It has two third party repos, EPEL and the REMI repo. I don’t see any untoward traffic over the few minutes I left it running. I didn’t get any choice on security policy for the install as it was a pre canned Digitalocean image for Rocky Linux that they provide. Inspecting the packetdump file with wireshark, my own pings are the only ping traffic I see but I didn’t run it long as the server is busy running two web sites and the file was growing quite fast. That captured everything going in and out of eth0. I just tested it myself on a digitalocean cloud based VM, I generated some ping traffic to the VM and tcpdump recorded it along with all the other stuff that was happening at the time. It does capture ICMP, ESP, UDP and well as TCP and other protocols as well. So if we want to check any IP or website is reachable or not, we can use ping or traceroute which internally use ICMP protocol.Just a comment about tcpdump. That means we did not receive any ICMP reply for any ICMP request. Let’s ping some ip address which is not accessible. What happens if IP address is not reqachable: Let’s look into the Identification field inside IPv4. Now let’s see ICMP request and ICMP reply side by side in a picture. Now for the same packet select ICMP part in Wireshark. Also IP layer mentioned the protocol as ICMP. Now select ICMP request packet in Wireshark and look into IPv4 layer.Īs this is ICMP request packet so we can see source IP as my system IP address and destination IP as Google’s one IP address. Number of ICMP reply: From capture we can see there are 4 ICMP reply packets. Number of ICMP request: From capture we can see there are 4 ICMP request packets. Note: We have to put filter ‘icmp’ as we are interested only in ICMP packets. Here is the ICMP request and reply packets for Google ping. Let’s check what happens in Wireshark when we ping to Google or 192.168.1.1. Step5: Stop Wireshark and put “ICMP” as filter in Wireshark. Instead we can do ping to ip address also. That means ICMP request packets = ICMP reply packets.

Here is the snapshot for successful ping to Google. Ping Make sure you have internet connection or ping will be failedJ.

Wireshark display filter icmp code 123