pop quiz: icmp ping & linux

[Brecht Vermeulen]

Douglas,

well, rfc 792 says :
   Sequence Number
 
 
[Page 14]
^L
 
September 1981
RFC 792
 
 
 
      If code = 0, a sequence number to aid in matching echos and
      replies, may be zero.
 
   Description
 
      The data received in the echo message must be returned in the echo
      reply message.             
      The identifier and sequence number may be used by the echo sender
      to aid in matching the replies with the echo requests.  For
      example, the identifier might be used like a port in TCP or UDP to
      identify a session, and the sequence number might be incremented
      on each echo request sent.  The echoer returns these same values
      in the echo reply.
 
      Code 0 may be received from a gateway or a
host.                          


so, the receiver has to return the *exact* content, and the sender can
use what it sent, so it doesn't matter how you specify the number, the
sender knows what type it has sent.

best regards,
Brecht





"Douglas S. J. De Couto" wrote:
> 
> pop quiz:
> 
> is it true that sequence numbers in ping packets (icmp echo) must be
> in network byte order?
> 
> factiod:
> 
> OpenBSD puts them in net byte order, Linux does not.
> 
> d
> 
> --
> Douglas S. J. De Couto    decouto at lcs.mit.edu