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New Member

echo and echo reply

what is the difference between echo and echo reply in icmp permit any echo inside

and vice versa..

5 REPLIES

Re: echo and echo reply

One is a request, the other is the reply.

New Member

Re: echo and echo reply

so does the request send only a request and reply both request and reply?

Re: echo and echo reply

Hi,

ICMP echo-request is generated by the device from which the PING is originated. ICMP echo-reply is sent by the target device to the requesting device stating that it received the echo-request.

HTH

Sundar

New Member

Re: echo and echo reply

my ques here is if yoou have only one either echo request or echo reply what will be the effect as given in command

icmp permit any echo-request inside

or

icmp permit any echo-reply inside

Re: echo and echo reply

a. icmp permit any echo-request inside

- can send ping request to inside interface, but sender will not get reply.

b. icmp permit any echo-reply inside

- can get reply when pinging inside interface

To control ping request directed to your firewall interfaces, allow only specific ICMP type, i.e, allow only trusted IP/host to ping.

Carefully when allow ping to your outside interface from any internet/external host, esp to avoid ping/icmp attack.

http://www.cisco.com/en/US/customer/products/ps6120/products_command_reference_chapter09186a008063f9fd.html#wp1629224

http://www.rhyshaden.com/icmp.htm

http://groups.google.com.my/group/comp.security.firewalls/browse_thread/thread/2e4d1cf5ce99e9cf/27da7044c784e60e?lnk=st&q=why+ICMP+to+allow+request+reply&rnum=3&hl=en#27da7044c784e60e

Cheers!

AK

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