diff options
Diffstat (limited to 'ipsvd/tcpudp.c')
| -rw-r--r-- | ipsvd/tcpudp.c | 750 |
1 files changed, 750 insertions, 0 deletions
diff --git a/ipsvd/tcpudp.c b/ipsvd/tcpudp.c new file mode 100644 index 0000000..419551d --- /dev/null +++ b/ipsvd/tcpudp.c @@ -0,0 +1,750 @@ +/* Based on ipsvd utilities written by Gerrit Pape <pape@smarden.org> + * which are released into public domain by the author. + * Homepage: http://smarden.sunsite.dk/ipsvd/ + * + * Copyright (C) 2007 Denis Vlasenko. + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ + +/* TCP and UDP server are using a lot of same string constants + * We reuse them by keeping both in one source file */ + +#include "busybox.h" + +static unsigned verbose; + +static void sig_term_handler(int sig) +{ + if (verbose) + printf("%s: info: sigterm received, exit\n", applet_name); + exit(0); +} + +/* Little bloated, but tries to give accurate info how child exited. + * Makes easier to spot segfaulting children etc... */ +static void print_waitstat(unsigned pid, int wstat) +{ + unsigned e = 0; + const char *cause = "?exit"; + + if (WIFEXITED(wstat)) { + cause++; + e = WEXITSTATUS(wstat); + } else if (WIFSIGNALED(wstat)) { + cause = "signal"; + e = WTERMSIG(wstat); + } + printf("%s: info: end %d %s %d\n", applet_name, pid, cause, e); +} + + +#if ENABLE_UDPSVD +/* Based on ipsvd ipsvd-0.12.1. This udpsvd accepts all options + * which are supported by one from ipsvd-0.12.1, but not all are + * functional. See help text at the end of this file for details. + * + * Output of verbose mode matches original (modulo bugs and + * unimplemented stuff). Unnatural splitting of IP and PORT + * is retained (personally I prefer one-value "IP:PORT" notation - + * it is a natural string representation of struct sockaddr_XX). + */ + +#include "udp_io.c" + +int udpsvd_main(int argc, char **argv); +int udpsvd_main(int argc, char **argv) +{ + const char *instructs; + char *str_t, *user; + unsigned opt; + + char *remote_hostname = (char*)""; /* used if no -h */ + char *local_hostname = NULL; + char *remote_ip; + char *local_ip;// = local_ip; /* gcc */ + uint16_t local_port, remote_port; + len_and_sockaddr remote; + len_and_sockaddr *localp; + int wstat; + unsigned pid; + struct bb_uidgid_t ugid; + + enum { + OPT_v = (1 << 0), + OPT_u = (1 << 1), + OPT_l = (1 << 2), + OPT_h = (1 << 3), + OPT_p = (1 << 4), + OPT_i = (1 << 5), + OPT_x = (1 << 6), + OPT_t = (1 << 7), + }; + + opt_complementary = "-3:ph:vv"; + opt = getopt32(argc, argv, "vu:l:hpi:x:t:", + &user, &local_hostname, &instructs, &instructs, &str_t, &verbose); + if (opt & OPT_u) { + if (!get_uidgid(&ugid, user, 1)) + bb_error_msg_and_die("unknown user/group: %s", user); + } + argv += optind; + if (!argv[0][0] || LONE_CHAR(argv[0], '0')) + argv[0] = (char*)"0.0.0.0"; + + /* stdout is used for logging, don't buffer */ + setlinebuf(stdout); + bb_sanitize_stdio(); /* fd# 1,2 must be opened */ + + signal(SIGTERM, sig_term_handler); + signal(SIGPIPE, SIG_IGN); + + local_port = bb_lookup_port(argv[1], "udp", 0); + localp = xhost2sockaddr(argv[0], local_port); + /* fd #0 is the open UDP socket */ + xmove_fd(xsocket(localp->sa.sa_family, SOCK_DGRAM, 0), 0); + setsockopt_reuseaddr(0); /* crucial */ + xbind(0, &localp->sa, localp->len); + socket_want_pktinfo(0); /* needed for recv_from_to to work */ + + if (opt & OPT_u) { /* drop permissions */ + xsetgid(ugid.gid); + xsetuid(ugid.uid); + } + + if (verbose) { + /* we do it only for ":port" cosmetics... oh well */ + char *addr = xmalloc_sockaddr2dotted(&localp->sa, localp->len); + + printf("%s: info: listening on %s", applet_name, addr); + free(addr); + if (option_mask32 & OPT_u) + printf(", uid %u, gid %u", + (unsigned)ugid.uid, (unsigned)ugid.gid); + puts(", starting"); + } + + again: + /* if (recvfrom(0, NULL, 0, MSG_PEEK, &remote.sa, &localp->len) < 0) { */ + if (recv_from_to(0, NULL, 0, MSG_PEEK, &remote.sa, &localp->sa, localp->len) < 0) { + bb_perror_msg("recvfrom"); + goto again; + } + + while ((pid = fork()) < 0) { + bb_perror_msg("fork failed, sleeping"); + sleep(5); + } + if (pid > 0) { /* parent */ + while (wait_pid(&wstat, pid) < 0) + bb_perror_msg("error waiting for child"); + if (verbose) + print_waitstat(pid, wstat); + goto again; + } + + /* Child */ + + if (verbose) { + remote_ip = xmalloc_sockaddr2dotted_noport(&remote.sa, localp->len); + local_ip = xmalloc_sockaddr2dotted_noport(&localp->sa, localp->len); + + pid = getpid(); + printf("%s: info: pid %u from %s\n", applet_name, pid, remote_ip); + + if (!local_hostname) { + local_hostname = xmalloc_sockaddr2host_noport(&localp->sa, localp->len); + if (!local_hostname) + bb_error_msg_and_die("cannot look up local hostname for %s", local_ip); + } + if (opt & OPT_h) { + remote_hostname = xmalloc_sockaddr2host(&remote.sa, localp->len); + if (!remote_hostname) { + bb_error_msg("warning: cannot look up hostname for %s", remote_ip); + remote_hostname = (char*)""; + } + } + + remote_port = get_nport(&remote.sa); + remote_port = ntohs(remote_port); + printf("%s: info: %u %s:%s :%s:%s:%u\n", + applet_name, pid, local_hostname, local_ip, + remote_hostname, remote_ip, remote_port); + } + + /* Doesn't work: + * we cannot replace fd #0 - we will lose pending packet + * which is already buffered for us! And we cannot use fd #1 + * instead - it will "intercept" all following packets, but child + * do not expect data coming *from fd #1*! */ +#if 0 + /* Make it so that local addr is fixed to localp->sa + * and we don't accidentally accept packets to other local IPs. */ + /* NB: we possibly bind to the _very_ same_ address & port as the one + * already bound in parent! This seems to work in Linux. + * (otherwise we can move socket to fd #0 only if bind succeeds) */ + close(0); + set_nport(localp, htons(local_port)); + xmove_fd(xsocket(localp->sa.sa_family, SOCK_DGRAM, 0), 0); + setsockopt_reuseaddr(0); /* crucial */ + xbind(0, &localp->sa, localp->len); +#endif + + /* Make plain write to fd #1 work for the child by supplying default + * destination address. This also restricts incoming packets + * to ones coming from this remote IP. */ + xconnect(0, &remote.sa, localp->len); + dup2(0 ,1); + + signal(SIGTERM, SIG_DFL); + signal(SIGPIPE, SIG_DFL); + + argv += 2; + BB_EXECVP(argv[0], argv); + bb_perror_msg_and_die("exec '%s'", argv[0]); +} + + +/* +udpsvd [-hpvv] [-u user] [-l name] [-i dir|-x cdb] [-t sec] host port prog + +udpsvd creates an UDP/IP socket, binds it to the address host:port, +and listens on the socket for incoming datagrams. + +If a datagram is available on the socket, udpsvd conditionally starts +a program, with standard input reading from the socket, and standard +output redirected to standard error, to handle this, and possibly +more datagrams. udpsvd does not start the program if another program +that it has started before still is running. If the program exits, +udpsvd again listens to the socket until a new datagram is available. +If there are still datagrams available on the socket, the program +is restarted immediately. + +udpsvd optionally checks for special intructions depending on +the IP address or hostname of the client sending the datagram which +not yet was handled by a running program, see ipsvd-instruct(5) +for details. + +Attention: +UDP is a connectionless protocol. Most programs that handle user datagrams, +such as talkd(8), keep running after receiving a datagram, and process +subsequent datagrams sent to the socket until a timeout is reached. +udpsvd only checks special instructions for a datagram that causes a startup +of the program; not if a program handling datagrams already is running. +It doesn't make much sense to restrict access through special instructions +when using such a program. + +On the other hand, it makes perfectly sense with programs like tftpd(8), +that fork to establish a separate connection to the client when receiving +the datagram. In general it's adequate to set up special instructions for +programs that support being run by tcpwrapper. +Options + +host + host either is a hostname, or a dotted-decimal IP address, or 0. + If host is 0, udpsvd accepts datagrams to any