Re: Can't ping local computers
From: Tron Thomas (tron.thomas_at_verizon.net)
Date: 19 Jul 2004 18:58:05 -0700
Allen Kistler <email@example.com> wrote in message news:<7ZcKc.37765$eH1.firstname.lastname@example.org>...
> Jerry Smiley wrote:
> > Check to make that each Linux box does not have a firewall setup that blocks
> > the icmp ping..
> It _is_ possible that you allow outgoing echo requests and incoming
> replies on both boxes (ping works to the router), but block incoming
> requests or outgoing replies (ping fails to each other).
> That's not likely for Windows unless you purchased a firewall or are
> testing SP2, since Windows only filters by tcp/udp port and ip protocol.
> The fact that both can talk to the router rules out wiring or netmask
> If you have arping (only works on local networks), you can try that from
> the Linux box. arping uses arp packets instead of icmp packets.
> tcpdump comes with most Linux distributions. If you run it on the Linux
> box when you try to ping one way or the other, it will provide you with
> a little more info.
> tcpdump -ni eth0 [... or something similar. It's really flexible.]
> 1. Do you get a successful arp (who-has and is-at packets)?
> 2. Does the icmp echo request go out? Is there an icmp reply?
I have arping. I tried /usr/sbin/arping [Macintosh Computer Name].
The result I got was:
arping: socket: Operation not permitted
I do not have tcpdump on my Linux system.
What do I need to do to see if I get a successful arp?
How do I test the icmp echo request and icmp reply?