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22249 Views 1 Helpful 5 Replies

echo and echo reply

aksher Level 1 Options

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‎10-09-2006 12:17 PM - edited ‎03-09-2019 04:27 PM

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

and vice versa..

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5 Replies 5 Collin Clark VIP Alumni Options

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‎10-09-2006 12:18 PM

One is a request, the other is the reply.

0 Helpful Reply aksher Level 1 In response to Collin Clark Options

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‎10-09-2006 12:31 PM

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

0 Helpful Reply sundar.palaniappan Level 10 In response to aksher Options

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‎10-09-2006 01:01 PM

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

1 Helpful Reply aksher Level 1 In response to sundar.palaniappan Options

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‎10-09-2006 02:01 PM

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

0 Helpful Reply a.kiprawih Level 7 In response to aksher Options

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‎10-09-2006 04:50 PM

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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