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I wasn't able to ping to my ec2 server although I've done the following command:

ec2-authorize default -P icmp -t -1:-1 -s

when I try this again it gives me:

Client.InvalidPermission.Duplicate: The permission '' has already been authorized on the specified group

now when I ping from my laptop it gives me:

PING ( 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3

any idea on what to try on next?

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since you pasted a public IP, i had to see...

64 bytes from icmp_req=1 ttl=51 time=192 ms
64 bytes from icmp_req=2 ttl=51 time=191 ms

looks like you may be limiting icmp at your location?

otherwise, if this was fixed after posting, remember that allowing icmp open to the world means that you will be hit by the many evilcrawlers that find a box with icmp, and then mount several hundred/thousand canned attacks it. easier just to be invisible, and allow icmp from a few ips (/32's). the same goes for everything else not needed publicly. opening tcp/22 to the world, and having sshd listen on default, will generate a few hundred thousand entries in your secure or auth log.

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