trusted zone.
Then to save the change click Action > Commit.

What is the relationship between IP and ICMP protocols?

ICMP creates and sends messages to the source IP address indicating that a gateway to the internet, such as a router, service or host, cannot be reached for packet delivery. Any IP network device has the capability to send, receive or process ICMP messages.

How does ICMP help IP in flow control?

Internet Control Message Protocol (ICMP) is used to send control messages to network devices and hosts. Routers and other network devices monitor the operation of the network. When an error occurs, these devices can send a message using ICMP.

What does no ip route cache mean?

The route cache allows outgoing packets to be load-balanced on a per-destination basis. The ip route-cache command with no additional keywords enables fast switching. Our routers generally offer better packet transfer performance when fast switching is enabled, with one exception.

How do I send ICMP traffic?

To send an ICMP echo request packet to the IP address that you specify: Issue the ping command in Privileged Exec mode….The following characters can appear in the display after issuing the ping command:

!
.
?
A—Address mask request message.
a—Address mask reply message.
D—Router discovery advertisement message.

Is ICMP the same as ping?

ICMP is a protocol for sending various messages to report network conditions—it is not ping. The echo request is one of many messages. Ping can be filtered out, but the majority of ICMP message types are required for proper operation of IP, TCP and other protocols.