2 * General front end for stream and datagram IP services. This program logs
3 * the remote host name and then invokes the real daemon. For example,
4 * install as /usr/etc/{tftpd,fingerd,telnetd,ftpd,rlogind,rshd,rexecd},
5 * after saving the real daemons in the directory specified with the
6 * REAL_DAEMON_DIR macro. This arrangement requires that the network daemons
7 * are started by inetd or something similar. Connections and diagnostics
8 * are logged through syslog(3).
10 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
14 static char sccsid[] = "@(#) tcpd.c 1.10 96/02/11 17:01:32";
17 /* System libraries. */
19 #include <sys/types.h>
20 #include <sys/param.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
28 #ifndef MAXPATHNAMELEN
29 #define MAXPATHNAMELEN BUFSIZ
33 #define STDIN_FILENO 0
38 #include "patchlevel.h"
41 int allow_severity = SEVERITY; /* run-time adjustable */
42 int deny_severity = LOG_WARNING; /* ditto */
48 struct request_info request;
49 char path[MAXPATHNAMELEN];
51 /* Attempt to prevent the creation of world-writable files. */
58 * If argv[0] is an absolute path name, ignore REAL_DAEMON_DIR, and strip
59 * argv[0] to its basename.
62 if (argv[0][0] == '/') {
63 strcpy(path, argv[0]);
64 argv[0] = strrchr(argv[0], '/') + 1;
66 sprintf(path, "%s/%s", REAL_DAEMON_DIR, argv[0]);
69 /* Prevent aimless recursion when the daemon is run as /bin/tcpd */
70 if (STR_EQ(argv[0], "tcpd")) {
73 if (argv[0][0] == '/') {
74 strcpy(path, argv[0]);
75 argv[0] = strrchr(argv[0], '/') + 1;
77 sprintf(path, "%s/%s", REAL_DAEMON_DIR, argv[0]);
83 * Open a channel to the syslog daemon. Older versions of openlog()
84 * require only two arguments.
88 (void) openlog(argv[0], LOG_PID, FACILITY);
90 (void) openlog(argv[0], LOG_PID);
94 * Find out the endpoint addresses of this conversation. Host name
95 * lookups and double checks will be done on demand.
98 request_init(&request, RQ_DAEMON, argv[0], RQ_FILE, STDIN_FILENO, 0);
102 * Optionally look up and double check the remote host name. Sites
103 * concerned with security may choose to refuse connections from hosts
104 * that pretend to have someone elses host name.
108 if (STR_EQ(eval_hostname(request.client), paranoid))
113 * The BSD rlogin and rsh daemons that came out after 4.3 BSD disallow
114 * socket options at the IP level. They do so for a good reason.
115 * Unfortunately, we cannot use this with SunOS 4.1.x because the
116 * getsockopt() system call can panic the system.
119 #ifdef KILL_IP_OPTIONS
120 fix_options(&request);
124 * Check whether this host can access the service in argv[0]. The
125 * access-control code invokes optional shell commands as specified in
126 * the access-control tables.
130 if (!hosts_access(&request))
134 /* Report request and invoke the real daemon program. */
136 syslog(allow_severity, "connect from %s", eval_client(&request));
138 (void) execv(path, argv);
139 syslog(LOG_ERR, "error: cannot execute %s: %m", path);
140 clean_exit(&request);