Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: [OFFTOPIC?] Re: 2.2.x kernels missend odd-sized ICMP pa | Date | 12 Apr 1999 03:12:15 GMT |
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Followup to: <199904120151.VAA02001@sleipnir.valparaiso.cl> By author: Horst von Brand <vonbrand@sleipnir.valparaiso.cl> In newsgroup: linux.dev.kernel > > BTW, Comer's "Internetworking with TPC/IP, vol 1" tells me that the > checksum is computed by ones' complement sum of 16bit quantities in network > byte order and stored in network byte order (i.e., big endian), the > computation in ping.c:in_cksum is clearly in host format (little endian > around here). What gives? >
The reason one's complement (circular carry) is used is because it is endian-independent. The littleendian checksum stored in littleendian format is the same as the bigendian checksim stored in bigendian format.
-hpa -- "The user's computer downloads the ActiveX code and simulates a 'Blue Screen' crash, a generally benign event most users are familiar with and that would not necessarily arouse suspicions." -- Security exploit description on http://www.zks.net/p3/how.asp
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