Get the client libraries to correctly attempt password changes when using IPv6,
tweaked to apply to older releases.  Original patch by Sumit Bose, RT#6661

Index: src/lib/krb5/os/changepw.c
===================================================================
--- src/lib/krb5/os/changepw.c	(revision 23766)
+++ src/lib/krb5/os/changepw.c	(revision 23767)
@@ -65,20 +65,23 @@
     int sockType = (useTcp ? SOCK_STREAM : SOCK_DGRAM);
 
     code = krb5int_locate_server (context, realm, addrlist,
-				  locate_service_kpasswd, sockType, AF_INET);
+				  locate_service_kpasswd, sockType, AF_UNSPEC);
 
     if (code == KRB5_REALM_CANT_RESOLVE || code == KRB5_REALM_UNKNOWN) {
 	code = krb5int_locate_server (context, realm, addrlist,
 				      locate_service_kadmin, SOCK_STREAM,
-				      AF_INET);
+				      AF_UNSPEC);
 	if (!code) {
 	    /* Success with admin_server but now we need to change the
 	       port number to use DEFAULT_KPASSWD_PORT and the socktype.  */
 	    int i;
 	    for (i=0; i<addrlist->naddrs; i++) {
 		struct addrinfo *a = addrlist->addrs[i].ai;
+		krb5_ui_2 kpasswd_port = htons(DEFAULT_KPASSWD_PORT);
 		if (a->ai_family == AF_INET)
-		    sa2sin (a->ai_addr)->sin_port = htons(DEFAULT_KPASSWD_PORT);
+		    sa2sin (a->ai_addr)->sin_port = kpasswd_port;
+		if (a->ai_family == AF_INET6)
+		    sa2sin6 (a->ai_addr)->sin6_port = kpasswd_port;
 		if (sockType != SOCK_STREAM)
 		    a->ai_socktype = sockType;
 	    }
@@ -131,10 +134,16 @@
     /* some brain-dead OS's don't return useful information from
      * the getsockname call.  Namely, windows and solaris.  */
 
-    if (ss2sin(&local_addr)->sin_addr.s_addr != 0) {
+    if (local_addr.ss_family == AF_INET &&
+	ss2sin(&local_addr)->sin_addr.s_addr != 0) {
 	local_kaddr.addrtype = ADDRTYPE_INET;
 	local_kaddr.length = sizeof(ss2sin(&local_addr)->sin_addr);
 	local_kaddr.contents = (krb5_octet *) &ss2sin(&local_addr)->sin_addr;
+    } else if (local_addr.ss_family == AF_INET6 &&
+	ss2sin6(&local_addr)->sin6_addr.s6_addr != 0) {
+	local_kaddr.addrtype = ADDRTYPE_INET6;
+	local_kaddr.length = sizeof(ss2sin6(&local_addr)->sin6_addr);
+	local_kaddr.contents = (krb5_octet *) &ss2sin6(&local_addr)->sin6_addr;
     } else {
 	krb5_address **addrs;
 
@@ -278,9 +287,19 @@
 	    break;
 	}
 
-	remote_kaddr.addrtype = ADDRTYPE_INET;
-	remote_kaddr.length = sizeof(ss2sin(&remote_addr)->sin_addr);
-	remote_kaddr.contents = (krb5_octet *) &ss2sin(&remote_addr)->sin_addr;
+	if (remote_addr.ss_family == AF_INET) {
+	    remote_kaddr.addrtype = ADDRTYPE_INET;
+	    remote_kaddr.length = sizeof(ss2sin(&remote_addr)->sin_addr);
+	    remote_kaddr.contents =
+		(krb5_octet *) &ss2sin(&remote_addr)->sin_addr;
+	} else if (remote_addr.ss_family == AF_INET6) {
+	    remote_kaddr.addrtype = ADDRTYPE_INET6;
+	    remote_kaddr.length = sizeof(ss2sin6(&remote_addr)->sin6_addr);
+	    remote_kaddr.contents =
+		(krb5_octet *) &ss2sin6(&remote_addr)->sin6_addr;
+	} else {
+	    break;
+	}
 
 	if ((code = krb5_auth_con_setaddrs(callback_ctx.context,  
 					   callback_ctx.auth_context,