diff --git a/common/match.c b/common/match.c
index 2f154f06..706cbfe6 100644
--- a/common/match.c
+++ b/common/match.c
@@ -363,3 +363,63 @@ int	isvalidusername(char *username)
 	return 1;
 }
 
+/*
+ * Match an IP against a subnet (10.11.12.128/27, fdf0:584f:e66b::/48).
+ */
+int match_ipmask(char *mask, char *ip)
+{
+	int m, j;
+	u_long lmask;
+	char *p, dummy[128];
+	struct IN_ADDR mask_addr, ip_addr;
+
+	if (inetpton(AF_INET6, ip, (void *) ip_addr.s6_addr) != 1)
+		return -1;
+
+	strncpyzt(dummy, mask, sizeof(dummy));
+	mask = dummy;
+
+	if (!(p = index(mask, '/')))
+		return -1;
+
+	*p = '\0';
+
+	if (sscanf(p + 1, "%d", &m) != 1)
+		return -1;
+
+	if (!m)
+		return 0; /* x.x.x.x/0 always matches */
+
+	if (m < 0 || m > 128)
+		return -1;
+
+	if (inetpton(AF_INET6, mask, (void *) mask_addr.s6_addr) != 1)
+		return -1;
+
+	/* Make sure that the ipv4 notation still works. */
+	if (IN6_IS_ADDR_V4MAPPED(&mask_addr))
+	{
+		if (m <= 32)
+			m += 96;
+		if (m <= 96)
+			return -1;
+	}
+
+	j = m & 0x1F; /* number not multiple of 32 bits */
+	m >>= 5;      /* number of 32 bits */
+
+	if (m && memcmp((void *) (mask_addr.s6_addr),
+					(void *) (ip_addr.s6_addr), m << 2))
+		return 1;
+
+	if (j)
+	{
+		lmask = htonl((u_long) 0xffffffffL << (32 - j));
+		if ((((u_int32_t *) (mask_addr.s6_addr))[m] ^
+			 ((u_int32_t *) (ip_addr.s6_addr))[m]) &
+			lmask)
+			return 1;
+	}
+
+	return 0;
+}
\ No newline at end of file
diff --git a/common/match_ext.h b/common/match_ext.h
index 749ef87c..9b7ffeb7 100644
--- a/common/match_ext.h
+++ b/common/match_ext.h
@@ -41,4 +41,5 @@ EXTERN char *collapse (char *pattern);
 EXTERN int mycmp (char *s1, char *s2);
 EXTERN int myncmp (char *str1, char *str2, int n);
 EXTERN int isvalidusername (char *username);
+EXTERN int match_ipmask(char *mask, char *ip);
 #undef EXTERN
diff --git a/iauth/a_conf.c b/iauth/a_conf.c
index b916b34e..6290f2c3 100644
--- a/iauth/a_conf.c
+++ b/iauth/a_conf.c
@@ -45,67 +45,6 @@ static	void	conf_err(u_int nb, char *msg, char *chk)
 	exit(1);
 }
 
-/*
- * Match address by #IP bitmask (10.11.12.128/27)
- */
-static	int	match_ipmask(char *mask, char *ip)
-{
-	int m, j;
-	u_long lmask;
-	char *p, dummy[128];
-	struct IN_ADDR mask_addr, ip_addr;
-
-	if (inetpton(AF_INET6, ip, (void *) ip_addr.s6_addr) != 1)
-		return -1;
-
-	strncpyzt(dummy, mask, sizeof(dummy));
-	mask = dummy;
-
-	if (!(p = index(mask, '/')))
-		return -1;
-
-	*p = '\0';
-
-	if (sscanf(p + 1, "%d", &m) != 1)
-		return -1;
-
-	if (!m)
-		return 0; /* x.x.x.x/0 always matches */
-
-	if (m < 0 || m > 128)
-		return -1;
-
