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I can browse all the websites in my company work station, but not open the command prompt and ping any website. This has happened in 2 of my previous companies too. Do companies block ping?Why do companies do that ?

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Could you clarify what you mean, please? Does ping not return anything or can't you execute ping (This program has been blocked or something like this). –  TeX HeX Aug 4 '11 at 6:51
    
"Ping request could not find host google.com. Please check the name and try again" –  vinoth Aug 4 '11 at 7:04
    
do you browse via a company squid proxy ? –  Sirex Aug 4 '11 at 7:29
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Because the sysadmins are either ignorant, or being overly cautious. I sure hope they haven't completely blocked ICMP since that breaks PMTUD. –  Zoredache Aug 4 '11 at 8:05
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It's probably not blocking ping, but rather blocking name resolution requests. Your company is using a proxy, other "direct" internet access is disabled (HTTP / ping / name resolution / ...). –  Konerak Aug 4 '11 at 12:33

2 Answers 2

up vote 6 down vote accepted

It has to do with the issues caused by it in the past ("Ping of death"), so some sites block it at the firewall level to avoid them:

On the Internet, ping of death is a denial of service (DoS) attack caused by an attacker deliberately sending an IP packet larger than the 65,536 bytes allowed by the IP protocol.

One of the features of TCP/IP is fragmentation; it allows a single IP packet to be broken down into smaller segments. In 1996, attackers began to take advantage of that feature when they found that a packet broken down into fragments could add up to more than the allowed 65,536 bytes. Many operating systems didn't know what to do when they received an oversized packet, so they froze, crashed, or rebooted.

Source: ping of death



Edit: There's even an issue called "Ping flood":

Ping flood is a simple denial-of-service attack where the attacker/s overwhelms the victim with ICMP Echo Request (ping) packets. It is most successful if the attacker has more bandwidth than the victim (for instance an attacker with a DSL line and the victim on a dial-up modem).

The attacker hopes that the victim will respond with ICMP Echo Reply packets, thus consuming both outgoing bandwidth as well as incoming bandwidth. If the target system is slow enough, it is possible to consume enough of its CPU cycles for a user to notice a significant slowdown.

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afaik most modern OS are immune to Ping of Death –  Sathya Aug 4 '11 at 7:47
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"Modern" being "1998 or newer", for that matter. –  grawity Aug 4 '11 at 14:27
    
This is old school man. . . –  surfasb Aug 10 '11 at 6:12
    
Quite fortuitous that Ivan updated the other post today. the same day that the news that the ping of death is still lingering around –  Scott Chamberlain Aug 10 '11 at 6:32

You may try the tracert command, but that is probably blocked too.

The system administrators probably see ping as a security issue for some reason. AKA 99% of their users are inexperienced and have no use for the ping command, and the 1% that know it are most likely to be capable of compromising security.

Potentially, someone's malware might send pings to a remote server in order for that server to log the IP of the pinging machine.

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It can be used to change the BSOD to PSOD for people so inclined... –  Alex Waters Aug 4 '11 at 6:56
    
"Ping request could not find host google.com. Please check the name and try again" –  vinoth Aug 4 '11 at 7:03
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I'm getting this message: "'pink' is not recognized as an internal or external command, operable program or batch file." –  TFM Aug 4 '11 at 7:07
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@TFM Maybe your LAN cable is a different colour or you are on wireless? –  Linker3000 Aug 4 '11 at 7:55
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@TFM - you have to spraypaint the hard drive pink in order for the command to work. The optical drive has sensors that only trigger the correct message if the pink spectrometer is triggered... They do this so that you do not call the command unless it is absolutely necessary. Also, it lets any sys admins know that you have at some point tried to issue the pink command. –  Alex Waters Aug 4 '11 at 10:02

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