options.c

OpenVPN is a robust and highly flexible tunneling application that uses all of the encryption, authe

/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2004 James Yonan <[e-mail]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * 2004-01-28: Added Socks5 proxy support
 *   (Christof Meerwald, http://cmeerw.org)
 */

#ifdef WIN32
#include "config-win32.h"
#else
#include "config.h"
#endif

#include "syshead.h"

#include "buffer.h"
#include "error.h"
#include "common.h"
#include "shaper.h"
#include "crypto.h"
#include "ssl.h"
#include "options.h"
#include "misc.h"
#include "socket.h"
#include "packet_id.h"
#include "win32.h"
#include "push.h"

#include "memdbg.h"

const char title_string[] =
  PACKAGE_STRING
  " " TARGET_ALIAS
#ifdef USE_CRYPTO
#ifdef USE_SSL
  " [SSL]"
#else
  " [CRYPTO]"
#endif
#endif
#ifdef USE_LZO
  " [LZO]"
#endif
#if EPOLL
  " [EPOLL]"
#endif
#ifdef USE_PTHREAD
  " [PTHREAD]"
#endif
  " built on " __DATE__
;

static const char usage_message[] =
  "%s\n"
  "\n"
  "General Options:\n"
  "--config file   : Read configuration options from file.\n"
  "--help          : Show options.\n"
  "--version       : Show copyright and version information.\n"
  "\n"
  "Tunnel Options:\n"
  "--local host    : Local host name or ip address.\n"
  "--remote host [port] : Remote host name or ip address.\n"
  "--remote-random : If multiple --remote options specified, choose one randomly.\n"
  "--mode m        : Major mode, m = 'p2p' (default, point-to-point) or 'server'.\n"
  "--proto p       : Use protocol p for communicating with peer.\n"
  "                  p = udp (default), tcp-server, or tcp-client\n"
  "--connect-retry n : For --proto tcp-client, number of seconds to wait\n"
  "                  between connection retries (default=%d).\n"
  "--http-proxy s p [up]: Connect to remote host through an HTTP proxy at address\n"
  "                  s and port p.  If proxy authentication is required, up is a\n"
  "                  file containing username/password on 2 lines.\n"
  "--http-proxy-retry : Retry indefinitely on HTTP proxy errors.\n"
  "--socks-proxy s [p]: Connect to remote host through a Socks5 proxy at address\n"
  "                  s and port p (default port = 1080).\n"
  "--socks-proxy-retry : Retry indefinitely on Socks proxy errors.\n"
  "--resolv-retry n: If hostname resolve fails for --remote, retry\n"
  "                  resolve for n seconds before failing (disabled by default).\n"
  "                  Set n=\"infinite\" to retry indefinitely.\n"
  "--float         : Allow remote to change its IP address/port, such as through\n"
  "                  DHCP (this is the default if --remote is not used).\n"
  "--ipchange cmd  : Execute shell command cmd on remote ip address initial\n"
  "                  setting or change -- execute as: cmd ip-address port#\n"
  "--port port     : TCP/UDP port # for both local and remote.\n"
  "--lport port    : TCP/UDP port # for local (default=%d).\n"
  "--rport port    : TCP/UDP port # for remote (default=%d).\n"
  "--nobind        : Do not bind to local address and port.\n"
  "--dev tunX|tapX : tun/tap device (X can be omitted for dynamic device.\n"
  "--dev-type dt   : Which device type are we using? (dt = tun or tap) Use\n"
  "                  this option only if the tun/tap device used with --dev\n"
  "                  does not begin with \"tun\" or \"tap\".\n"
  "--dev-node node : Explicitly set the device node rather than using\n"
  "                  /dev/net/tun, /dev/tun, /dev/tap, etc.\n"
  "--tun-ipv6      : Build tun link capable of forwarding IPv6 traffic.\n"
  "--ifconfig l rn : TUN: configure device to use IP address l as a local\n"
  "                  endpoint and rn as a remote endpoint.  l & rn should be\n"
  "                  swapped on the other peer.  l & rn must be private\n"
  "                  addresses outside of the subnets used by either peer.\n"
  "                  TAP: configure device to use IP address l as a local\n"
  "                  endpoint and rn as a subnet mask.\n"
  "--ifconfig-noexec : Don't actually execute ifconfig/netsh command, instead\n"
  "                    pass --ifconfig parms by environment to scripts.\n"
  "--ifconfig-nowarn : Don't warn if the --ifconfig option on this side of the\n"
  "                    connection doesn't match the remote side.\n"
  "--route network [netmask] [gateway] [metric] :\n"