local IP address. +port + udpsvd accepts datagrams to host:port. port may be a name from + /etc/services or a number. +prog + prog consists of one or more arguments. udpsvd normally runs prog + to handle a datagram, and possibly more, that is sent to the socket, + if there is no program that was started before by udpsvd still running + and handling datagrams. +-i dir + read instructions for handling new connections from the instructions + directory dir. See ipsvd-instruct(5) for details. +-x cdb + read instructions for handling new connections from the constant + database cdb. The constant database normally is created from + an instructions directory by running ipsvd-cdb(8). +-t sec + timeout. This option only takes effect if the -i option is given. + While checking the instructions directory, check the time of last + access of the file that matches the clients address or hostname if any, + discard and remove the file if it wasn't accessed within the last + sec seconds; udpsvd does not discard or remove a file if the user's + write permission is not set, for those files the timeout is disabled. + Default is 0, which means that the timeout is disabled. +-l name + local hostname. Do not look up the local hostname in DNS, but use name + as hostname. By default udpsvd looks up the local hostname once at startup. +-u user[:group] + drop permissions. Switch user ID to user's UID, and group ID to user's + primary GID after creating and binding to the socket. If user + is followed by a colon and a group name, the group ID is switched + to the GID of group instead. All supplementary groups are removed. +-h + Look up the client's hostname in DNS. +-p + paranoid. After looking up the client's hostname in DNS, look up + the IP addresses in DNS for that hostname, and forget the hostname + if none of the addresses match the client's IP address. You should + set this option if you use hostname based instructions. The -p option + implies the -h option. +-v + verbose. Print verbose messages to standard output. +-vv + more verbose. Print more verbose messages to standard output. +*/ +#endif + + +#if ENABLE_TCPSVD +/* Based on ipsvd ipsvd-0.12.1. This tcpsvd accepts all options + * which are supported by one from ipsvd-0.12.1, but not all are + * functional. See help text at the end of this file for details. + * + * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused. + * + * Output of verbose mode matches original (modulo bugs and + * unimplemented stuff). Unnatural splitting of IP and PORT + * is retained (personally I prefer one-value "IP:PORT" notation - + * it is a natural string representation of struct sockaddr_XX). + * + * TCPORIGDST{IP,PORT} is busybox-specific addition + */ + +#include <limits.h> +#include <linux/netfilter_ipv4.h> /* wants <limits.h> */ +#include "ipsvd_perhost.h" + +#ifdef SSLSVD +#include "matrixSsl.h" +#include "ssl_io.h" +#endif + +static unsigned max_per_host; /* originally in ipsvd_check.c */ +static unsigned cur_per_host; +static unsigned cnum; +static unsigned cmax = 30; + +/* Must match getopt32 in main! */ +enum { + OPT_c = (1 << 0), + OPT_C = (1 << 1), + OPT_i = (1 << 2), + OPT_x = (1 << 3), + OPT_u = (1 << 4), + OPT_l = (1 << 5), + OPT_E = (1 << 6), + OPT_b = (1 << 7), + OPT_h = (1 << 8), + OPT_p = (1 << 9), + OPT_t = (1 << 10), + OPT_v = (1 << 11), + OPT_V = (1 << 12), + OPT_U = (1 << 13), /* from here: sslsvd only */ + OPT_slash = (1 << 14), + OPT_Z = (1 << 15), + OPT_K = (1 << 16), +}; + +static void connection_status(void) +{ + printf("%s: info: status %u/%u\n", applet_name, cnum, cmax); +} + +static void sig_child_handler(int sig) +{ + int wstat; + int pid; + + while ((pid = wait_nohang(&wstat)) > 0) { + if (max_per_host) + ipsvd_perhost_remove(pid); + if (cnum) + cnum--; + if (verbose) + print_waitstat(pid, wstat); + } + if (verbose) + connection_status(); +} + +int tcpsvd_main(int argc, char **argv); +int tcpsvd_main(int argc, char **argv) +{ + char *str_c, *str_C, *str_b, *str_t; + char *user; + struct hcc *hccp; + const char *instructs; + char *msg_per_host = NULL; + unsigned