2 * Copyright (c) 1996, Nickolay Dudorov
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * 'nos-tun' program configure tunN interface as a point-to-point
31 * connection with two "pseudo"-addresses between this host and
34 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP)
35 * (known as NOS-incapsulation in CISCO-routers' terminology).
37 * 'nos-tun' can works with itself and CISCO-routers.
38 * (It may also work with Linux 'nos-tun's, but
39 * I have no Linux system here to test with).
41 * BUGS (or features ?):
42 * - you must specify ONE of the target host's addresses
43 * ( nos-tun sends and accepts packets only to/from this
45 * - there can be only ONE tunnel between two hosts,
46 * more precisely - between given host and (one of)
47 * target hosts' address(es)
48 * (and why do you want more ?)
52 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com>
53 * I added a new flag for ip protocol number.
54 * We are using 4 as protocol number in ampr.org.
59 static const char rcsid[] =
69 #include <sys/signal.h>
70 #include <sys/socket.h>
71 #include <sys/ioctl.h>
72 #include <netinet/in.h>
73 #include <netinet/in_systm.h>
74 #include <netinet/ip.h>
76 #include <arpa/inet.h>
79 /* Tunnel interface configuration stuff */
80 static struct ifaliasreq ifra;
81 static struct ifreq ifrq;
83 /* Global descriptors */
84 int net; /* socket descriptor */
85 int tun; /* tunnel descriptor */
87 static void usage __P((void));
89 int Set_address(char *addr, struct sockaddr_in *sin)
93 bzero((char *)sin, sizeof(struct sockaddr));
94 sin->sin_family = AF_INET;
95 if((sin->sin_addr.s_addr = inet_addr(addr)) == (u_long)-1) {
96 hp = gethostbyname(addr);
98 syslog(LOG_ERR,"unknown host %s", addr);
101 sin->sin_family = hp->h_addrtype;
102 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
107 int tun_open(char *devname, struct sockaddr *ouraddr, char *theiraddr)
110 struct sockaddr_in *sin;
112 /* Open tun device */
113 tun = open (devname, O_RDWR);
115 syslog(LOG_ERR,"can't open %s - %m",devname);
120 * At first, name the interface.
122 bzero((char *)&ifra, sizeof(ifra));
123 bzero((char *)&ifrq, sizeof(ifrq));
125 strncpy(ifrq.ifr_name, devname+5, IFNAMSIZ);
126 strncpy(ifra.ifra_name, devname+5, IFNAMSIZ);
128 s = socket(AF_INET, SOCK_DGRAM, 0);
130 syslog(LOG_ERR,"can't open socket - %m");
135 * Delete (previous) adresses for interface
138 * On FreeBSD this ioctl returns error
139 * when tunN have no addresses, so - log and ignore it.
142 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
143 syslog(LOG_ERR,"SIOCDIFADDR - %m");
147 * Set interface address
149 sin = (struct sockaddr_in *)&(ifra.ifra_addr);
150 bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
151 sin->sin_len = sizeof(*sin);
154 * Set destination address
156 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
157 if(Set_address(theiraddr,sin)) {
158 syslog(LOG_ERR,"bad destination address: %s",theiraddr);
161 sin->sin_len = sizeof(*sin);
163 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
164 syslog(LOG_ERR,"can't set interface address - %m");
169 * Now, bring up the interface.
171 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
172 syslog(LOG_ERR,"can't get interface flags - %m");
176 ifrq.ifr_flags |= IFF_UP;
177 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
181 syslog(LOG_ERR,"can't set interface UP - %m");
189 void Finish(int signum)
193 syslog(LOG_INFO,"exiting");
197 s = socket(AF_INET, SOCK_DGRAM, 0);
199 syslog(LOG_ERR,"can't open socket - %m");
204 * Shut down interface.
206 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
207 syslog(LOG_ERR,"can't get interface flags - %m");
211 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
212 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
213 syslog(LOG_ERR,"can't set interface DOWN - %m");
218 * Delete adresses for interface
220 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
221 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
222 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
223 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
224 syslog(LOG_ERR,"can't delete interface's addresses - %m");
234 int main (int argc, char **argv)
238 char *devname = NULL;
239 char *point_to = NULL;
240 char *to_point = NULL;
243 char *protocol = NULL;
246 struct sockaddr t_laddr; /* Source address of tunnel */
247 struct sockaddr whereto; /* Destination of tunnel */
248 struct sockaddr wherefrom; /* Source of tunnel */
249 struct sockaddr_in *to;
251 char buf[0x2000]; /* Packets buffer */
252 struct ip *ip = (struct ip *)buf;
254 fd_set rfds, wfds, efds; /* File descriptors for select() */
255 int nfds; /* Return from select() */
258 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
277 if ((argc != 1 && argc != 2) || (devname == NULL) ||
278 (point_to == NULL) || (to_point == NULL)) {
285 protnum = atoi(protocol);
290 source = *argv++; target = *argv;
293 /* Establish logging through 'syslog' */
294 openlog("nos-tun", LOG_PID, LOG_DAEMON);
296 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
301 if(tun_open(devname, &t_laddr, to_point)) {
306 to = (struct sockaddr_in *)&whereto;
307 if(Set_address(target, to))
310 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
311 syslog(LOG_ERR,"can't open socket - %m");
316 if (Set_address(source, (struct sockaddr_in *)&wherefrom))
318 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
319 syslog(LOG_ERR, "can't bind source address - %m");
324 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
325 syslog(LOG_ERR,"can't connect to target - %m");
333 /* Install signal handlers */
334 (void)signal(SIGHUP,Finish);
335 (void)signal(SIGINT,Finish);
336 (void)signal(SIGTERM,Finish);
339 /* Set file descriptors for select() */
340 FD_ZERO(&rfds); FD_ZERO(&wfds); FD_ZERO(&efds);
341 FD_SET(tun,&rfds); FD_SET(net,&rfds);
343 nfds = select(net+10,&rfds,&wfds,&efds,NULL);
345 syslog(LOG_ERR,"interrupted select");
349 if(nfds == 0) { /* Impossible ? */
350 syslog(LOG_ERR,"timeout in select");
356 if(FD_ISSET(net,&rfds)) {
357 /* Read from socket ... */
358 len = read(net, buf, sizeof(buf));
359 /* Check if this is "our" packet */
360 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
361 /* ... skip encapsulation headers ... */
362 ipoff = (ip->ip_hl << 2);
363 /* ... and write to tun-device */
364 write(tun,buf+ipoff,len-ipoff);
368 if(FD_ISSET(tun,&rfds)) {
369 /* Read from tun ... */
370 len = read(tun, buf, sizeof(buf));
371 /* ... and send to network */
372 if(send(net, buf, len,0) <= 0) {
373 syslog(LOG_ERR,"can't send - %m");
383 "usage: nos-tun -t <tun_name> -s <source_addr> -d <dest_addr> -p <protocol_number> [<source_addr>] <target_addr>\n");