Ubuntu

unable to ping but can browse the internet using firefox

Asked by Harish

Unable to ping internet from terminal or network tools, however can still browse internet using firefox. Pinging web-site such as google.com shows ip address for the web-site, but says 100% package loss. Ping works normal when pinged to local intranet address. Same problem is also happening with other utilities such as traceroute. I have checked the dns and other network settings for my organization, they are normal. The problem started after my organization removed proxy server and allowed us direct connection to internet. I have checked my proxy settings and they point to no proxy option.

This question was asked as a part of question #23296, however it appears question #23296 dealt with multiple issue related to network problem and one of them answered. The problem listed is unanswered hence any information will be highly appreciated.

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Solved by:
Alexander Zolotko
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Best Alexander Zolotko (azolotko) said : 		#1

Ping works by sending ICMP “echo request” packets to the target host and listening for ICMP “echo response” replies. If your gateway (server or network device you're using to route Internet traffic from/to your intranet) drops ICMP packets, tools like ping and traceroute will not work as you expected.

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Harish (harish-narl) said : 		#2

Thank you Alexander. Your answer explains the source of the problem. Is there a way around this? Are there good reasons for blocking ICMP packets for network administrator?

Thanks again!

Harish

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Harish (harish-narl) said : 		#3

Thanks Alexander Zolotko, that solved my question.

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Alexander Zolotko (azolotko) said : 		#4

Blocking of ICMP packets can save the network from some of network attacks.