Believe it or not, this is an OLD bug in ping...  search the archives -- I
analyzed and posted the info quite a while back (over a year IIRC).  The
problem can happen when your link is quite busy and ping response are
delayed longer than the ping timeout value...  it's a race condition in
ping...  look for other traffic on the link.

HTH,
Pierre

On Sat, 7 Sep 2002 10:07:51 -0400 Randy Kramer <[EMAIL PROTECTED]> wrote:

> Background: In conjunction with running fetchmail every 10 minutes, I 
> ping my ISP before running fetchmail.  (My script is set up so that 
> when I get "0% packet loss" on a sequence of 4 pings, it runs fetchmail 
> (and then sendmail -q to kick the queue).)
> 
> Fairly often (several times a day?), I get one or more pings with an 
> error message like:
> 
> wrong data byte #0 should be 0x59 but was ... (see complete ping 
> response, below:)
> 
> Complete ping response:
> 
> PING 206.245.176.211 (206.245.176.211): 56 octets data
> 64 octets from 206.245.176.211: icmp_seq=0 ttl=122 time=1099.4 ms
> wrong data byte #0 should be 0x59 but was 0x5858 ff 79 3d 79 6b a 0 
> ��������8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 
> 20 21 22 23 24 25 26 27 
> ��������28 29 2a 2b 2c 2d 2e 2f 
> 64 octets from 206.245.176.211: icmp_seq=1 ttl=122 time=268.4 ms
> 64 octets from 206.245.176.211: icmp_seq=2 ttl=122 time=283.4 ms
> 64 octets from 206.245.176.211: icmp_seq=3 ttl=122 time=251.6 ms
> 
> In the above case, the wrong data byte occurred for only one of the 
> pings -- in other cases it occurs for 2, 3, or 4 (all of the) pings, 
> but usually (always?) for the earliest pings rather than the last pings.
> 
> Questions: What is this telling me and/or how does it occur?  This box  
> is on a coax LAN, so I suppose it could be seeing TCP/IP traffic not 
> meant for it -- is that likely to be the problem, or noise, or ???  
> What can I do to fix it?  (I can't easily convert the LAN to TP as I'd 
> have to run new cable which I prefer not to do in the near future -- 
> maybe in a few years.)
> 
> I suppose I should run a sniffer on the network, but there really 
> should not be a lot of traffic.  Can anybody recommend a sniffer that 
> comes with Mandrake 7.2 or 8.2 (i.e., so I can install from an rpm)?
> 
> thanks,
> Randy Kramer
> 
> 
> 

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