In one of the system (Windows), if I ping to a particular public forum site, [lets say testsite.com here], then I get a request timed out message. However, if I just put that site address in the browser (used IE6, but its not specific) with http://, then the link works fine and the browser goes to the web page. What is it that the browser doing differently ?
+14
A:
The site may be behind a firewall that blocks ICMP requests (e.g., ping). HTTP requests that your browser sends out goes over TCP/IP.
Randy
2008-10-21 04:54:35
+5
A:
Ping sends an ICMP request package. The webserver can choose to ignore it and not respond, instead of responding with an ICMP response.
The web brower uses HTTP, which means it opens a TCP connection on port 80 by using a SYN/SYNACK/ACK exchange.
These two processes are completely different and independant, so you can enable/disable either independantly.
Laurent
2008-10-21 04:54:45
A:
It's not the browser. There could be a firewall between you and the server that's blocking the ping requests or the server simply may not be responding to pings. It's a common security measure.
Ates Goral
2008-10-21 04:55:41
A:
Ping (also known as ICMP) and the http protocol work completely differently and use different ports. Different devices/firewalls along the way may block ping but most allow http through.
IAmCodeMonkey
2008-10-21 04:55:51
A:
The browser uses the TCP/IP protocol to communicate with the server the HTTP requests, when you use ping, it uses the ICMP protocol and seems the server behind a firewall that drops the ICMP Echo Requests.
CMS
2008-10-21 04:56:10
+1
A:
A ping is essentially an "echo request" packet sent over IMCP (a protocol). The correct response to a ping is a handily "echo response" packet. However, if you send an echo response packet, people know you exist. Now, when you're running a web server, this isn't a big deal, but when you're running a standard desktop, you don't want people knowing you exist. The result is that many security-minded people will disable ping responses by default, even on server machines.
Samir Talwar
2008-10-21 04:56:27
A:
Ping packets, as others have stated, are a different type of packet than 'HTML' packets - Ping packets are ICMP/IP while HTML are TCP/IP. All kinds of stuff in between you and the website could choose to block the ICMP packets while allowing TCP packets through.
Claudiu
2008-10-21 05:46:39
Uh, stricly speaking, they're both running over IP. Ping uses ICMP over IP, and HTTP uses TCP over IP.
unwind
2008-10-21 06:03:28
my mistake... i recalled it being at the same level as IP, which it seems to be, but it does rely on IP.
Claudiu
2008-10-21 06:17:00
A:
Public servers often don't respond to ping requests. After all, people don't type ping testsite.com before they open their browser, right? So there's no real point to answer pings forthese sites. On the other hand:
A few years ago, a kid managed to simultaneously bring amazon.com and a couple of other such big sites down to thei knees during a couple of hours by having a few hundreds machines bomb them with loads of ping requests.
Since then, ping has not been considered that much friendly by admins.
Serge - appTranslator
2008-10-21 06:48:46
A:
which port i need to open that i can ping IP or my domain? Now i get connection timeout.
senzacionale
2010-08-20 17:13:34