--- netcat-4.0.20061122/usr.bin/nc/nc.1

+++ netcat-4.0.20061122/usr.bin/nc/nc.1

@@ -146,6 +146,8 @@ instead of sequentially within a range or in the order that the system

 assigns them.

 .It Fl S

 Enables the RFC 2385 TCP MD5 signature option.

+.Ar NOTE:

+This option is supported under OpenBSD, but not under Linux now.

 .It Fl s Ar source_ip_address

 Specifies the IP of the interface which is used to send the packets.

 It is an error to use this option in conjunction with the

--- netcat-4.0.20061122/usr.bin/nc/netcat.c

+++ netcat-4.0.20061122/usr.bin/nc/netcat.c

@@ -56,6 +56,14 @@

 #include "atomicio.h"

 #include <time.h>

+#if defined(TCP_MD5SIG)

+#define HAVE_TCP_MD5SIG 1

+#endif

+

+#if defined(SO_JUMBO)

+#define HAVE_SO_JUMBO 1

+#endif

+

 #ifndef SUN_LEN

 #define SUN_LEN(su) \

 	(sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))

@@ -67,7 +75,9 @@

 /* Command Line Options */

 int	dflag;					/* detached, no stdin */

 unsigned int iflag;				/* Interval Flag */

+#if defined(HAVE_SO_JUMBO)

 int	jflag;					/* use jumbo frames if we can */

+#endif

 int	kflag;					/* More than one connect */

 int	lflag;					/* Bind to local port */

 int	nflag;					/* Don't do name look up */

@@ -81,7 +91,9 @@ int	vflag;					/* Verbosity */

 int	xflag;					/* Socks proxy */

 int	zflag;					/* Port Scan Flag */

 int	Dflag;					/* sodebug */

+#if defined(HAVE_TCP_MD5SIG)

 int	Sflag;					/* TCP MD5 signature option */

+#endif

 int	Tflag = -1;				/* IP Type of Service */

 int timeout = -1;

@@ -160,7 +172,11 @@ main(int argc, char *argv[])

 				errx(1, "interval %s: %s", errstr, optarg);

 			break;

 		case 'j':

+#if defined(HAVE_SO_JUMBO)

 			jflag = 1;

+#else

+			errx(1, "-j requires SO_JUMBO kernel support that's missing under Linux now");

+#endif

 			break;

 		case 'k':

 			kflag = 1;

@@ -211,7 +227,11 @@ main(int argc, char *argv[])

 			Dflag = 1;

 			break;

 		case 'S':

+#if defined(HAVE_TCP_MD5SIG)

 			Sflag = 1;

+#else

+			errx(1, "-S requires TCP_MD5SIG kernel support that's missing under Linux now");

+#endif

 			break;

 		case 'T':

 			Tflag = parse_iptos(optarg);

@@ -311,7 +331,11 @@ main(int argc, char *argv[])

 				struct sockaddr_storage z;

 				len = sizeof(z);

+#if defined(HAVE_SO_JUMBO)

 				plen = jflag ? 8192 : 1024;

+#else

+				plen = sizeof(buf);

+#endif

 				rv = recvfrom(s, buf, plen, MSG_PEEK,

 				    (struct sockaddr *)&z, &len);

 				if (rv < 0)

@@ -608,7 +632,11 @@ readwrite(int nfd)

 	int lfd = fileno(stdout);

 	int plen;

+#if defined(HAVE_SO_JUMBO)

 	plen = jflag ? 8192 : 1024;

+#else

+	plen = sizeof(buf);

+#endif

 	/* Setup Network FD */

 	pfd[0].fd = nfd;

@@ -772,26 +800,32 @@ set_common_sockopts(int s)

 {

 	int x = 1;

+#if defined(HAVE_TCP_MD5SIG)

 	if (Sflag) {

 		if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,

 			&x, sizeof(x)) == -1)

 			err(1, NULL);

 	}

+#endif

 	if (Dflag) {

 		if (setsockopt(s, SOL_SOCKET, SO_DEBUG,

 			&x, sizeof(x)) == -1)

 			err(1, NULL);

 	}

+#if defined(HAVE_SO_JUMBO)

 	if (jflag) {

 		if (setsockopt(s, SOL_SOCKET, SO_JUMBO,

 			&x, sizeof(x)) == -1)

 			err(1, NULL);

 	}

+#endif

 	if (Tflag != -1) {

 		if (setsockopt(s, IPPROTO_IP, IP_TOS,

 		    &Tflag, sizeof(Tflag)) == -1)

 			err(1, "set IP ToS");

 	}

+

+	return;

 }

 int

@@ -827,9 +861,13 @@ help(void)

 	\t-n		Suppress name/port resolutions\n\

 	\t-P proxyuser\tUsername for proxy authentication\n\

 	\t-p port\t	Specify local port for remote connects\n\

-	\t-r		Randomize remote ports\n\

-	\t-S		Enable the TCP MD5 signature option\n\

-	\t-s addr\t	Local source address\n\

+	\t-r		Randomize remote ports\n"

+#if defined (HAVE_TCP_MD5SIG)

+"	\t-S		Enable the TCP MD5 signature option\n"

+#else

+"	\t-S		Enable the TCP MD5 signature option (BSD only!)\n"

+#endif

+"	\t-s addr\t	Local source address\n\

 	\t-T ToS\t	Set IP Type of Service\n\

 	\t-t		Answer TELNET negotiation\n\

 	\t-U		Use UNIX domain socket\n\