Hi,
First of all, we need to understand this Log message then you would be able to understand the actual meaning of these values :
302020
%ASA-6-302020: Built {in | out}bound ICMP connection for faddr { faddr | icmp_seq_num } [( idfw_user)] gaddr { gaddr | icmp_type } laddr laddr [( idfw_user)]
Explanation An ICMP session was established in the fast-path when stateful ICMP was enabled using the inspect icmp command.
Recommended Action None required.
Now, this icmp_seq_num is the number which is used to track which icmp reply is associated to which icmp request. This work with the combination of identifier. It is a part of all the ICMP header data portion(header data part is the combination of identifier and sequence number).
Therefore this 15343 is the icmp_seq_num. Second field is the icmp message type. As the ASA could inspect ICMP packets as well and create a session for the same, ASA keeps track of the ICMP request and reply with this message.
This ICMP sequence number could even seen through linux machines as well if try to ping :
$ ping -c 5 www.example.com
PING www.example.com (93.184.216.119): 56 data bytes
64 bytes from 93.184.216.119: icmp_seq=0 ttl=56 time=11.632 ms
64 bytes from 93.184.216.119: icmp_seq=1 ttl=56 time=11.726 ms
64 bytes from 93.184.216.119: icmp_seq=2 ttl=56 time=10.683 ms
64 bytes from 93.184.216.119: icmp_seq=3 ttl=56 time=9.674 ms
64 bytes from 93.184.216.119: icmp_seq=4 ttl=56 time=11.127 ms
Hope it answers your query.
Regards,
Akshay Rastogi
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