forge.net/>  and explains these in detail, as well as
   some other issues.
 
+  There is also a related point-to-point only "ucast" transport.
+  This is useful when your network does not support multicast, and
+  all network connections are simple point to point links.
+
+  The full set of command line options for this transport are
+
+
+       ethn=ucast,ethernet address,remote address,listen port,remote port
+
+
 
 
   6\b6.\b.6\b6.\b.  T\bTU\bUN\bN/\b/T\bTA\bAP\bP w\bwi\bit\bth\bh t\bth\bhe\be u\bum\bml\bl_\b_n\bne\bet\bt h\bhe\bel\blp\bpe\ber\br
 
 slip-objs := slip_kern.o slip_user.o
 slirp-objs := slirp_kern.o slirp_user.o
 daemon-objs := daemon_kern.o daemon_user.o
-mcast-objs := mcast_kern.o mcast_user.o
+umcast-objs := umcast_kern.o umcast_user.o
 net-objs := net_kern.o net_user.o
 mconsole-objs := mconsole_kern.o mconsole_user.o
 hostaudio-objs := hostaudio_kern.o
 obj-$(CONFIG_UML_NET_SLIRP) += slirp.o slip_common.o
 obj-$(CONFIG_UML_NET_DAEMON) += daemon.o 
 obj-$(CONFIG_UML_NET_VDE) += vde.o
-obj-$(CONFIG_UML_NET_MCAST) += mcast.o 
+obj-$(CONFIG_UML_NET_MCAST) += umcast.o
 obj-$(CONFIG_UML_NET_PCAP) += pcap.o
 obj-$(CONFIG_UML_NET) += net.o 
 obj-$(CONFIG_MCONSOLE) += mconsole.o
 
+++ /dev/null
-/* 
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
- */
-
-#ifndef __DRIVERS_MCAST_H
-#define __DRIVERS_MCAST_H
-
-#include "net_user.h"
-
-struct mcast_data {
-       char *addr;
-       unsigned short port;
-       void *mcast_addr;
-       int ttl;
-       void *dev;
-};
-
-extern const struct net_user_info mcast_user_info;
-
-extern int mcast_user_write(int fd, void *buf, int len, 
-                           struct mcast_data *pri);
-
-#endif
 
+++ /dev/null
-/*
- * user-mode-linux networking multicast transport
- * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- *
- * based on the existing uml-networking code, which is
- * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
- * James Leu (jleu@mindspring.net).
- * Copyright (C) 2001 by various other people who didn't put their name here.
- *
- * Licensed under the GPL.
- */
-
-#include "linux/init.h"
-#include <linux/netdevice.h>
-#include "mcast.h"
-#include "net_kern.h"
-
-struct mcast_init {
-       char *addr;
-       int port;
-       int ttl;
-};
-
-static void mcast_init(struct net_device *dev, void *data)
-{
-       struct uml_net_private *pri;
-       struct mcast_data *dpri;
-       struct mcast_init *init = data;
-
-       pri = netdev_priv(dev);
-       dpri = (struct mcast_data *) pri->user;
-       dpri->addr = init->addr;
-       dpri->port = init->port;
-       dpri->ttl = init->ttl;
-       dpri->dev = dev;
-
-       printk("mcast backend multicast address: %s:%u, TTL:%u\n",
-              dpri->addr, dpri->port, dpri->ttl);
-}
-
-static int mcast_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
-{
-       return net_recvfrom(fd, skb_mac_header(skb),
-                           skb->dev->mtu + ETH_HEADER_OTHER);
-}
-
-static int mcast_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
-{
-       return mcast_user_write(fd, skb->data, skb->len,
-                               (struct mcast_data *) &lp->user);
-}
-
-static const struct net_kern_info mcast_kern_info = {
-       .init                   = mcast_init,
-       .protocol               = eth_protocol,
-       .read                   = mcast_read,
-       .write                  = mcast_write,
-};
-
-static int mcast_setup(char *str, char **mac_out, void *data)
-{
-       struct mcast_init *init = data;
-       char *port_str = NULL, *ttl_str = NULL, *remain;
-       char *last;
-
-       *init = ((struct mcast_init)
-               { .addr         = "239.192.168.1",
-                 .port         = 1102,
-                 .ttl          = 1 });
-