-	if (inetpton(AF_INET6, mask, (void *) mask_addr.s6_addr) != 1)
-		return -1;
-
-	/* Make sure that the ipv4 notation still works. */
-	if (IN6_IS_ADDR_V4MAPPED(&mask_addr))
-	{
-		if (m <= 32)
-			m += 96;
-		if (m <= 96)
-			return -1;
-	}
-
-	j = m & 0x1F; /* number not multiple of 32 bits */
-	m >>= 5;      /* number of 32 bits */
-
-	if (m && memcmp((void *) (mask_addr.s6_addr),
-					(void *) (ip_addr.s6_addr), m << 2))
-		return 1;
-
-	if (j)
-	{
-		lmask = htonl((u_long) 0xffffffffL << (32 - j));
-		if ((((u_int32_t *) (mask_addr.s6_addr))[m] ^
-			 ((u_int32_t *) (ip_addr.s6_addr))[m]) &
-			lmask)
-			return 1;
-	}
-
-	return 0;
-}
-
 /* conf_read: read the configuration file, instanciate modules */
 char	*conf_read(char *cfile)
 {
diff --git a/ircd/channel.c b/ircd/channel.c
index 2f2ab9c4..cbc96dde 100644
--- a/ircd/channel.c
+++ b/ircd/channel.c
@@ -389,7 +389,7 @@ static	Link	*match_modeid(int type, aClient *cptr, aChannel *chptr)
 				}
 				/* so now we check CIDR */
 				if (strchr(tmp->value.alist->host, '/') &&
-					match_ipmask(tmp->value.alist->host, cptr, 0) == 0)
+					match_ipmask_client(tmp->value.alist->host, cptr, 0) == 0)
 				{
 					break;
 				}
diff --git a/ircd/s_conf.c b/ircd/s_conf.c
index 22258a91..b037ec7b 100644
--- a/ircd/s_conf.c
+++ b/ircd/s_conf.c
@@ -450,7 +450,7 @@ void	det_confs_butmask(aClient *cptr, int mask)
  * Now should work for IPv6 too.
  * returns -1 on error, 0 on match, 1 when NO match.
  */
-int    match_ipmask(char *mask, aClient *cptr, int maskwithusername)
+int match_ipmask_client(char *mask, aClient *cptr, int maskwithusername)
 {
 	int	m;
 	char	*p;
@@ -623,9 +623,9 @@ int	attach_Iline(aClient *cptr, struct hostent *hp, char *sockhost)
 			if (strchr(aconf->host, '/'))	/* 1.2.3.0/24 */
 			{
 				
-				/* match_ipmask takes care of checking
+				/* match_ipmask_client takes care of checking
 				** possible username if aconf->host has '@' */
-				if (match_ipmask(aconf->host, cptr, 1))
+				if (match_ipmask_client(aconf->host, cptr, 1))
 				{
 					/* Try another I:line. */
 					continue;
@@ -1137,7 +1137,7 @@ aConfItem	*find_Oline(char *name, aClient *cptr)
 		*/
 		if (match(tmp->host, userhost) && match(tmp->host, userip) &&
 			(!strchr(tmp->host, '/') 
-			|| match_ipmask(tmp->host, cptr, 1)))
+			|| match_ipmask_client(tmp->host, cptr, 1)))
 			continue;
 		if (tmp->clients < MaxLinks(Class(tmp)))
 			return tmp;
@@ -2318,7 +2318,7 @@ int	find_kill(aClient *cptr, int timedklines, char **comment)
 		    {
 			if (strchr(tmp->host, '/'))
 			    {
-				if (match_ipmask((*tmp->host == '=') ?
