Because ICMP traffic, notably ICMP ECHO REQUEST-0 and ECHO REPLY-8 are used in network diagnostic sequences.
To ping is to issue an ICMP Type 8 (ICMP Echo Request) to a host which according to RFC1122 it must reply to. (In reality this may be seen as a security risk.). The format of a successful response has type and code of 0. If you're operating down at this level you'll need to examine ICMP in more detail. If you have a sockets interface then you may just get a reply event. Sometimes people call these "pongs". ie Ping? Pong. Ping? Pong.
Block them at the router. Understand, however, that ICMP Echo Request/Reply (Ping) is a standard network troubleshooting tool, and that disabling it can compromise the ability to troubleshoot certain problems.
Cisco IOS firewalls handle ICMP (Internet Control Message Protocol) traffic by inspecting and filtering it based on configured access control lists (ACLs) and security policies. By default, ICMP messages such as echo requests (ping) can be allowed or denied depending on the rules set in the firewall configuration. Administrators can customize the handling of specific ICMP types, enabling or disabling traffic as needed for network security and performance. Additionally, the firewall can log ICMP traffic for monitoring and troubleshooting purposes.
To enable ICMP (Internet Control Message Protocol) on a Cisco device, you typically need to ensure that the device's access control lists (ACLs) allow ICMP traffic. If you have an ACL that is blocking ICMP, you can modify it to permit ICMP packets by adding a rule like permit icmp any any. Additionally, make sure that any firewall features or security settings on the device do not block ICMP traffic. Once configured, you can test ICMP connectivity using tools like ping.
There really is no "port" for icmp but there is a icmp code. If you are looking for the icmp code for echo-reply it is 0 and the echo is 8 For an access list you could do the following: permit icmp any any echo-reply permit icmp any any echo Or the same using the icmp code permit icmp any any 0 permit icmp any any 8
There really is no "port" for icmp but there is a icmp code. If you are looking for the icmp code for echo-reply it is 0 and the echo is 8 For an access list you could do the following: permit icmp any any echo-reply permit icmp any any echo Or the same using the icmp code permit icmp any any 0 permit icmp any any 8
Standard ACLs filter IP packets at the source address only. Extended ACLs filter IP packets based on other protocols including; source and destination IP addresses, source and destination TCP and UDP ports and protocol types (IP, ICMP, UDP, TCP & Protocol No). The protocol that is implicitly denied due to filtration is HTTP.
Pretty much every protocol used for malicious traffic and Trojans is also used for legitimate traffic. You cannot block all bad traffic just by filtering on protocols. When given that ICMP and HTTP are both allowed, if you have to block one, block ICMP. Choices were: DNS DHCP ICMP HTTP https://library.skillport.com/courseware/cbtlib/TPSY0201/metadata/eng/TPSY0201B.htm?
ICMP does not have a port like TCP and UDP.
Because ICMP is on the network layer
All ICMP Error Messages
icmp request is orginated on the OSI network layer with ip protocol.
ICMP is the internet control access protocol . ICMP is the plrotocol that should be allowed when not able to ping a remote device residing behind a firewall. ICMP is the protocol of network layer.
If devices on a network are properly configured, a host sending ICMP to a default gateway must receive a reply. ICMP simply means ping.