len_per_host = len_per_host; /* gcc */ + int need_hostnames, need_remote_ip; + int pid; + int sock; + int conn; + unsigned backlog = 20; + len_and_sockaddr *lsa; + uint16_t local_port; + uint16_t remote_port = remote_port; /* gcc */ + char *local_hostname = NULL; + char *remote_hostname = (char*)""; /* "" used if no -h */ + char *local_ip = local_ip; /* gcc */ + char *remote_ip = remote_ip; /* gcc */ +#ifndef SSLSVD + struct bb_uidgid_t ugid; +#endif + + /* 3+ args, -i at most once, -p implies -h, -v is counter */ + opt_complementary = "-3:?:i--i:ph:vv"; +#ifdef SSLSVD + getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:", + &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, + &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose + ); +#else + getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:v", + &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, + &str_b, &str_t, &verbose + ); +#endif + if (option_mask32 & OPT_c) + cmax = xatou_range(str_c, 1, INT_MAX); + if (option_mask32 & OPT_C) { /* -C n[:message] */ + max_per_host = bb_strtou(str_C, &str_C, 10); + if (str_C[0]) { + if (str_C[0] != ':') + bb_show_usage(); + msg_per_host = str_C + 1; + len_per_host = strlen(msg_per_host); + } + } + if (max_per_host > cmax) + max_per_host = cmax; + if (option_mask32 & OPT_u) { + if (!get_uidgid(&ugid, user, 1)) + bb_error_msg_and_die("unknown user/group: %s", user); + } + if (option_mask32 & OPT_b) + backlog = xatou(str_b); +#ifdef SSLSVD + if (option_mask32 & OPT_U) ssluser = (char*)optarg; break; + if (option_mask32 & OPT_slash) root = (char*)optarg; break; + if (option_mask32 & OPT_Z) cert = (char*)optarg; break; + if (option_mask32 & OPT_K) key = (char*)optarg; break; +#endif + argv += optind; + if (!argv[0][0] || LONE_CHAR(argv[0], '0')) + argv[0] = (char*)"0.0.0.0"; + + /* stdout is used for logging, don't buffer */ + setlinebuf(stdout); + bb_sanitize_stdio(); /* fd# 1,2 must be opened */ + + need_hostnames = verbose || !(option_mask32 & OPT_E); + need_remote_ip = max_per_host || need_hostnames; + +#ifdef SSLSVD + sslser = user; + client = 0; + if ((getuid() == 0) && !(option_mask32 & OPT_u)) { + xfunc_exitcode = 100; + bb_error_msg_and_die("fatal: -U ssluser must be set when running as root"); + } + if (option_mask32 & OPT_u) + if (!uidgid_get(&sslugid, ssluser, 1)) { + if (errno) { + xfunc_exitcode = 100; + bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser); + } + xfunc_exitcode = 111; + bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser); + } + if (!cert) cert = "./cert.pem"; + if (!key) key = cert; + if (matrixSslOpen() < 0) + fatal("cannot initialize ssl"); + if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) { + if (client) + fatal("cannot read cert, key, or ca file"); + fatal("cannot read cert or key file"); + } + if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0) + fatal("cannot create ssl session"); +#endif + + sig_block(SIGCHLD); + signal(SIGCHLD, sig_child_handler); + signal(SIGTERM, sig_term_handler); + signal(SIGPIPE, SIG_IGN); + + if (max_per_host) + ipsvd_perhost_init(cmax); + + local_port = bb_lookup_port(argv[1], "tcp", 0); + lsa = xhost2sockaddr(argv[0], local_port); + sock = xsocket(lsa->sa.sa_family, SOCK_STREAM, 0); + setsockopt_reuseaddr(sock); /* desirable */ + xbind(sock, &lsa->sa, lsa->len); + xlisten(sock, backlog); + /* ndelay_off(sock); - it is the default I think? */ + +#ifndef SSLSVD + if (option_mask32 & OPT_u) { + /* drop permissions */ + xsetgid(ugid.gid); + xsetuid(ugid.uid); + } +#endif + + if (verbose) { + /* we do it only for ":port" cosmetics... oh well */ + char *addr = xmalloc_sockaddr2dotted(&lsa->sa, lsa->len); + + printf("%s: info: listening on %s", applet_name, addr); + free(addr); +#ifndef SSLSVD + if (option_mask32 & OPT_u) + printf(", uid %u, gid %u", + (unsigned)ugid.uid, (unsigned)ugid.gid); +#endif + puts(", starting"); + } + + /* The rest is a main accept() loop */ + + again: + hccp = NULL; + + while (cnum >= cmax) + sig_pause(); /* wait for any signal (expecting SIGCHLD) */ + + /* Accept a