+				if (match_ipmask_client((*tmp->host == '=') ?
 						 tmp->host+1: tmp->host, cptr, 1))
 					continue;
 			    }
@@ -2332,7 +2332,7 @@ int	find_kill(aClient *cptr, int timedklines, char **comment)
 		else /* resolved */
 			if (strchr(tmp->host, '/'))
 			    {
-				if (match_ipmask(tmp->host, cptr, 1))
+				if (match_ipmask_client(tmp->host, cptr, 1))
 					continue;
 			    }
 			else
@@ -2555,7 +2555,7 @@ void	find_bounce(aClient *cptr, int class, int fd)
 		{
 			if (strchr(aconf->host, '/'))
 			{
-				if (match_ipmask(aconf->host, cptr, 1))
+				if (match_ipmask_client(aconf->host, cptr, 1))
 					continue;
 			}
 			else if (match(aconf->host, cptr->sockhost))
@@ -2771,7 +2771,7 @@ void do_kline(int tkline, char *who, time_t time, char *user, char *host, char *
 			/* unresolved */
 			if (strchr(aconf->host, '/'))
 			{
-				if (match_ipmask(*aconf->host == '=' ?
+				if (match_ipmask_client(*aconf->host == '=' ?
 					aconf->host + 1 : aconf->host,
 					acptr, 1))
 				{
@@ -2798,7 +2798,7 @@ void do_kline(int tkline, char *who, time_t time, char *user, char *host, char *
 			}
 			if (strchr(aconf->host, '/'))
 			{
-				if (match_ipmask(aconf->host, acptr, 1))
+				if (match_ipmask_client(aconf->host, acptr, 1))
 				{
 					continue;
 				}
@@ -2903,7 +2903,7 @@ int	prep_kline(int tkline, aClient *cptr, aClient *sptr, int parc, char **parv)
 		/* disallow all forms of bad u@h format and block *@* without flags too */
 		err = 1;
 	}
-	if (!err && host && strchr(host, '/') && match_ipmask(host, sptr, 0) == -1)
+	if (!err && host && strchr(host, '/') && match_ipmask_client(host, sptr, 0) == -1)
 	{
 		/* check validity of 1.2.3.0/24 or it will be spewing errors
 		** for every connecting client. */
diff --git a/ircd/s_conf_ext.h b/ircd/s_conf_ext.h
index 0b8c3c6f..d96f5714 100644
--- a/ircd/s_conf_ext.h
+++ b/ircd/s_conf_ext.h
@@ -39,8 +39,7 @@ extern char *networkname;
 #define EXTERN
 #endif /* S_CONF_C */
 EXTERN void det_confs_butmask (aClient *cptr, int mask);
-EXTERN int match_ipmask (char *mask, aClient *cptr,
-	int maskwithusername);
+EXTERN int match_ipmask_client (char *mask, aClient *cptr, int maskwithusername);
 EXTERN int attach_Iline (aClient *cptr, Reg struct hostent *hp,
 			     char *sockhost);
 EXTERN aConfItem *count_cnlines (Reg Link *lp);
diff --git a/ircd/s_user.c b/ircd/s_user.c
index 5d7975d7..6e68955d 100644
--- a/ircd/s_user.c
+++ b/ircd/s_user.c
@@ -392,7 +392,7 @@ int	register_user(aClient *cptr, aClient *sptr, char *nick, char *username)
 				sptr->hostp->h_name : sptr->sockhost)) &&
 				match(xtmp->source_ip, sptr->user->sip) &&
 				strchr(xtmp->source_ip, '/') && 
-				match_ipmask(xtmp->source_ip, sptr, 0)))
+				match_ipmask_client(xtmp->source_ip, sptr, 0)))
 				continue;
 			SetXlined(sptr);
 			break;
diff --git a/support/Makefile.in b/support/Makefile.in
index 7c62849d..af976d12 100644
--- a/support/Makefile.in
+++ b/support/Makefile.in
@@ -154,7 +154,7 @@ IAUTH_OBJS = iauth.o a_conf.o a_io.o a_log.o \
              mod_pipe.o mod_rfc931.o mod_socks.o \
              mod_webproxy.o mod_dnsbl.o
 
-CHKCONF_COMMON_OBJS = match.o
+CHKCONF_COMMON_OBJS = match.o clsupport.o
 CHKCONF_OBJS = chkconf.o
 CHKCONF = chkconf