inetd Daemon

The inetd daemon is invoked at startup time and is now configured by using smf. The configuration was previously performed by /etc/inet/inetd.conf file. For more information, see the inetd(8), and smf(7) man pages.

Use inetconv to convert the configuration file content into SMF format services, and then manage these services using inetadm and svcadm. For more information, see the inetconv(8), inetadm(8) and svcadm(8) man pages.

The inetd daemon polls each socket, waiting for a connection request to the service corresponding to that socket. For SOCK_STREAM type sockets, inetd accepts using accept() on the listening socket, forks using fork(), duplicates using dup() the new socket to file descriptors 0 and 1 (stdin and stdout), closes other open file descriptors, and executes using exec the appropriate server. For more information, see the accept(3C), fork(2), dup(2), and exec(2) man page.

The primary benefit of using inetd is that services not in use do not consume system resources. A secondary benefit is that inetd does most of the work to establish a connection. The server started by inetd has the socket connected to its client on file descriptors 0 and 1. The server can immediately read, write, send, or receive. Servers can use buffered I/O as provided by the stdio conventions, as long as the servers use fflush when appropriate. For more information, see the fflush(3C) man page.

The getpeername() routine returns the address of the peer (process) connected to a socket. This routine is useful in servers started by inetd. For example, you could use this routine to log the Internet address such as fec0::56:a00:20ff:fe7d:3dd2, which is conventional for representing the IPv6 address of a client. An inetd server could use the following sample code:

struct sockaddr_storage name;
int namelen = sizeof (name);
char abuf[INET6_ADDRSTRLEN];
struct in6_addr addr6;
struct in_addr addr;

if (getpeername(fd, (struct sockaddr *) &name, &namelen) == -1) {
    perror("getpeername");
    exit(1);
} else {
    addr = ((struct sockaddr_in *)&name)->sin_addr;
    addr6 = ((struct sockaddr_in6 *)&name)->sin6_addr;
    if (name.ss_family == AF_INET) {
            (void) inet_ntop(AF_INET, &addr, abuf, sizeof (abuf));
    } else if (name.ss_family == AF_INET6 &&
               IN6_IS_ADDR_V4MAPPED(&addr6)) {
            /* this is a IPv4-mapped IPv6 address */
            IN6_MAPPED_TO_IN(&addr6, &addr);
            (void) inet_ntop(AF_INET, &addr, abuf, sizeof (abuf));
    } else if (name.ss_family == AF_INET6) {
            (void) inet_ntop(AF_INET6, &addr6, abuf, sizeof (abuf));

    }
    syslog("Connection from %s\n", abuf);
}