connection to fd #0 */ + again1: + close(0); + again2: + sig_unblock(SIGCHLD); + conn = accept(sock, &lsa->sa, &lsa->len); + sig_block(SIGCHLD); + if (conn < 0) { + if (errno != EINTR) + bb_perror_msg("accept"); + goto again2; + } + xmove_fd(conn, 0); + + if (max_per_host) { + /* Drop connection immediately if cur_per_host > max_per_host + * (minimizing load under SYN flood) */ + remote_ip = xmalloc_sockaddr2dotted_noport(&lsa->sa, lsa->len); + cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp); + if (cur_per_host > max_per_host) { + /* ipsvd_perhost_add detected that max is exceeded + * (and did not store ip in connection table) */ + free(remote_ip); + if (msg_per_host) { + /* don't block or test for errors */ + ndelay_on(0); + write(0, msg_per_host, len_per_host); + } + goto again1; + } + } + + cnum++; + if (verbose) + connection_status(); + + pid = fork(); + if (pid == -1) { + bb_perror_msg("fork"); + goto again; + } + if (pid != 0) { + /* parent */ + if (hccp) + hccp->pid = pid; + goto again; + } + + /* Child: prepare env, log, and exec prog */ + + close(sock); /* listening socket */ + /* Find out local IP peer connected to. + * Errors ignored (I'm not paranoid enough to imagine kernel + * which doesn't know local IP). */ + getsockname(0, &lsa->sa, &lsa->len); + + if (need_remote_ip) { + if (!max_per_host) + remote_ip = xmalloc_sockaddr2dotted_noport(&lsa->sa, lsa->len); + /* else it is already done */ + remote_port = get_nport(&lsa->sa); + remote_port = ntohs(remote_port); + } + + if (need_hostnames) { + if (option_mask32 & OPT_h) { + remote_hostname = xmalloc_sockaddr2host(&lsa->sa, lsa->len); + if (!remote_hostname) { + bb_error_msg("warning: cannot look up hostname for %s", remote_ip); + remote_hostname = (char*)""; + } + } + local_ip = xmalloc_sockaddr2dotted_noport(&lsa->sa, lsa->len); + local_port = get_nport(&lsa->sa); + local_port = ntohs(local_port); + if (!local_hostname) { + local_hostname = xmalloc_sockaddr2host_noport(&lsa->sa, lsa->len); + if (!local_hostname) + bb_error_msg_and_die("cannot look up local hostname for %s", local_ip); + } + } + + if (verbose) { + pid = getpid(); + printf("%s: info: pid %u from %s\n", applet_name, pid, remote_ip); + if (max_per_host) + printf("%s: info: concurrency %u %s %u/%u\n", + applet_name, pid, remote_ip, cur_per_host, max_per_host); + printf("%s: info: start %u %s:%s :%s:%s:%u\n", + applet_name, pid, + local_hostname, local_ip, + remote_hostname, remote_ip, (unsigned)remote_port); + } + + if (!(option_mask32 & OPT_E)) { + /* setup ucspi env */ + + /* Extract "original" destination addr:port + * from Linux firewall. Useful when you redirect + * an outbond connection to local handler, and it needs + * to know where it originally tried to connect */ + if (getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &lsa->sa, &lsa->len) == 0) { + char *ip = xmalloc_sockaddr2dotted_noport(&lsa->sa, lsa->len); + unsigned port = get_nport(&lsa->sa); + port = ntohs(port); + xsetenv("TCPORIGDSTIP", ip); + xsetenv("TCPORIGDSTPORT", utoa(port)); + free(ip); + } + xsetenv("PROTO", "TCP"); + xsetenv("TCPLOCALIP", local_ip); + xsetenv("TCPLOCALPORT", utoa(local_port)); + xsetenv("TCPLOCALHOST", local_hostname); + xsetenv("TCPREMOTEIP", remote_ip); + xsetenv("TCPREMOTEPORT", utoa(remote_port)); + if (option_mask32 & OPT_h) { + xsetenv("TCPREMOTEHOST", remote_hostname); + } + xsetenv("TCPREMOTEINFO", ""); + /* additional */ + if (cur_per_host > 0) + xsetenv("TCPCONCURRENCY", utoa(cur_per_host)); + } + + dup2(0, 1); + + signal(SIGTERM, SIG_DFL); + signal(SIGPIPE, SIG_DFL); + signal(SIGCHLD, SIG_DFL); + sig_unblock(SIGCHLD); + + argv += 2; +#ifdef SSLSVD + strcpy(id, utoa(pid); + ssl_io(0, argv); +#else + BB_EXECVP(argv[0], argv); +#endif + bb_perror_msg_and_die("exec '%s'", argv[0]); +} + +/* +tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name] + [-i dir|-x cdb] [ -t sec] host port prog + +tcpsvd creates a TCP/IP socket, binds it to the address host:port, +and listens on the socket for incoming connections. + +On each incoming connection, tcpsvd conditionally