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.
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.
Assuming IPv4 ICMP. Ping uses IP for transport. Ping in itself is an "Echo Request", which is a function of the ICMP protocol. The IP Packet will carry the ICMP protocol from end-to-end. ICMP has a protocol number of 1, so the "Protocol" field in the IPv4 header will contain "1" as a reference to the ICMP payload. For IPv6, ICMPv6 is used, and the transport will be IPv6.
no