-       remain = split_if_spec(str, mac_out, &init->addr, &port_str, &ttl_str,
-                              NULL);
-       if (remain != NULL) {
-               printk(KERN_ERR "mcast_setup - Extra garbage on "
-                      "specification : '%s'\n", remain);
-               return 0;
-       }
-
-       if (port_str != NULL) {
-               init->port = simple_strtoul(port_str, &last, 10);
-               if ((*last != '\0') || (last == port_str)) {
-                       printk(KERN_ERR "mcast_setup - Bad port : '%s'\n",
-                              port_str);
-                       return 0;
-               }
-       }
-
-       if (ttl_str != NULL) {
-               init->ttl = simple_strtoul(ttl_str, &last, 10);
-               if ((*last != '\0') || (last == ttl_str)) {
-                       printk(KERN_ERR "mcast_setup - Bad ttl : '%s'\n",
-                              ttl_str);
-                       return 0;
-               }
-       }
-
-       printk(KERN_INFO "Configured mcast device: %s:%u-%u\n", init->addr,
-              init->port, init->ttl);
-
-       return 1;
-}
-
-static struct transport mcast_transport = {
-       .list           = LIST_HEAD_INIT(mcast_transport.list),
-       .name           = "mcast",
-       .setup          = mcast_setup,
-       .user           = &mcast_user_info,
-       .kern           = &mcast_kern_info,
-       .private_size   = sizeof(struct mcast_data),
-       .setup_size     = sizeof(struct mcast_init),
-};
-
-static int register_mcast(void)
-{
-       register_transport(&mcast_transport);
-       return 0;
-}
-
-late_initcall(register_mcast);
 
+++ /dev/null
-/*
- * user-mode-linux networking multicast transport
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
- *
- * based on the existing uml-networking code, which is
- * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
- * James Leu (jleu@mindspring.net).
- * Copyright (C) 2001 by various other people who didn't put their name here.
- *
- * Licensed under the GPL.
- *
- */
-
-#include <unistd.h>
-#include <errno.h>
-#include <netinet/in.h>
-#include "kern_constants.h"
-#include "mcast.h"
-#include "net_user.h"
-#include "um_malloc.h"
-#include "user.h"
-
-static struct sockaddr_in *new_addr(char *addr, unsigned short port)
-{
-       struct sockaddr_in *sin;
-
-       sin = uml_kmalloc(sizeof(struct sockaddr_in), UM_GFP_KERNEL);
-       if (sin == NULL) {
-               printk(UM_KERN_ERR "new_addr: allocation of sockaddr_in "
-                      "failed\n");
-               return NULL;
-       }
-       sin->sin_family = AF_INET;
-       sin->sin_addr.s_addr = in_aton(addr);
-       sin->sin_port = htons(port);
-       return sin;
-}
-
-static int mcast_user_init(void *data, void *dev)
-{
-       struct mcast_data *pri = data;
-
-       pri->mcast_addr = new_addr(pri->addr, pri->port);
-       pri->dev = dev;
-       return 0;
-}
-
-static void mcast_remove(void *data)
-{
-       struct mcast_data *pri = data;
-
-       kfree(pri->mcast_addr);
-       pri->mcast_addr = NULL;
-}
-
-static int mcast_open(void *data)
-{
-       struct mcast_data *pri = data;
-       struct sockaddr_in *sin = pri->mcast_addr;
-       struct ip_mreq mreq;
-       int fd, yes = 1, err = -EINVAL;
-
-
-       if ((sin->sin_addr.s_addr == 0) || (sin->sin_port == 0))
-               goto out;
-
-       fd = socket(AF_INET, SOCK_DGRAM, 0);
-
-       if (fd < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open : data socket failed, "
-                      "errno = %d\n", errno);
-               goto out;
-       }
-
-       if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open: SO_REUSEADDR failed, "
-                      "errno = %d\n", errno);
-               goto out_close;
-       }
-
