diff --git a/configfile.c b/configfile.c
index 73ff3ae..1314bb3 100644
--- a/configfile.c
+++ b/configfile.c
@@ -36,13 +36,13 @@
 struct conf_section {
 	struct list_head list;
 	struct list_head tupel_list;
-	char *name;
+	const char *name;
 };
 
 struct conf_tupel {
 	struct list_head list;
-	char *option;
-	char *parameter;
+	const char *option;
+	const char *parameter;
 };
 
 static LIST_HEAD(config_list);
@@ -142,6 +142,23 @@ int config_parse(const char *config)
 	return 0;
 }
 
+void config_free(void)
+{
+	struct conf_section *section, *section_tmp;
+	struct conf_tupel *tupel, *tupel_tmp;
+
+	list_for_each_entry_safe(section, section_tmp, &config_list, list) {
+		list_for_each_entry_safe(tupel, tupel_tmp, &section->tupel_list, list) {
+			list_del(&tupel->list);
+			free((char *)tupel->option);
+			free((char *)tupel->parameter);
+			free(tupel);
+		}
+		list_del(&section->list);
+		free(section);
+	}
+}
+
 static struct conf_section * config_get_section(const char *name)
 {
 	struct conf_section *section;
@@ -153,7 +170,7 @@ static struct conf_section * config_get_section(const char *name)
 	return NULL;
 }
 
-char * config_get_string(const char *section_str, const char *option, char *def)
+const char * config_get_string(const char *section_str, const char *option, const char *def)
 {
 	struct conf_section *section = config_get_section(section_str);
 	if (section != NULL) {
@@ -172,7 +189,7 @@ char * config_get_string(const char *section_str, const char *option, char *def)
 
 int config_get_int(const char *section, const char *option, int def)
 {
-	char *ret = config_get_string(section, option, NULL);
+	const char *ret = config_get_string(section, option, NULL);
 	if (ret == NULL) {
 		log_print(LOG_WARN, "config [%s:%s] not found, using default: '%d'",
 			section, option, def);
diff --git a/configfile.h b/configfile.h
index 6528459..9a2b669 100644
--- a/configfile.h
+++ b/configfile.h
@@ -1,11 +1,10 @@
 #ifndef _CONFIG_H_
 #define _CONFIG_H_
 
-#include <netinet/in.h>
-
 int config_parse(const char *config);
+void config_free(void);
 
-char * config_get_string(const char *section_str, const char *option, char *def);
+const char * config_get_string(const char *section_str, const char *option, const char *def);
 
 int config_get_int(const char *section, const char *option, int def);
 
diff --git a/conntrack.c b/conntrack.c
index 93b026b..1013f8f 100644
--- a/conntrack.c
+++ b/conntrack.c
@@ -63,7 +63,7 @@ struct hash_table * conntrack_get_hash(void)
 
 int conntrack_init(void)
 {
-	char *mask = config_get_string("global", "netmask", DEFAULT_NETMASK);
+	const char *mask = config_get_string("global", "netmask", DEFAULT_NETMASK);
 	if (inet_aton(mask, &netmask) == 0) {
 		log_print(LOG_ERROR, "conntrack_init: invalid netmask");
 		return -1;
@@ -116,6 +116,9 @@ int conntrack_start_event_thread(void)
 
 int conntrack_close(void)
 {
+	if (ct_thread)
+		pthread_cancel(ct_thread);
+
 	destroy_hash(table[1]);
 	destroy_hash(table[0]);
 
diff --git a/ctstats.c b/ctstats.c
index b448ee1..c9ec8d6 100644
--- a/ctstats.c
+++ b/ctstats.c
@@ -4,6 +4,8 @@
 
 #include <string.h>
 #include <getopt.h>
+#include <signal.h>
+#include <errno.h>
 
 #include "configfile.h"
 #include "conntrack.h"
@@ -21,6 +23,13 @@ static struct option opts[] = {
 	{0, 0, 0, 0}
 };
 
+static int sig_received = 0;
+
+static void my_sighandler(int s)
+{
+	sig_received = 1;
+}
+
 int main(int argc, char *argv[])
 {
 	char *config = DEFAULT_CONFIG;
@@ -72,29 +81,41 @@ int main(int argc, char *argv[])
 	}
 
