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authorJason McIntyre <jmc@cvs.openbsd.org>2008-04-21 08:17:24 +0000
committerJason McIntyre <jmc@cvs.openbsd.org>2008-04-21 08:17:24 +0000
commit4432e4181cdf5c9dd50df0e1014f9d3aea79cfcd (patch)
tree195960cc19ecf2d04fcbb471fb59366144f714c3 /usr.sbin/tcpdump/tcpdump.8
parent2b828274cf3d4eb5e3976307960617ec5d5e6b99 (diff)
add a short section on checksum offloading, based on a diff
from Alf Schlichting; help/ok henning
Diffstat (limited to 'usr.sbin/tcpdump/tcpdump.8')
-rw-r--r--usr.sbin/tcpdump/tcpdump.810
1 files changed, 8 insertions, 2 deletions
diff --git a/usr.sbin/tcpdump/tcpdump.8 b/usr.sbin/tcpdump/tcpdump.8
index a1a8585ad5a..085cf8ed35a 100644
--- a/usr.sbin/tcpdump/tcpdump.8
+++ b/usr.sbin/tcpdump/tcpdump.8
@@ -1,4 +1,4 @@
-.\" $OpenBSD: tcpdump.8,v 1.66 2008/04/18 21:35:11 djm Exp $
+.\" $OpenBSD: tcpdump.8,v 1.67 2008/04/21 08:17:23 jmc Exp $
.\"
.\" Copyright (c) 1987, 1988, 1989, 1990, 1991, 1992, 1994, 1995, 1996
.\" The Regents of the University of California. All rights reserved.
@@ -19,7 +19,7 @@
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
-.Dd $Mdocdate: April 18 2008 $
+.Dd $Mdocdate: April 21 2008 $
.Dt TCPDUMP 8
.Os
.Sh NAME
@@ -1795,6 +1795,12 @@ Ethernet interface removed the packet from the wire and when the kernel
serviced the
.Dq new packet
interrupt.
+.Ss IP Checksum Offload
+Some network cards support IP checksum offload.
+Packet headers for such interfaces erroneously indicate a bad checksum,
+since the checksum is not calculated until after
+.Nm
+sees the packet.
.Sh SEE ALSO
.\" traffic(1C), nit(4P),
.Xr ethers 3 ,