-       /* set ttl according to config */
-       if (setsockopt(fd, SOL_IP, IP_MULTICAST_TTL, &pri->ttl,
-                      sizeof(pri->ttl)) < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_TTL failed, "
-                      "error = %d\n", errno);
-               goto out_close;
-       }
-
-       /* set LOOP, so data does get fed back to local sockets */
-       if (setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP, &yes, sizeof(yes)) < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open: IP_MULTICAST_LOOP failed, "
-                      "error = %d\n", errno);
-               goto out_close;
-       }
-
-       /* bind socket to mcast address */
-       if (bind(fd, (struct sockaddr *) sin, sizeof(*sin)) < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open : data bind failed, "
-                      "errno = %d\n", errno);
-               goto out_close;
-       }
-
-       /* subscribe to the multicast group */
-       mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
-       mreq.imr_interface.s_addr = 0;
-       if (setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP,
-                      &mreq, sizeof(mreq)) < 0) {
-               err = -errno;
-               printk(UM_KERN_ERR "mcast_open: IP_ADD_MEMBERSHIP failed, "
-                      "error = %d\n", errno);
-               printk(UM_KERN_ERR "There appears not to be a multicast-"
-                      "capable network interface on the host.\n");
-               printk(UM_KERN_ERR "eth0 should be configured in order to use "
-                      "the multicast transport.\n");
-               goto out_close;
-       }
-
-       return fd;
-
- out_close:
-       close(fd);
- out:
-       return err;
-}
-
-static void mcast_close(int fd, void *data)
-{
-       struct ip_mreq mreq;
-       struct mcast_data *pri = data;
-       struct sockaddr_in *sin = pri->mcast_addr;
-
-       mreq.imr_multiaddr.s_addr = sin->sin_addr.s_addr;
-       mreq.imr_interface.s_addr = 0;
-       if (setsockopt(fd, SOL_IP, IP_DROP_MEMBERSHIP,
-                      &mreq, sizeof(mreq)) < 0) {
-               printk(UM_KERN_ERR "mcast_open: IP_DROP_MEMBERSHIP failed, "
-                      "error = %d\n", errno);
-       }
-
-       close(fd);
-}
-
-int mcast_user_write(int fd, void *buf, int len, struct mcast_data *pri)
-{
-       struct sockaddr_in *data_addr = pri->mcast_addr;
-
-       return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
-}
-
-const struct net_user_info mcast_user_info = {
-       .init           = mcast_user_init,
-       .open           = mcast_open,
-       .close          = mcast_close,
-       .remove         = mcast_remove,
-       .add_address    = NULL,
-       .delete_address = NULL,
-       .mtu            = ETH_MAX_PACKET,
-       .max_packet     = ETH_MAX_PACKET + ETH_HEADER_OTHER,
-};
 
--- /dev/null
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __DRIVERS_UMCAST_H
+#define __DRIVERS_UMCAST_H
+
+#include "net_user.h"
+
+struct umcast_data {
+       char *addr;
+       unsigned short lport;
+       unsigned short rport;
+       void *listen_addr;
+       void *remote_addr;
+       int ttl;
+       int unicast;
+       void *dev;
+};
+
+extern const struct net_user_info umcast_user_info;
+
+extern int umcast_user_write(int fd, void *buf, int len,
+                            struct umcast_data *pri);
+
+#endif
 
--- /dev/null
+/*
+ * user-mode-linux networking multicast transport
+ * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ *
+ * based on the existing uml-networking code, which is
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
+ * James Leu (jleu@mindspring.net).
+ * Copyright (C) 2001 by various other people who didn't put their name here.
+ *
+ * Licensed under the GPL.
