2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 1996, Nickolay Dudorov
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice unmodified, this list of conditions, and the following
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * 'nos-tun' program configure tunN interface as a point-to-point
33 * connection with two "pseudo"-addresses between this host and
36 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP)
37 * (known as NOS-incapsulation in CISCO-routers' terminology).
39 * 'nos-tun' can works with itself and CISCO-routers.
40 * (It may also work with Linux 'nos-tun's, but
41 * I have no Linux system here to test with).
43 * BUGS (or features ?):
44 * - you must specify ONE of the target host's addresses
45 * ( nos-tun sends and accepts packets only to/from this
47 * - there can be only ONE tunnel between two hosts,
48 * more precisely - between given host and (one of)
49 * target hosts' address(es)
50 * (and why do you want more ?)
54 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com>
55 * I added a new flag for ip protocol number.
56 * We are using 4 as protocol number in ampr.org.
61 static const char rcsid[] =
65 #include <sys/types.h>
66 #include <sys/ioctl.h>
67 #include <sys/signal.h>
68 #include <sys/socket.h>
71 #include <netinet/in.h>
72 #include <netinet/in_systm.h>
73 #include <netinet/ip.h>
75 #include <arpa/inet.h>
84 /* Tunnel interface configuration stuff */
85 static struct ifaliasreq ifra;
86 static struct ifreq ifrq;
88 /* Global descriptors */
89 int net; /* socket descriptor */
90 int tun; /* tunnel descriptor */
92 static void usage(void);
95 Set_address(char *addr, struct sockaddr_in *sin)
99 bzero((char *)sin, sizeof(struct sockaddr));
100 sin->sin_family = AF_INET;
101 if((sin->sin_addr.s_addr = inet_addr(addr)) == INADDR_NONE) {
102 hp = gethostbyname(addr);
104 syslog(LOG_ERR,"unknown host %s", addr);
107 sin->sin_family = hp->h_addrtype;
108 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
114 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr)
117 struct sockaddr_in *sin;
119 /* Open tun device */
120 tun = open(dev_name, O_RDWR);
122 syslog(LOG_ERR,"can't open %s - %m", dev_name);
127 * At first, name the interface.
129 bzero((char *)&ifra, sizeof(ifra));
130 bzero((char *)&ifrq, sizeof(ifrq));
132 strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ);
133 strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ);
135 s = socket(AF_INET, SOCK_DGRAM, 0);
137 syslog(LOG_ERR,"can't open socket - %m");
142 * Delete (previous) addresses for interface
145 * On FreeBSD this ioctl returns error
146 * when tunN have no addresses, so - log and ignore it.
149 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
150 syslog(LOG_ERR,"SIOCDIFADDR - %m");
154 * Set interface address
156 sin = (struct sockaddr_in *)&(ifra.ifra_addr);
157 bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
158 sin->sin_len = sizeof(*sin);
161 * Set destination address
163 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
164 if(Set_address(theiraddr,sin)) {
165 syslog(LOG_ERR,"bad destination address: %s",theiraddr);
168 sin->sin_len = sizeof(*sin);
170 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
171 syslog(LOG_ERR,"can't set interface address - %m");
176 * Now, bring up the interface.
178 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
179 syslog(LOG_ERR,"can't get interface flags - %m");
183 ifrq.ifr_flags |= IFF_UP;
184 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
188 syslog(LOG_ERR,"can't set interface UP - %m");
201 syslog(LOG_INFO,"exiting");
205 s = socket(AF_INET, SOCK_DGRAM, 0);
207 syslog(LOG_ERR,"can't open socket - %m");
212 * Shut down interface.
214 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
215 syslog(LOG_ERR,"can't get interface flags - %m");
219 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
220 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
221 syslog(LOG_ERR,"can't set interface DOWN - %m");
226 * Delete addresses for interface
228 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
229 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
230 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
231 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
232 syslog(LOG_ERR,"can't delete interface's addresses - %m");
242 int main (int argc, char **argv)
246 char *dev_name = NULL;
247 char *point_to = NULL;
248 char *to_point = NULL;
251 char *protocol = NULL;
254 struct sockaddr t_laddr; /* Source address of tunnel */
255 struct sockaddr whereto; /* Destination of tunnel */
256 struct sockaddr wherefrom; /* Source of tunnel */
257 struct sockaddr_in *to;
259 char buf[0x2000]; /* Packets buffer */
260 struct ip *ip = (struct ip *)buf;
262 fd_set rfds; /* File descriptors for select() */
263 int nfds; /* Return from select() */
264 int lastfd; /* highest fd we care about */
267 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
286 if ((argc != 1 && argc != 2) || (dev_name == NULL) ||
287 (point_to == NULL) || (to_point == NULL)) {
294 protnum = atoi(protocol);
299 source = *argv++; target = *argv;
302 /* Establish logging through 'syslog' */
303 openlog("nos-tun", LOG_PID, LOG_DAEMON);
305 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
310 if(tun_open(dev_name, &t_laddr, to_point)) {
315 to = (struct sockaddr_in *)&whereto;
316 if(Set_address(target, to))
319 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
320 syslog(LOG_ERR,"can't open socket - %m");
325 if (Set_address(source, (struct sockaddr_in *)&wherefrom))
327 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
328 syslog(LOG_ERR, "can't bind source address - %m");
333 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
334 syslog(LOG_ERR,"can't connect to target - %m");
342 /* Install signal handlers */
343 (void)signal(SIGHUP,Finish);
344 (void)signal(SIGINT,Finish);
345 (void)signal(SIGTERM,Finish);
353 /* Set file descriptors for select() */
355 FD_SET(tun,&rfds); FD_SET(net,&rfds);
357 nfds = select(lastfd+1,&rfds,NULL,NULL,NULL);
359 syslog(LOG_ERR,"interrupted select");
363 if(nfds == 0) { /* Impossible ? */
364 syslog(LOG_ERR,"timeout in select");
370 if(FD_ISSET(net,&rfds)) {
371 /* Read from socket ... */
372 len = read(net, buf, sizeof(buf));
373 /* Check if this is "our" packet */
374 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
375 /* ... skip encapsulation headers ... */
376 ipoff = (ip->ip_hl << 2);
377 /* ... and write to tun-device */
378 write(tun,buf+ipoff,len-ipoff);
382 if(FD_ISSET(tun,&rfds)) {
383 /* Read from tun ... */
384 len = read(tun, buf, sizeof(buf));
385 /* ... and send to network */
386 if(send(net, buf, len,0) <= 0) {
387 syslog(LOG_ERR,"can't send - %m");
397 "usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n");