Date: Sun, 28 Sep 2003 19:15:00 +0200 From: "Dambielle Yannick" <yannick.dambielle@free.fr> To: "Robert Watson" <rwatson@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: tcpdump - tun/tap virtual interfaces Message-ID: <001401c385e4$0cfde770$3fc64352@shibuya> References: <Pine.NEB.3.96L.1030928123753.20493E-100000@fledge.watson.org>
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----- Original Message -----
From: "Robert Watson" <rwatson@freebsd.org>
To: "Dambielle Yannick" <yannick.dambielle@free.fr>
Cc: <freebsd-net@freebsd.org>
Sent: Sunday, September 28, 2003 6:40 PM
Subject: Re: tcpdump - tun/tap virtual interfaces
>
> On Sun, 28 Sep 2003, Dambielle Yannick wrote:
>
> > I've tried to dump some paquets sent to a virtual interface without any
> > success for a couple of hours so I ask for some helps to the list. I
> > use a FreeBSD 5.0, my kernel has been rebuilt and installed with the
> > following option in order to use a tap virtual interface : device tap
> > The virtual interface has been created (tap0) and I've attached the IP
> > adress 10.0.0.1. It seems ok, I can see it with ifconfig. All the tests
> > are local tests. While I ping 10.0.0.1 (paquets are sent and not lost),
> > I laught a tcpdump -i tap0 from another shell... Nothing is dumped
> > (?!)... Well, if some of you has an idea, I'll be very happy.
>
> Do you see anything when you ping the broadcast address or other foreign
> address of the tap interface? Packets delivered to local IP addresses
> generally don't go out an interface.
>
> Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
> robert@fledge.watson.org Network Associates Laboratories
>
When I try to ping the broadcast address I have the following results:
# ping 10.0.0.255
ping: sendto: Permission denied
...
Bellow is how I do for setting up a virtual interface :
# echo 1 > /dev/tap1
# ifconfig tap1 up
# ifconfig tap1 inet 10.0.10.1/24 add
# ifconfig <-- show me that tap1 has 10.0.10.1 attached and is also running
On the first shell, I ping 10.0.10.1
# ping 10.0.10.1
64 butes from 10.0.10.1: icmp_seq=0 ttl=64 time=0.137ms
64 butes from 10.0.10.1: icmp_seq=0 ttl=64 time=0.137ms
...
On a second shell, I try to dump
# tcpdump -i tap1
That wait... that wait... Nothing comes :/
Let's try to ping the broadcast address
# ping 10.0.10.255
ping: sendto: Permission denied, same as before
...
Well, any ideas are welcome.
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