Red Hat Bugzilla – Bug 115333
ping flood is hardly a flood
Last modified: 2015-03-04 20:13:28 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040130 Description of problem: ping flood only sends about 70 packets/second (+/- 20), even though the man page says it should do at least 100 packets/second. This occurs even when pinging the loopback address, where response whould be almost instantaneous. If I run tcpdump and watch the packets, the icmp packets replies occur quickly and then ping waits to send another request. This is also evident from the ping output which has very low ping times. [root@turbo andrew]# time ping -f localhost PING localhost.localdomain (127.0.0.1) 56(84) bytes of data. --- localhost.localdomain ping statistics --- 1530 packets transmitted, 1530 received, 0% packet loss, time 19420ms rtt min/avg/max/mdev = 0.036/0.044/0.055/0.005 ms, pipe 2, ipg/ewma 12.701/0.043 ms real 0m19.427s user 0m0.000s sys 0m0.000s Version-Release number of selected component (if applicable): 20020927-11 How reproducible: Always Steps to Reproduce: time ping -f localhost Actual Results: packets per second is less than 100 Expected Results: packets per second should be at least 100 (according to man page) based on the response for pinging localhost, it should have done ~20000 packets/second.
The man page says flood ping does up to 100 packages per second, not more than 100: -f Flood ping. For every ECHO_REQUEST sent a period ââ.ââ is printed, while for ever ECHO_REPLY received a backspace is printed. This provides a rapid display of how many packets are being dropped. If interval is not given, it sets interval to zero and outputs packets as fast as they come back or one hun- dred times per second, whichever is more. Only the super-user may use this option with zero interval. This new behaviour is wanted as flood ping was know to be used to "shutdown" remote systems by sending as much packages as possible. This is now not possible anymore so easily with ping. Read ya, Phil
> The man page says flood ping does up to 100 packages per second, not > more than 100: this is certainly false. The man page says: > outputs packets as fast as they come back or one hundred times per > second, whichever is more. "as fast as they come back" is more than "one hundred times per second" and should be used, according to the man page.
Ups, true, but then the manpage needs to be corrected at some point as the code clearly limits to a maximum of 100 packages per second. Read ya, Phil