  "                  Add route to routing table after connection\n"
  "                  is established.  Multiple routes can be specified.\n"
  "                  netmask default: 255.255.255.255\n"
  "                  gateway default: taken from --route-gateway or --ifconfig\n"
  "                  Specify default by leaving blank or setting to \"nil\".\n"
  "--route-gateway gw : Specify a default gateway for use with --route.\n"
  "--route-delay n : Delay n seconds after connection initiation before\n"
  "                  adding routes (may be 0).  If not specified, routes will\n"
  "                  be added immediately after tun/tap open.\n"
  "--route-up cmd  : Execute shell cmd after routes are added.\n"
  "--route-noexec  : Don't add routes automatically.  Instead pass routes to\n"
  "                  --route-up script using environmental variables.\n"
  "--redirect-gateway ['local']: (Experimental) Automatically execute routing\n"
  "                  commands to redirect all outgoing IP traffic through the\n"
  "                  VPN.  Add 'local' flag if both OpenVPN servers are directly\n"
  "                  connected via a common subnet, such as with wireless.\n"
  "--setenv name value : Set a custom environmental variable to pass to script.\n"
  "--shaper n      : Restrict output to peer to n bytes per second.\n"
  "--inactive n    : Exit after n seconds of inactivity on tun/tap device.\n"
  "--ping-exit n   : Exit if n seconds pass without reception of remote ping.\n"
  "--ping-restart n: Restart if n seconds pass without reception of remote ping.\n"
  "--ping-timer-rem: Run the --ping-exit/--ping-restart timer only if we have a\n"
  "                  remote address.\n"
  "--ping n        : Ping remote once every n seconds over TCP/UDP port.\n"
  "--persist-tun   : Keep tun/tap device open across SIGUSR1 or --ping-restart.\n"
  "--persist-remote-ip : Keep remote IP address across SIGUSR1 or --ping-restart.\n"
  "--persist-local-ip  : Keep local IP address across SIGUSR1 or --ping-restart.\n"
  "--persist-key   : Don't re-read key files across SIGUSR1 or --ping-restart.\n"
#if PASSTOS_CAPABILITY
  "--passtos       : TOS passthrough (applies to IPv4 only).\n"
#endif
  "--tun-mtu n     : Take the tun/tap device MTU to be n and derive the\n"
  "                  TCP/UDP MTU from it (default=%d).\n"
  "--tun-mtu-extra n : Assume that tun/tap device might return as many\n"
  "                  as n bytes more than the tun-mtu size on read\n"
  "                  (default TUN=0 TAP=%d).\n"
  "--link-mtu n    : Take the TCP/UDP device MTU to be n and derive the tun MTU\n"
  "                  from it.\n"
  "--mtu-disc type : Should we do Path MTU discovery on TCP/UDP channel?\n"
  "                  'no'    -- Never send DF (Don't Fragment) frames\n"
  "                  'maybe' -- Use per-route hints\n"
  "                  'yes'   -- Always DF (Don't Fragment)\n"
  "--mtu-test      : Empirically measure and report MTU.\n"
  "--fragment max  : Enable internal datagram fragmentation so that no UDP\n"
  "                  datagrams are sent which are larger than max bytes.\n"
  "                  Adds 4 bytes of overhead per datagram.\n"
  "--mssfix [n]    : Set upper bound on TCP MSS, default = tun-mtu size\n"
  "                  or --fragment max value, whichever is lower.\n"
  "--sndbuf size   : Set the TCP/UDP send buffer size.\n"
  "--rcvbuf size   : Set the TCP/UDP receive buffer size.\n"
  "--txqueuelen n  : Set the tun/tap TX queue length to n (Linux only).\n"
  "--mlock         : Disable Paging -- ensures key material and tunnel\n"
  "                  data will never be written to disk.\n"
  "--up cmd        : Shell cmd to execute after successful tun device open.\n"
  "                  Execute as: cmd tun/tap-dev tun-mtu link-mtu \\\n"
  "                              ifconfig-local-ip ifconfig-remote-ip\n"
  "                  (pre --user or --group UID/GID change)\n"
  "--up-delay      : Delay tun/tap open and possible --up script execution\n"
  "                  until after TCP/UDP connection establishment with peer.\n"
  "--down cmd      : Shell cmd to run after tun device close.\n"
  "                  (post --user/--group UID/GID change and/or --chroot)\n"
  "                  (script parameters are same as --up option)\n"
  "--up-restart    : Run up/down scripts for all restarts including those\n"