 	/* check logfile */
-	char *logfile = config_get_string("global", "logfile", DEFAULT_LOGFILE);
+	const char *logfile = config_get_string("global", "logfile", DEFAULT_LOGFILE);
 	if (logfile != NULL && debug == 0) {
 		/* start logging */
-		if (!log_init(logfile))
+		if (log_init(logfile))
 			exit(1);
 
 		/* zum daemon mutieren */
 		daemon(-1, 0);
 	}
 
+	log_print(LOG_EVERYTIME, "ctstats started (pid: %d)", getpid());
+
+	signal(SIGINT, my_sighandler);
+	signal(SIGTERM, my_sighandler);
+
 	/* start event listener */
 	conntrack_start_event_thread();
 
 	int intervall = config_get_int("global", "intervall", DEFAULT_INTERVALL);
-	while (1) {
-		sleep(intervall);
 
-		/* parse hashes, fill database */
+	struct timeval tv;
+	tv.tv_sec = intervall;
+	tv.tv_usec = 0;
+
+	while (sig_received == 0) {
+		select(0, NULL, NULL, NULL, &tv);
+		errno = 0;
+
+		tv.tv_sec = intervall;
+		tv.tv_usec = 0;
 		database_analyse();
 	}
 
-	/* how to stop? */
 	database_close();
 	conntrack_close();
+	log_close();
 	return 0;
 }
diff --git a/database.c b/database.c
index eac8fd3..8a97040 100644
--- a/database.c
+++ b/database.c
@@ -13,7 +13,7 @@
 
 static MYSQL *dbh;
 
-static void purge_hash_cb(struct hash_entry *entry, void *privdata)
+static void purge_hash_cb(const struct hash_entry *entry, void *privdata)
 {
 	int long *now = (long *)privdata;
 	char query[256];
@@ -50,9 +50,9 @@ int database_init(void)
 		return -1;
 	}
 
-	char *hostname = config_get_string("mysql", "hostname", NULL);
-	char *username = config_get_string("mysql", "username", NULL);
-	char *password = config_get_string("mysql", "password", NULL);
+	const char *hostname = config_get_string("mysql", "hostname", NULL);
+	const char *username = config_get_string("mysql", "username", NULL);
+	const char *password = config_get_string("mysql", "password", NULL);
 	MYSQL *ret = mysql_real_connect(dbh, hostname, username, password, NULL, 0, NULL, 0);
 	if (ret != dbh) {
 		log_print(LOG_ERROR, "database_init: mysql_real_connect(): %s", mysql_error(dbh));
@@ -60,7 +60,7 @@ int database_init(void)
 		return -1;
 	}
 
-	char *database = config_get_string("mysql", "database", NULL);
+	const char *database = config_get_string("mysql", "database", NULL);
 	if (mysql_select_db(dbh, database) != 0) {
 		log_print(LOG_ERROR, "database_init: mysql_select_db(): %s", mysql_error(dbh));
 		mysql_close(dbh);
diff --git a/hashtable.c b/hashtable.c
index 353ee16..30c8fde 100644
--- a/hashtable.c
+++ b/hashtable.c
@@ -41,7 +41,7 @@ struct hash_table * create_hash(uint32_t buckets)
 }
 
 void purge_hash(struct hash_table *table,
-		void (*callback)(struct hash_entry *entry, void *privdata),
+		void (*callback)(const struct hash_entry *entry, void *privdata),
 		void *privdata)
 {
 	uint32_t i;
@@ -71,7 +71,7 @@ void destroy_hash(struct hash_table *table)
 	free(table);
 }
 
-static uint32_t calc_hashkey(struct hash_entry *entry, uint32_t initval)
+static uint32_t calc_hashkey(const struct hash_entry *entry, uint32_t initval)
 {
 	uint32_t a = entry->src_ip;
 	uint32_t b = entry->protonum;
@@ -86,7 +86,7 @@ static uint32_t calc_hashkey(struct hash_entry *entry, uint32_t initval)
 	return c;
 }
 
