--- cvsnt-2.5.04.3236/./cvsapi/unix/SocketIO.cpp.org	2008-11-10 00:11:59.817179663 +0100
+++ cvsnt-2.5.04.3236/./cvsapi/unix/SocketIO.cpp	2008-11-10 00:13:32.297166956 +0100
@@ -182,6 +182,15 @@
 		sock = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
 		if( -1 == sock) {
 			CServerIo::trace(3,"Socket creation failed: %s",gai_strerror(errno));
+		} else {
+#ifdef IPV6_V6ONLY
+			/* Only communicate in IPv6 over AF_INET6 sockets. */
+			if (addr->ai_family == AF_INET6) {
+				int on = 1;
+				if (::setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) == -1)
+					CServerIo::trace(3, "setsockopt IPV6_V6ONLY: %s", strerror(errno));
+			}
+#endif
 		}
 		m_sockets.push_back(sock); // even push (-1) to keep order of m_sockets and m_pAddrInfo  
 	}