+ */
+
+#include "linux/init.h"
+#include <linux/netdevice.h>
+#include "umcast.h"
+#include "net_kern.h"
+
+struct umcast_init {
+       char *addr;
+       int lport;
+       int rport;
+       int ttl;
+       bool unicast;
+};
+
+static void umcast_init(struct net_device *dev, void *data)
+{
+       struct uml_net_private *pri;
+       struct umcast_data *dpri;
+       struct umcast_init *init = data;
+
+       pri = netdev_priv(dev);
+       dpri = (struct umcast_data *) pri->user;
+       dpri->addr = init->addr;
+       dpri->lport = init->lport;
+       dpri->rport = init->rport;
+       dpri->unicast = init->unicast;
+       dpri->ttl = init->ttl;
+       dpri->dev = dev;
+
+       if (dpri->unicast) {
+               printk(KERN_INFO "ucast backend address: %s:%u listen port: "
+                      "%u\n", dpri->addr, dpri->rport, dpri->lport);
+       } else {
+               printk(KERN_INFO "mcast backend multicast address: %s:%u, "
+                      "TTL:%u\n", dpri->addr, dpri->lport, dpri->ttl);
+       }
+}
+
+static int umcast_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+       return net_recvfrom(fd, skb_mac_header(skb),
+                           skb->dev->mtu + ETH_HEADER_OTHER);
+}
+
+static int umcast_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+       return umcast_user_write(fd, skb->data, skb->len,
+                               (struct umcast_data *) &lp->user);
+}
+
+static const struct net_kern_info umcast_kern_info = {
+       .init                   = umcast_init,
+       .protocol               = eth_protocol,
+       .read                   = umcast_read,
+       .write                  = umcast_write,
+};
+
+static int mcast_setup(char *str, char **mac_out, void *data)
+{
+       struct umcast_init *init = data;
+       char *port_str = NULL, *ttl_str = NULL, *remain;
+       char *last;
+
+       *init = ((struct umcast_init)
+               { .addr = "239.192.168.1",
+                 .lport        = 1102,
+                 .ttl  = 1 });
+
+       remain = split_if_spec(str, mac_out, &init->addr, &port_str, &ttl_str,
+                              NULL);
+       if (remain != NULL) {
+               printk(KERN_ERR "mcast_setup - Extra garbage on "
+                      "specification : '%s'\n", remain);
+               return 0;
+       }
+
+       if (port_str != NULL) {
+               init->lport = simple_strtoul(port_str, &last, 10);
+               if ((*last != '\0') || (last == port_str)) {
+                       printk(KERN_ERR "mcast_setup - Bad port : '%s'\n",
+                              port_str);
+                       return 0;
+               }
+       }
+
+       if (ttl_str != NULL) {
+               init->ttl = simple_strtoul(ttl_str, &last, 10);
+               if ((*last != '\0') || (last == ttl_str)) {
+                       printk(KERN_ERR "mcast_setup - Bad ttl : '%s'\n",
+                              ttl_str);
+                       return 0;
+               }
+       }
+
+       init->unicast = false;
+       init->rport = init->lport;
+
+       printk(KERN_INFO "Configured mcast device: %s:%u-%u\n", init->addr,
+              init->lport, init->ttl);
+
+       return 1;
+}
+
+static int ucast_setup(char *str, char **mac_out, void *data)
+{
+       struct umcast_init *init = data;
+       char *lport_str = NULL, *rport_str = NULL, *remain;
+       char *last;
+
+       *init = ((struct umcast_init)
+               { .addr         = "",
+                 .lport        = 1102,
+                 .rport        = 1102 });
+
+       remain = split_if_spec(str, mac_out, &init->addr,
+                              &lport_str, &rport_str, NULL);
+       if (remain != NULL) {
+               printk(KERN_ERR "ucast_setup - Extra garbage on "
+                      "specification : '%s'\n", remain);
+               return 0;
+       }
+
+       if (lport_str != NULL) {
