From owner-freebsd-stable  Wed May  9 17:31:54 2001
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Date: Wed, 9 May 2001 17:31:44 -0700 (PDT)
From: Tom <tom@uniserve.com>
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To: Chris <chris@chrisland.net>
Cc: stable@freebsd.org
Subject: Re: ping reply and ttl
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On Thu, 10 May 2001, Chris wrote:

> Hi,
> 
> just upgraded to 4.3-STABLE #2.
> when ping to this machine:
> 64 bytes from x.x.x.x: icmp_seq=0 ttl=59 time=26.476 ms
> 64 bytes from x.x.x.x: icmp_seq=1 ttl=59 time=26.393 ms
> 
> before upgrading:
> 64 bytes from x.x.x.x: icmp_seq=0 ttl=250 time=26.632 ms
> 64 bytes from x.x.x.x: icmp_seq=1 ttl=250 time=44.669 ms
> 
> looking around the source I found that in ip_icmp.c, "net.inet.ip.ttl"
> will be picked up since last commit.
> 
> Any reasons, well, benefits, behind this commit?  I get used to the old
> result and was alerted on the ttl values if something was wrong.  Now I
> cannot rely on this value.

  What do you mean?  They are the exact same result.  The first was done
with a machine with a ttl of 64 (64-5=59), and the second had a ttl of 255
(255-5=250).


> Also in manpage of ping, it reads:
> 
>      In normal operation ping prints the ttl value from the packet it
> re-
>      ceives.  When a remote system receives a ping packet, it can do one
> of
>      three things with the TTL field in its response:
> 
>      o   Set it to 255; this is what current BSD systems do.  In this
> case the
>          TTL value in the received packet will be 255 minus the number
> of
>          routers in the path from the remote system to the pinging host.
> 
> time to change?

  Seems accurate to me.  The default of 255 can be changed with a sysctl
now though.

> 
> Thanks.
> Chris


Tom


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