--- a/configure.in
+++ b/configure.in
@@ -84,15 +84,26 @@
 dnl #######################
 dnl Checks for header files
 dnl #######################
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS(sys/time.h sys/stat.h unistd.h strings.h fcntl.h netinet/ip6.h)
+AC_CHECK_HEADERS(sys/time.h sys/stat.h unistd.h strings.h fcntl.h)
 
 dnl BSD/OS Seems to not have a good ethernet header, so we gotta wing it
 AC_CHECK_HEADERS(net/if.h net/ethernet.h netinet/if_ether.h net/ppp_defs.h)
 
+AC_ARG_ENABLE( ipv6, [ AC_HELP_STRING([--enable-ipv6], [s use IPv6?]) ], ip6=$enableval )
+if test "$ip6" = "yes"
+then
+	AC_CHECK_HEADER(netinet/ip6.h, , [AC_MSG_ERROR([I couldn't find netinet/ip6.h though you asked for ipv6 support.])] )
+elif test "$ip6" != "no"
+then
+	AC_CHECK_HEADER(netinet/ip6.h)
+
+fi
+
+
 dnl #############################################################
 dnl Checks for typedefs, structures, and compiler characteristics
 dnl #############################################################
 AC_C_CONST
 AC_TYPE_SIZE_T
@@ -147,34 +158,11 @@
   If you already have... then please rerun configure with the option
     --with-pcap-lib=DIR
   with "DIR" being where libpcap is found.])
 ])
 
-dnl look for dbopen for tcpprof
-TCPPROF=""
-LD_TCPPROF=""
-AC_CHECK_LIB(c, dbopen, [ TCPPROF=tcpprof ], [
- AC_CHECK_LIB(db1, dbopen, [
-  TCPPROF=tcpprof
-  LD_TCPPROF="-ldb1"
-  AC_DEFINE(USE_DB1_LIBRARY, 1, [ Use the sleepycat DB library. ])
-  ], [
-  AC_MSG_WARN([
-
-  *** WARNING ***
-  I couldn't locate the Berkeley DB library.  The extra utility
-  "tcpprof" will not be built.  THIS IS OK!!!  "tcpstat" will
-  continue to be built as if this never happened.
-
-  If you wish to use the extra "tcpprof" program, please install
-  the Berkeley DB library from:
-      ftp://ftp.cs.berkeley.edu/ucb/4bsd/db.tar.gz
-    ])
-  ])
-])
 AC_SUBST(TCPPROF)
-AC_SUBST(LD_TCPPROF)
 AC_SUBST(MATHLIB)
 
 AC_CONFIG_FILES([
 Makefile
 doc/Makefile
--- a/lib/process.c
+++ b/lib/process.c
@@ -230,12 +230,12 @@
  *   calls a user function pointing to the data
  *
  * XXX: filter is not used.  capture_seconds also isn't, but snoop is
  *	always read from a file.
  */
-int get_snoop_data(char *fname, char *filter, int flags,
-	Double capture_seconds, void (*hook)(packet_data *, void **),
+int get_snoop_data(char *fname,  char *filter __attribute__((unused)), int flags,
+	Double capture_seconds __attribute__((unused)), void (*hook)(packet_data *, void **),
 	void **args) {
 
 	u_char *packet;
 	int fd, len, blen, ret = 0;
 	struct snoop_file_header	fh;
--- a/lib/tcpseq.c
+++ b/lib/tcpseq.c
@@ -54,11 +54,10 @@
 	u_char	flags;
 	struct tcpseq_ha test_ha;
 	struct tcphdr *tp = NULL;
 	struct ip *ip;
 #ifdef INET6
-	int is_ip6 = 0;
 	struct ip6_hdr *ip6;
 
 	ip6 = (struct ip6_hdr *) &pd->data.ip6.hdr;
 	if (is_ip6_packet(pd))
 		tp= &(pd->data.ip6.body.tcphdr);
--- a/src/catpcap.c
+++ b/src/catpcap.c
@@ -50,11 +50,11 @@
 	if (c == ' ') return c;
 	if ((u_char)c > 0xa1 && SHOW_HIGH_BIT) return c;
 	return '.';
 }
 
-void proc_pcap(u_char *user, const struct pcap_pkthdr *h, const u_char *p) {
+void proc_pcap(u_char *user __attribute__((unused)), const struct pcap_pkthdr *h, const u_char *p) {
 	u_int length = h->caplen, i, j, k, step;
 	u_char *r, *s;
 	char c;
 
 	r = (u_char *)p;
@@ -90,11 +90,11 @@
 }
 /*
  * process_file() takes the output of tcpdump, saves packets, and displays
  * statistics
  */
-void process_file(char *fname, u_int unused) {
+void process_file(char *fname, u_int unused __attribute__((unused))) {
 	int run = 1, i;
 	pcap_t	*pd;
 	char	ebuf[PCAP_ERRBUF_SIZE];
 	struct bpf_program	bpf_prog;
 
--- a/src/dump.c
+++ b/src/dump.c
@@ -37,21 +37,21 @@
 char filterexpr[BUF_SIZ]	= "";
 int	get_tcp_flags		= 0;
 int	what_to_show		= 0;
 int	packet_number		= 0;
 
-void my_hook(packet_data *pd, void **args) {
+void my_hook(packet_data *pd) {
 	printf("PACKET NUMBER: %d\n", ++packet_number);
 	print_packet(pd, what_to_show);
 	printf("-------------------\n");
 }
 
 /*
  * process_file() takes the output of tcpdump, saves packets, and displays
  * statistics
  */
-void process_file(char *fname, u_int unused) {
+void process_file(char *fname, u_int unused __attribute__((unused))) {
         get_dump_data(fname, filterexpr, get_tcp_flags,
 		-1.0, my_hook, NULL);
 }
 
 int parse_show_types(char *in) {
--- a/src/tcpstat.c
+++ b/src/tcpstat.c
@@ -421,11 +421,11 @@
 }
 
 /*
  * process_file() gets the data, and then displays the statistics
  */
-void process_file(char *fname, u_int unused) {
+void process_file(char *fname, u_int unused __attribute__((unused))) {
 	void		*argv[2];
 	statistics	stats;
 	Double		x;
 
 	signal(SIGUSR1, catch_signal);