  "                  caused by --ping-restart or SIGUSR1\n"
  "--user user     : Set UID to user after initialization.\n"
  "--group group   : Set GID to group after initialization.\n"
  "--chroot dir    : Chroot to this directory after initialization.\n"
  "--cd dir        : Change to this directory before initialization.\n"
  "--daemon [name] : Become a daemon after initialization.\n"
  "                  The optional 'name' parameter will be passed\n"
  "                  as the program name to the system logger.\n"
  "--inetd [name] ['wait'|'nowait'] : Run as an inetd or xinetd server.\n"
  "                  See --daemon above for a description of the 'name' parm.\n"
  "--log file      : Output log to file which is created/truncated on open.\n"
  "--log-append file : Append log to file, or create file if nonexistent.\n"
  "--writepid file : Write main process ID to file.\n"
  "--nice n        : Change process priority (>0 = lower, <0 = higher).\n"
#ifdef USE_PTHREAD
  "--nice-work n   : Change thread priority of work thread.  The work\n"
  "                  thread is used for background processing such as\n"
  "                  RSA key number crunching.\n"
#endif
  "--verb n        : Set output verbosity to n (default=%d):\n"
  "                  (Level 3 is recommended if you want a good summary\n"
  "                  of what's happening without being swamped by output).\n"
  "                : 0 -- no output except fatal errors\n"
  "                : 1 -- startup info + connection initiated messages +\n"
  "                       non-fatal encryption & net errors\n"
  "                : 2 -- show TLS negotiations\n"
  "                : 3 -- show extra TLS info + --gremlin net outages +\n"
  "                       adaptive compress info\n"
  "                : 4 -- show parameters\n"
  "                : 5 -- show 'RrWw' chars on console for each packet sent\n"
  "                       and received from TCP/UDP (caps) or tun/tap (lc)\n"
  "                : 6 to 11 -- debug messages of increasing verbosity\n"
  "--mute n        : Log at most n consecutive messages in the same category.\n"
  "--status file n : Write operational status to file every n seconds.\n"
  "--disable-occ   : Disable options consistency check between peers.\n"
  "--gremlin       : Simulate dropped & corrupted packets + network outages\n"
  "                  to test robustness of protocol (for debugging only).\n"
#ifdef USE_LZO
  "--comp-lzo      : Use fast LZO compression -- may add up to 1 byte per\n"
  "                  packet for uncompressible data.\n"
  "--comp-noadapt  : Don't use adaptive compression when --comp-lzo\n"
  "                  is specified.\n"
#endif
#if P2MP
  "\n"
  "Multi-Client Server options (when --mode server is used):\n"
  "--push \"option\" : Push a config file option back to the peer for remote\n"
  "                  execution.  Peer must specify --pull in its config file.\n"
  "--push-reset    : Don't inherit global push list for specific\n"
  "                  client instance.\n"
  "--ifconfig-pool start-IP end-IP : Set aside a pool of subnets to be\n"
  "                  dynamically allocated to connecting clients.\n"
  "--ifconfig-push local remote-netmask : Push an ifconfig option to remote,\n"
  "                  overrides --ifconfig-pool dynamic allocation.\n"
  "                  Must be associated with a specific client instance.\n"
  "--iroute network [netmask] : Route subnet to client.\n"
  "                  Sets up internal routes only, and must be\n"
  "                  associated with a specific client instance.\n"
  "--client-to-client : Internally route client-to-client traffic.\n"
  "--duplicate-cn  : Allow multiple clients with the same common name to\n"
  "                  concurrently connect.\n"
  "--client-connect cmd : Run script cmd on client connection.\n"
  "--client-disconnect cmd : Run script cmd on client disconnection.\n"
  "--client-config-dir dir : Directory for custom client config files.\n"
  "--tmp-dir dir   : Temporary directory, used for --client-connect return file.\n"
  "--hash-size r v : Set the size of the real address hash table to r and the\n"
  "                  virtual address table to v.\n"
  "--bcast-buffers n : Allocate n broadcast buffers.\n"
  "--connect-freq n s : Allow a maximum of n new connections per s seconds.\n"