+               init->lport = simple_strtoul(lport_str, &last, 10);
+               if ((*last != '\0') || (last == lport_str)) {
+                       printk(KERN_ERR "ucast_setup - Bad listen port : "
+                              "'%s'\n", lport_str);
+                       return 0;
+               }
+       }
+
+       if (rport_str != NULL) {
+               init->rport = simple_strtoul(rport_str, &last, 10);
+               if ((*last != '\0') || (last == rport_str)) {
+                       printk(KERN_ERR "ucast_setup - Bad remote port : "
+                              "'%s'\n", rport_str);
+                       return 0;
+               }
+       }
+
+       init->unicast = true;
+
+       printk(KERN_INFO "Configured ucast device: :%u -> %s:%u\n",
+              init->lport, init->addr, init->rport);
+
+       return 1;
+}
+
+static struct transport mcast_transport = {
+       .list   = LIST_HEAD_INIT(mcast_transport.list),
+       .name   = "mcast",
+       .setup  = mcast_setup,
+       .user   = &umcast_user_info,
+       .kern   = &umcast_kern_info,
+       .private_size   = sizeof(struct umcast_data),
+       .setup_size     = sizeof(struct umcast_init),
+};
+
+static struct transport ucast_transport = {
+       .list   = LIST_HEAD_INIT(ucast_transport.list),
+       .name   = "ucast",
+       .setup  = ucast_setup,
+       .user   = &umcast_user_info,
+       .kern   = &umcast_kern_info,
+       .private_size   = sizeof(struct umcast_data),
+       .setup_size     = sizeof(struct umcast_init),
+};
+
+static int register_umcast(void)
+{
+       register_transport(&mcast_transport);
+       register_transport(&ucast_transport);
+       return 0;
+}
+
+late_initcall(register_umcast);
 
--- /dev/null
+/*
+ * user-mode-linux networking multicast transport
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
+ *
+ * based on the existing uml-networking code, which is
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
+ * James Leu (jleu@mindspring.net).
+ * Copyright (C) 2001 by various other people who didn't put their name here.
+ *
+ * Licensed under the GPL.
+ *
+ */
+
+#include <unistd.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include "kern_constants.h"
+#include "umcast.h"
+#include "net_user.h"
+#include "um_malloc.h"
+#include "user.h"
+
+static struct sockaddr_in *new_addr(char *addr, unsigned short port)
+{
+       struct sockaddr_in *sin;
+
+       sin = uml_kmalloc(sizeof(struct sockaddr_in), UM_GFP_KERNEL);
+       if (sin == NULL) {
+               printk(UM_KERN_ERR "new_addr: allocation of sockaddr_in "
+                      "failed\n");
+               return NULL;
+       }
+       sin->sin_family = AF_INET;
+       if (addr)
+               sin->sin_addr.s_addr = in_aton(addr);
+       else
+               sin->sin_addr.s_addr = INADDR_ANY;
+       sin->sin_port = htons(port);
+       return sin;
+}
+
+static int umcast_user_init(void *data, void *dev)
+{
+       struct umcast_data *pri = data;
+
+       pri->remote_addr = new_addr(pri->addr, pri->rport);
+       if (pri->unicast)
+               pri->listen_addr = new_addr(NULL, pri->lport);
+       else
+               pri->listen_addr = pri->remote_addr;
+       pri->dev = dev;
+       return 0;
+}
+
+static void umcast_remove(void *data)
+{
+       struct umcast_data *pri = data;
+
+       kfree(pri->listen_addr);
+       if (pri->unicast)
+               kfree(pri->remote_addr);
+       pri->listen_addr = pri->remote_addr = NULL;
+}
+
+static int umcast_open(void *data)
+{
+       struct umcast_data *pri = data;
+       struct sockaddr_in *lsin = pri->listen_addr;
+       struct sockaddr_in *rsin = pri->remote_addr;
+       struct ip_mreq mreq;
+       int fd, yes = 1, err = -EINVAL;
+
+
+       if ((!pri->unicast && lsin->sin_addr.s_addr == 0) ||
+           (rsin->sin_addr.s_addr == 0) ||
+           (lsin->sin_port == 0) || (rsin->sin_port == 0))
