--- a/src/network/core/address.cpp
+++ b/src/network/core/address.cpp
@@ -89,6 +89,60 @@
 	return &this->address;
 }
 
+bool NetworkAddress::IsInNetmask(char *netmask)
+{
+	/* Resolve it if we didn't do it already */
+	if (!this->IsResolved()) this->GetAddress();
+
+	int cidr = this->address.ss_family == AF_INET ? 32 : 128;
+
+	NetworkAddress mask_address;
+
+	/* Check for CIDR separator */
+	char *chr_cidr = strchr(netmask, '/');
+	if (chr_cidr != NULL) {
+		int tmp_cidr = atoi(chr_cidr + 1);
+
+		/* Invalid CIDR, treat as single host */
+		if (tmp_cidr > 0 || tmp_cidr < cidr) cidr = tmp_cidr;
+
+		/* Remove and then replace the / so that NetworkAddress works on the IP portion */
+		*chr_cidr = '\0';
+		mask_address = NetworkAddress(netmask, 0, this->address.ss_family);
+		*chr_cidr = '/';
+	} else {
+		mask_address = NetworkAddress(netmask, 0, this->address.ss_family);
+	}
+
+	if (mask_address.GetAddressLength() == 0) return false;
+
+	uint32 *ip;
+	uint32 *mask;
+	switch (this->address.ss_family) {
+		case AF_INET:
+			ip = &((struct sockaddr_in*)&this->address)->sin_addr.s_addr;
+			mask = &((struct sockaddr_in*)&mask_address.address)->sin_addr.s_addr;
+			break;
+
+		case AF_INET6:
+			ip = ((struct sockaddr_in6*)&this->address)->sin6_addr.s6_addr32;
+			mask = ((struct sockaddr_in6*)&mask_address.address)->sin6_addr.s6_addr32;
+			break;
+
+		default:
+			NOT_REACHED();
+	}
+
+	while (cidr > 0) {
+		uint32 msk = cidr >= 32 ? -1 : htonl(-(1 << (32 - cidr)));
+		if ((*mask & msk) != (*ip & msk)) return false;
+
+		cidr -= 32;
+	}
+
+	return true;
+}
+
 SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, LoopProc func)
 {
 	struct addrinfo *ai;
@@ -104,7 +158,7 @@
 
 	int e = getaddrinfo(this->GetHostname(), port_name, &hints, &ai);
 	if (e != 0) {
-		DEBUG(net, 0, "getaddrinfo failed: %s", FS2OTTD(gai_strerror(e)));
+		DEBUG(net, 0, "getaddrinfo(%s, %s) failed: %s", this->GetHostname(), port_name, FS2OTTD(gai_strerror(e)));
 		return INVALID_SOCKET;
 	}
 

--- a/src/network/core/address.h
+++ b/src/network/core/address.h
@@ -159,6 +159,14 @@
 	}
 
 	/**
+	 * Checks whether this IP address is contained by the given netmask.
+	 * @param netmask the netmask in CIDR notation to test against.
+	 * @note netmask without /n assumes all bits need to match.
+	 * @return true if this IP is within the netmask.
+	 */
+	bool IsInNetmask(char *netmask);
+
+	/**
 	 * Compare the address of this class with the address of another.
 	 * @param address the other address.
 	 */

--- a/src/network/network.cpp
+++ b/src/network/network.cpp
@@ -470,7 +470,6 @@
 /* For the server, to accept new clients */
 static void NetworkAcceptClients()
 {
-	struct sockaddr_in sin;
 	NetworkClientSocket *cs;
 	bool banned;
 
@@ -478,6 +477,7 @@
 	assert(_listensocket != INVALID_SOCKET);
 
 	for (;;) {
+		struct sockaddr_storage sin;
 		memset(&sin, 0, sizeof(sin));
 		socklen_t sin_len = sizeof(sin);
 		SOCKET s = accept(_listensocket, (struct sockaddr*)&sin, &sin_len);
@@ -485,34 +485,15 @@
 
 		SetNonBlocking(s); // XXX error handling?
 
-		DEBUG(net, 1, "Client connected from %s on frame %d", inet_ntoa(sin.sin_addr), _frame_counter);
+		NetworkAddress address(sin, sin_len);
+		DEBUG(net, 1, "Client connected from %s on frame %d", address.GetHostname(), _frame_counter);
 
 		SetNoDelay(s); // XXX error handling?
 
 		/* Check if the client is banned */
 		banned = false;
 		for (char **iter = _network_ban_list.Begin(); iter != _network_ban_list.End(); iter++) {
-			/* Check for CIDR separator */
-			char *chr_cidr = strchr(*iter, '/');
-			if (chr_cidr != NULL) {
-				int cidr = atoi(chr_cidr + 1);
-
-				/* Invalid CIDR, treat as single host */
-				if (cidr <= 0 || cidr > 32) cidr = 32;
-
-				/* Remove and then replace the / so that inet_addr() works on the IP portion */
-				*chr_cidr = '\0';
-				uint32 ban_ip = inet_addr(*iter);
-				*chr_cidr = '/';
-
-				/* Convert CIDR to mask in network format */
-				uint32 mask = htonl(-(1 << (32 - cidr)));
-				if ((sin.sin_addr.s_addr & mask) == (ban_ip & mask)) banned = true;
-			} else {
-				/* No CIDR used, so just perform a simple IP test */
-				if (sin.sin_addr.s_addr == inet_addr(*iter)) banned = true;
-			}
-
+			banned = address.IsInNetmask(*iter);
 			if (banned) {
 				Packet p(PACKET_SERVER_BANNED);
 				p.PrepareToSend();
@@ -545,7 +526,7 @@
 		 *  the client stays inactive */
 		cs->status = STATUS_INACTIVE;
 
-		cs->GetInfo()->client_ip = sin.sin_addr.s_addr; // Save the IP of the client
+		cs->GetInfo()->client_ip = ((sockaddr_in*)&sin)->sin_addr.s_addr; // Save the IP of the client
 	}
 }