  "--learn-address cmd : Run script cmd to validate client virtual addresses.\n"
  "\n"
  "Client options (when connecting to a multi-client server):\n"
  "--pull          : Accept certain config file options from the peer as if they\n"
  "                  were part of the local config file.  Must be specified\n"
  "                  when connecting to a '--mode server' remote host.\n"
#endif
#ifdef USE_CRYPTO
  "\n"
  "Data Channel Encryption Options (must be compatible between peers):\n"
  "(These options are meaningful for both Static Key & TLS-mode)\n"
  "--secret f [d]  : Enable Static Key encryption mode (non-TLS).\n"
  "                  Use shared secret file f, generate with --genkey.\n"
  "                  The optional d parameter controls key directionality.\n"
  "                  If d is specified, use separate keys for each\n"
  "                  direction, set d=0 on one side of the connection,\n"
  "                  and d=1 on the other side.\n"
  "--auth alg      : Authenticate packets with HMAC using message\n"
  "                  digest algorithm alg (default=%s).\n"
  "                  (usually adds 16 or 20 bytes per packet)\n"
  "                  Set alg=none to disable authentication.\n"
  "--cipher alg    : Encrypt packets with cipher algorithm alg\n"
  "                  (default=%s).\n"
  "                  Set alg=none to disable encryption.\n"
#ifdef HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH
  "--keysize n     : Size of cipher key in bits (optional).\n"
  "                  If unspecified, defaults to cipher-specific default.\n"
#endif
  "--engine        : Enable OpenSSL hardware crypto engine functionality.\n"
  "--no-replay     : Disable replay protection.\n"
  "--replay-window n [t] : Use a replay protection sliding window of size n\n"
  "                        and a time window of t seconds.\n"
  "                        Default n=%d t=%d\n"
  "--no-iv         : Disable cipher IV -- only allowed with CBC mode ciphers.\n"
  "--replay-persist file : Persist replay-protection state across sessions\n"
  "                  using file.\n"
  "--test-crypto   : Run a self-test of crypto features enabled.\n"
  "                  For debugging only.\n"
#ifdef USE_SSL
  "\n"
  "TLS Key Negotiation Options:\n"
  "(These options are meaningful only for TLS-mode)\n"
  "--tls-server    : Enable TLS and assume server role during TLS handshake.\n"
  "--tls-client    : Enable TLS and assume client role during TLS handshake.\n"
  "--key-method m  : Data channel key exchange method.  m should be a method\n"
  "                  number, such as 1 (default), 2, etc.\n"
  "--ca file       : Certificate authority file in .pem format containing\n"
  "                  root certificate.\n"
  "--dh file       : File containing Diffie Hellman parameters\n"
  "                  in .pem format (for --tls-server only).\n"
  "                  Use \"openssl dhparam -out dh1024.pem 1024\" to generate.\n"
  "--cert file     : Local certificate in .pem format -- must be signed\n"
  "                  by a Certificate Authority in --ca file.\n"
  "--key file      : Local private key in .pem format.\n"
  "--tls-cipher l  : A list l of allowable TLS ciphers separated by : (optional).\n"
  "                : Use --show-tls to see a list of supported TLS ciphers.\n"
  "--tls-timeout n : Packet retransmit timeout on TLS control channel\n"
  "                  if no ACK from remote within n seconds (default=%d).\n"
  "--reneg-bytes n : Renegotiate data chan. key after n bytes sent and recvd.\n"
  "--reneg-pkts n  : Renegotiate data chan. key after n packets sent and recvd.\n"
  "--reneg-sec n   : Renegotiate data chan. key after n seconds (default=%d).\n"
  "--hand-window n : Data channel key exchange must finalize within n seconds\n"
  "                  of handshake initiation by any peer (default=%d).\n"
  "--tran-window n : Transition window -- old key can live this many seconds\n"
  "                  after new key renegotiation begins (default=%d).\n"
  "--single-session: Allow only one session (reset state on restart).\n"
  "--tls-auth f [d]: Add an additional layer of authentication on top of the TLS\n"
  "                  control channel to protect against DoS attacks.\n"
  "                  f (required) is a shared-secret passphrase file.\n"
  "                  The optional d parameter controls key directionality,\n"