+               goto out;
+
+       fd = socket(AF_INET, SOCK_DGRAM, 0);
+
+       if (fd < 0) {
+               err = -errno;
+               printk(UM_KERN_ERR "umcast_open : data socket failed, "
+                      "errno = %d\n", errno);
+               goto out;
+       }
+
+       if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
+               err = -errno;
+               printk(UM_KERN_ERR "umcast_open: SO_REUSEADDR failed, "
+                      "errno = %d\n", errno);
+               goto out_close;
+       }
+
+       if (!pri->unicast) {
+               /* set ttl according to config */
+               if (setsockopt(fd, SOL_IP, IP_MULTICAST_TTL, &pri->ttl,
+                              sizeof(pri->ttl)) < 0) {
+                       err = -errno;
+                       printk(UM_KERN_ERR "umcast_open: IP_MULTICAST_TTL "
+                              "failed, error = %d\n", errno);
+                       goto out_close;
+               }
+
+               /* set LOOP, so data does get fed back to local sockets */
+               if (setsockopt(fd, SOL_IP, IP_MULTICAST_LOOP,
+                              &yes, sizeof(yes)) < 0) {
+                       err = -errno;
+                       printk(UM_KERN_ERR "umcast_open: IP_MULTICAST_LOOP "
+                              "failed, error = %d\n", errno);
+                       goto out_close;
+               }
+       }
+
+       /* bind socket to the address */
+       if (bind(fd, (struct sockaddr *) lsin, sizeof(*lsin)) < 0) {
+               err = -errno;
+               printk(UM_KERN_ERR "umcast_open : data bind failed, "
+                      "errno = %d\n", errno);
+               goto out_close;
+       }
+
+       if (!pri->unicast) {
+               /* subscribe to the multicast group */
+               mreq.imr_multiaddr.s_addr = lsin->sin_addr.s_addr;
+               mreq.imr_interface.s_addr = 0;
+               if (setsockopt(fd, SOL_IP, IP_ADD_MEMBERSHIP,
+                              &mreq, sizeof(mreq)) < 0) {
+                       err = -errno;
+                       printk(UM_KERN_ERR "umcast_open: IP_ADD_MEMBERSHIP "
+                              "failed, error = %d\n", errno);
+                       printk(UM_KERN_ERR "There appears not to be a "
+                              "multicast-capable network interface on the "
+                              "host.\n");
+                       printk(UM_KERN_ERR "eth0 should be configured in order "
+                              "to use the multicast transport.\n");
+                       goto out_close;
+               }
+       }
+
+       return fd;
+
+ out_close:
+       close(fd);
+ out:
+       return err;
+}
+
+static void umcast_close(int fd, void *data)
+{
+       struct umcast_data *pri = data;
+
+       if (!pri->unicast) {
+               struct ip_mreq mreq;
+               struct sockaddr_in *lsin = pri->listen_addr;
+
+               mreq.imr_multiaddr.s_addr = lsin->sin_addr.s_addr;
+               mreq.imr_interface.s_addr = 0;
+               if (setsockopt(fd, SOL_IP, IP_DROP_MEMBERSHIP,
+                              &mreq, sizeof(mreq)) < 0) {
+                       printk(UM_KERN_ERR "umcast_close: IP_DROP_MEMBERSHIP "
+                              "failed, error = %d\n", errno);
+               }
+       }
+
+       close(fd);
+}
+
+int umcast_user_write(int fd, void *buf, int len, struct umcast_data *pri)
+{
+       struct sockaddr_in *data_addr = pri->remote_addr;
+
+       return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
+}
+
+const struct net_user_info umcast_user_info = {
+       .init   = umcast_user_init,
+       .open   = umcast_open,
+       .close  = umcast_close,
+       .remove = umcast_remove,
+       .add_address    = NULL,
+       .delete_address = NULL,
+       .mtu    = ETH_MAX_PACKET,
+       .max_packet     = ETH_MAX_PACKET + ETH_HEADER_OTHER,
+};