Date: Mon, 28 Nov 2005 21:49:31 -0500 From: Kris Kennaway <kris@obsecurity.org> To: John Palmer <drgnut@hotmail.com> Cc: freebsd-net@freebsd.org, freebsd-questions@freebsd.org Subject: Re: bad udp cksum 26ff! Message-ID: <20051129024931.GA34483@xor.obsecurity.org> In-Reply-To: <BAY107-F18639103D61657857C3994D1480@phx.gbl> References: <BAY107-F18639103D61657857C3994D1480@phx.gbl>
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--1yeeQ81UyVL57Vl7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 28, 2005 at 10:46:38AM -0800, John Palmer wrote: > I am running FreeBSD 5.4 p8. I did a tcpdump -vv -i em0. The output=20 > produced > a "bad udp cksum" with my DNS server. Does anyone know what it means? O= r,=20 > how I can > correct the problem? If your NIC is doing checksum offload, tcpdump on the host won't see the right checksum, since it's only generated on the way out the door. Run tcpdump on another host on the network to verify whether it's correct on the wire. Kris --1yeeQ81UyVL57Vl7 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDi8G6Wry0BWjoQKURAvb0AKCkySq7b4u3NgG4vYUZy35LRfo4RwCfVziD Hhqc7Z2Htd2mF4cKoRbeRzM= =mTHk -----END PGP SIGNATURE----- --1yeeQ81UyVL57Vl7--
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