runs a program, +with standard input reading from the socket, and standard output +writing to the socket, to handle this connection. tcpsvd keeps +listening on the socket for new connections, and can handle +multiple connections simultaneously. + +tcpsvd optionally checks for special instructions depending +on the IP address or hostname of the client that initiated +the connection, see ipsvd-instruct(5). + +host + host either is a hostname, or a dotted-decimal IP address, + or 0. If host is 0, tcpsvd accepts connections to any local + IP address. + * busybox accepts IPv6 addresses and host:port pairs too + In this case second parameter is ignored +port + tcpsvd accepts connections to host:port. port may be a name + from /etc/services or a number. +prog + prog consists of one or more arguments. For each connection, + tcpsvd normally runs prog, with file descriptor 0 reading from + the network, and file descriptor 1 writing to the network. + By default it also sets up TCP-related environment variables, + see tcp-environ(5) +-i dir + read instructions for handling new connections from the instructions + directory dir. See ipsvd-instruct(5) for details. + * ignored by busyboxed version +-x cdb + read instructions for handling new connections from the constant database + cdb. The constant database normally is created from an instructions + directory by running ipsvd-cdb(8). + * ignored by busyboxed version +-t sec + timeout. This option only takes effect if the -i option is given. + While checking the instructions directory, check the time of last access + of the file that matches the clients address or hostname if any, discard + and remove the file if it wasn't accessed within the last sec seconds; + tcpsvd does not discard or remove a file if the user's write permission + is not set, for those files the timeout is disabled. Default is 0, + which means that the timeout is disabled. + * ignored by busyboxed version +-l name + local hostname. Do not look up the local hostname in DNS, but use name + as hostname. This option must be set if tcpsvd listens on port 53 + to avoid loops. +-u user[:group] + drop permissions. Switch user ID to user's UID, and group ID to user's + primary GID after creating and binding to the socket. If user is followed + by a colon and a group name, the group ID is switched to the GID of group + instead. All supplementary groups are removed. +-c n + concurrency. Handle up to n connections simultaneously. Default is 30. + If there are n connections active, tcpsvd defers acceptance of a new + connection until an active connection is closed. +-C n[:msg] + per host concurrency. Allow only up to n connections from the same IP + address simultaneously. If there are n active connections from one IP + address, new incoming connections from this IP address are closed + immediately. If n is followed by :msg, the message msg is written + to the client if possible, before closing the connection. By default + msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg. + + For each accepted connection, the current per host concurrency is + available through the environment variable TCPCONCURRENCY. n and msg + can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5). + By default tcpsvd doesn't keep track of connections. +-h + Look up the client's hostname in DNS. +-p + paranoid. After looking up the client's hostname in DNS, look up the IP + addresses in DNS for that hostname, and forget about the hostname + if none of the addresses match the client's IP address. You should + set this option if you use hostname based instructions. The -p option + implies the -h option. + * ignored by busyboxed version +-b n + backlog. Allow a backlog of approximately n TCP SYNs. On some systems n + is silently limited. Default is 20. +-E + no special environment. Do not set up TCP-related environment variables. +-v + verbose. Print verbose messsages to standard output. +-vv + more verbose. Print more verbose messages to standard output. + * no difference between -v and -vv in busyboxed version +*/ +#endif |