Messages in this thread |  | | | From | kuznet@ms2 ... | | Subject | Re: Flood ping | | Date | Fri, 25 Sep 1998 19:53:52 +0400 (MSK DST) |
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Hello!
> Cute.. Where do I get a new ping? What was the nature of this bug? How was > it worked around? I'm curious..
When ping sends echo request via loopback, it receives TWO packets back: echo request and echo reply. In "flood" mode it sends next packet, as only it received something (in this case request!)
In ~2.1.79, ICMP_FILTER option was introduced, and I choose default setting for filter to kill echo (and timestamp) requests. It repaired ping, but broke lots of icmp applets, sort of icmpinfo etc. Well, and it really was stupid default. 8) Now it defualts to filtering nothing.
There are two fixes to ping:
- The first is the simplest: to use ICMP_FILTER option to filter out echo requests.
- The second is more correct (particularly, it works for all Linux kernels) but it is more complicated: namely, ping should parse icmp packet, and filter out packets destined not to it before sending new echo request.
Alexey
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