Date: Sat, 12 Feb 2005 11:57:05 -0500 From: Ean Kingston <ean@hedron.org> To: freebsd-questions@freebsd.org Cc: ann kok <annkok2001@yahoo.com> Subject: Re: ping question Message-ID: <200502121157.05950.ean@hedron.org> In-Reply-To: <20050212165032.1637.qmail@web52003.mail.yahoo.com> References: <20050212165032.1637.qmail@web52003.mail.yahoo.com>
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On February 12, 2005 11:50 am, ann kok wrote: > Hi all > > I ping from redhat to cisco router and freebsd router > but I don't understand ttl (time to live) ttl is 'time-to-live' it is a counter. Every router that the ping packet goes through subtracts 1 from the ttl value. When it reaches 0 (zero), the router that got the zero replies with a 'ttl exceeded message'. If the ping packet reaches it's destination before the ttl goes to zero, it replies with a 'ping reply'. This helps with diagnosis of network configuration issues. > Cisco router has ttl=251 and freebsd router has 58 > Does it set by the router itself? > Can I change it in freebsd? You control the ttl value from the place you send the ping from (in your description the RedHat system). When using ping from FreeBSD the -m parameter is used to set the initial value. I believe the initial value can be anything from 0 to 255. The default varies from system to system but the most common is 255. > > Thank you > [cut sample ping output] -- Ean Kingston E-Mail: ean AT hedron DOT org URL: http://www.hedron.org/
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