-static int cmp_entry(struct hash_entry *a, struct hash_entry *b)
+static int cmp_entry(const struct hash_entry *a, const struct hash_entry *b)
 {
 	return (a->src_ip ^ b->src_ip) |
 		(a->protonum ^ b->protonum) |
diff --git a/hashtable.h b/hashtable.h
index 06ddbc2..fdb23bc 100644
--- a/hashtable.h
+++ b/hashtable.h
@@ -25,7 +25,7 @@ struct hash_table {
 struct hash_table * create_hash(uint32_t buckets);
 
 void purge_hash(struct hash_table *table,
-		void (*callback)(struct hash_entry *entry, void *privdata),
+		void (*callback)(const struct hash_entry *entry, void *privdata),
 		void *privdata);
 
 void destroy_hash(struct hash_table *table);
diff --git a/logging.c b/logging.c
index d4fd706..61dcfcf 100644
--- a/logging.c
+++ b/logging.c
@@ -29,75 +29,74 @@
 #define BUFSIZE 8192
 
 static FILE *log_fd = NULL;
+static int log_prio = LOG_EVERYTIME;
 static char *buffer = NULL;
 
-void log_print(int prio, const char *fmt, ...)
+int log_print(int prio, const char *fmt, ...)
 {
 	va_list az;
-	int len;
+	int len = 0, retval;
+
+	if (prio < log_prio)
+		return 0;
 
 	if (buffer == NULL) {
 		buffer = malloc(BUFSIZE);
 		if (buffer == NULL) {
-			fprintf(stderr, "log_print: out of memory\nBailing out!\n");
-			exit(-1);
+			fprintf(stderr, "log_print(): out of memory\n");
+			return -1;
 		}
 	}
 
+	if (log_fd != NULL) {
+		time_t  tzgr;
+		time(&tzgr);
+
+		len += strftime(buffer, BUFSIZE, "%b %d %H:%M:%S :", localtime(&tzgr));
+	}
+
 	va_start(az, fmt);
-	len = vsnprintf(buffer, BUFSIZE, fmt, az);
+	len += vsnprintf(buffer + len, BUFSIZE - len, fmt, az);
 	va_end(az);
 
 	if (len < 0 || len >= BUFSIZE) {
-		log_print(LOG_ERROR, "log_print: arguments too long");
 		errno = 0;
-		return;
+		return log_print(LOG_ERROR, "log_print: arguments too long");
 	}
 
 	if (errno) {
-		strncpy(buffer + len, ": ", BUFSIZE - len);
-		len += 2;
-		strncpy(buffer + len, strerror(errno), BUFSIZE - len);
+		len += snprintf(buffer + len, BUFSIZE - len, ": %s", strerror(errno));
+		errno = 0;
 	}
 
-	if (log_fd) {
-		char    tbuf[64];
-		time_t  tzgr;
-
-		time(&tzgr);
-		strftime(tbuf, sizeof(tbuf), "%b %d %H:%M:%S :", localtime(&tzgr));
-
-		fprintf(log_fd, "%s %s\n", tbuf, buffer);
-		fflush(log_fd);
-
-	} else {
-		fprintf(stderr, "%s\n", buffer);
-	}
-
-	errno = 0;
+	retval = fprintf((log_fd ? log_fd : stderr), "%s\n", buffer);
+	fflush(log_fd);
+	return retval;
 }
 
-static void log_close(void)
+void log_close(void)
 {
 	if (buffer)
 		free(buffer);
 
-	fclose(log_fd);
+	if (log_fd)
+		fclose(log_fd);
 }
 
-int log_init(char *logfile)
+int log_init(const char *logfile)
 {
+	if (log_fd != NULL)
+		log_close();
+
 	log_fd = fopen(logfile, "a");
 	if (log_fd == NULL) {
-		log_print(LOG_ERROR, "log_open('%s'): %s", logfile);
-		return 0;
+		fprintf(stderr, "log_init(): can not open logfile");
+		return -1;
 	}
-
-	if (atexit(log_close) != 0) {
-		log_print(LOG_ERROR, "log_open(): atexit()");
-		return 0;
-	}
-
-	log_print(LOG_EVERYTIME, "==========================");
-	return 1;
+	return 0;
+}
+
+void log_setprio(int prio)
+{
+	log_prio = prio;
 }
diff --git a/logging.h b/logging.h
index c6e32c0..82d028d 100644
--- a/logging.h
+++ b/logging.h
@@ -10,7 +10,10 @@
 
 #define LOG_EVERYTIME 0
 
-int log_init(char *logfile);
-void log_print(int prio, const char *fmt, ... );
+int log_init(const char *logfile);
+void log_close(void);
+void log_setprio(int prio);
+
+int log_print(int prio, const char *fmt, ... );
 
 #endif /* _LOGGING_H_ */