--- netdissect.h~	2005-09-29 00:46:46.000000000 -0700
+++ netdissect.h	2006-05-03 00:32:21.000000000 -0700
@@ -85,6 +85,7 @@
   int ndo_aflag;		/* translate network and broadcast addresses */
   int ndo_eflag;		/* print ethernet header */
   int ndo_fflag;		/* don't translate "foreign" IP address */
+  int ndo_Kflag;		/* don't check TCP checksums */
   int ndo_nflag;		/* leave addresses as numbers */
   int ndo_Nflag;		/* remove domains from printed host names */
   int ndo_qflag;		/* quick (shorter) output */
--- interface.h~	2005-09-29 00:46:45.000000000 -0700
+++ interface.h	2006-05-03 00:33:12.000000000 -0700
@@ -344,6 +344,7 @@
 
 #define eflag gndo->ndo_eflag 
 #define fflag gndo->ndo_fflag 
+#define Kflag gndo->ndo_Kflag 
 #define nflag gndo->ndo_nflag 
 #define Nflag gndo->ndo_Nflag 
 #define Oflag gndo->ndo_Oflag 
--- tcpdump.c~	2005-08-23 03:29:41.000000000 -0700
+++ tcpdump.c	2006-05-03 00:36:40.000000000 -0700
@@ -499,7 +499,7 @@
 
 	opterr = 0;
 	while (
-	    (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG "eE:fF:i:lLm:M:nNOpqr:Rs:StT:u" U_FLAG "vw:W:xXy:YZ:")) != -1)
+	    (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG "eE:fF:i:KlLm:M:nNOpqr:Rs:StT:u" U_FLAG "vw:W:xXy:YZ:")) != -1)
 		switch (op) {
 
 		case 'a':
@@ -637,6 +637,10 @@
 			++Nflag;
 			break;
 
+		case 'K':
+			++Kflag;
+			break;
+
 		case 'm':
 #ifdef LIBSMI
 		        if (smiLoadModule(optarg) == 0) {
@@ -1409,7 +1413,7 @@
 #endif /* WIN32 */
 #endif /* HAVE_PCAP_LIB_VERSION */
 	(void)fprintf(stderr,
-"Usage: %s [-aAd" D_FLAG "eflLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [-c count] [ -C file_size ]\n", program_name);
+"Usage: %s [-aAd" D_FLAG "efKlLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [-c count] [ -C file_size ]\n", program_name);
 	(void)fprintf(stderr,
 "\t\t[ -E algo:secret ] [ -F file ] [ -i interface ] [ -M secret ]\n");
 	(void)fprintf(stderr,
--- print-tcp.c~	2005-04-20 23:36:05.000000000 -0700
+++ print-tcp.c	2006-05-03 00:46:04.000000000 -0700
@@ -420,7 +420,7 @@
 		return;
 	}
 
-	if (IP_V(ip) == 4 && vflag && !fragmented) {
+	if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
 		u_int16_t sum, tcp_sum;
 		if (TTEST2(tp->th_sport, length)) {
 			sum = tcp_cksum(ip, tp, length);
@@ -434,7 +434,7 @@
 		}
 	}
 #ifdef INET6
-	if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
+	if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
 		u_int16_t sum,tcp_sum;
 		if (TTEST2(tp->th_sport, length)) {
 			sum = tcp6_cksum(ip6, tp, length);
--- tcpdump.1~	2005-09-05 02:14:37.000000000 -0700
+++ tcpdump.1	2006-05-03 00:52:30.000000000 -0700
@@ -29,7 +29,7 @@
 .na
 .B tcpdump
 [
-.B \-AdDeflLnNOpqRStuUvxX
+.B \-AdDefKlLnNOpqRStuUvxX
 ] [
 .B \-c
 .I count
@@ -378,6 +378,11 @@
 .I interface
 argument.
 .TP
+.B \-K
+Don't attempt to verify TCP checksums.  This is useful for interfaces
+that perform the TCP checksum calculation in hardware; otherwise,
+all outgoing TCP checksums will be flagged as bad.
+.TP
 .B \-l
 Make stdout line buffered.
 Useful if you want to see the data