  "                  see --secret option for more info.\n"
  "--askpass       : Get PEM password from controlling tty before we daemonize.\n"
  "--crl-verify crl: Check peer certificate against a CRL.\n"
  "--tls-verify cmd: Execute shell command cmd to verify the X509 name of a\n"
  "                  pending TLS connection that has otherwise passed all other\n"
  "                  tests of certification.  cmd should return 0 to allow\n"
  "                  TLS handshake to proceed, or 1 to fail.  (cmd is\n"
  "                  executed as 'cmd certificate_depth X509_NAME_oneline')\n"
  "--tls-remote x509name: Accept connections only from a host with X509 name\n"
  "                  x509name. The remote host must also pass all other tests\n"
  "                  of verification.\n"
#endif				/* USE_SSL */
  "\n"
  "SSL Library information:\n"
  "--show-ciphers  : Show cipher algorithms to use with --cipher option.\n"
  "--show-digests  : Show message digest algorithms to use with --auth option.\n"
#ifdef USE_SSL
  "--show-tls      : Show all TLS ciphers (TLS used only as a control channel).\n"
#endif
#ifdef WIN32
  "\n"
  "Windows Specific:\n"
  "--show-adapters : Show all TAP-Win32 adapters.\n"
  "--ip-win32 method : When using --ifconfig on Windows, set TAP-Win32 adapter\n"
  "                    IP address using method = manual, netsh, ipapi, or\n"
  "                    dynamic (default = ipapi).\n"
  "                    Dynamic method allows two optional parameters:\n"
  "                    offset: DHCP server address offset (> -256 and < 256).\n"
  "                            If 0, use network address, if >0, take nth\n"
  "                            address forward from network address, if <0,\n"
  "                            take nth address backward from broadcast\n"
  "                            address.\n"
  "                            Default is 0.\n"
  "                    lease-time: Lease time in seconds.\n"
  "                                Default is one year.\n"
  "--dhcp-option type [parm] : Set extended TAP-Win32 properties, must\n"
  "                    be used with --ip-win32 dynamic.  For options\n"
  "                    which allow multiple addresses,\n"
  "                    --dhcp-option must be repeated.\n"
  "                    DOMAIN name : Set DNS suffix\n"
  "                    DNS addr    : Set domain name server address(es)\n"
  "                    NTP         : Set NTP server address(es)\n"
  "                    NBDD        : Set NBDD server address(es)\n"
  "                    WINS addr   : Set WINS server address(es)\n"
  "                    NBT type    : Set NetBIOS over TCP/IP Node type\n"
  "                                  1: B, 2: P, 4: M, 8: H\n"
  "                    NBS id      : Set NetBIOS scope ID\n"
  "--tap-sleep n   : Sleep for n seconds after TAP adapter open before\n"
  "                  attempting to set adapter properties.\n"
  "--show-valid-subnets : Show valid subnets for --dev tun emulation.\n" 
  "--pause-exit         : When run from a console window, pause before exiting.\n"
  "--service ex [0|1]   : For use when OpenVPN is being instantiated by a\n"
  "                       service, and should not be used directly by end-users.\n"
  "                       ex is the name of an event object which, when\n"
  "                       signaled, will cause OpenVPN to exit.  A second\n"
  "                       optional parameter controls the initial state of ex.\n"
#endif
  "\n"
  "Generate a random key (only for non-TLS static key encryption mode):\n"
  "--genkey        : Generate a random key to be used as a shared secret,\n"
  "                  for use with the --secret option.\n"
  "--secret file   : Write key to file.\n"
#endif				/* USE_CRYPTO */
#ifdef TUNSETPERSIST
  "\n"
  "Tun/tap config mode (available with linux 2.4+):\n"
  "--mktun         : Create a persistent tunnel.\n"
  "--rmtun         : Remove a persistent tunnel.\n"
  "--dev tunX|tapX : tun/tap device\n"
  "--dev-type dt   : Device type.  See tunnel options above for details.\n"
#endif
 ;

/*
 * This is where the options defaults go.
 * Any option not explicitly set here
 * will be set to 0.
 */
void
init_options (struct options *o)
{
  CLEAR (*o);
  gc_init (&o->gc);
  o->mode = MODE_POINT_TO_POINT;
  o->proto = PROTO_UDPv4;
  o->connect_retry_seconds = 5;
#ifdef TUNSETPERSIST