On Wed, Feb 15, 2012 at 04:51:44PM -0600, Anton Kapela wrote:
On Wed, Feb 15, 2012 at 4:36 PM, Chuck Anderson <cra@wpi.edu> wrote:
ICMP is bad, and should be completely blocked for "security".
I can't tell if this reply is to say "this ought to be done" or if "this is often done, and should not be."
Clarify?
This thread is about misconceptions. What I said was a common misconception that "all ICMP should be blocked for security reasons". In reality, some kinds of ICMP are REQUIRED for proper functioning of an internetwork for things like Path MTU Discovery (ICMP Fragmentation Needed/Packet Too Big). Other kinds of ICMP are good to allow for being nice to the users and applications by informing them of an error immediately rather than forcing them to wait for a timeout (ICMP Destination Unreachable).