path: root/doc/afclient.1

.TH afclient 1 "apf 0.8.5" Jeremian
.SH NAME
afclient \- active port forwarder client
.SH SYNOPSIS
.B afclient [
.I options
.B ] -n
.I servername
.B -p
.I portnum
.SH DESCRIPTION
.B Afclient
is a port forwarding program designed to be efficient and easy to use. It connects to
.B afserver
to listenport (default listenport is 50126) and after a successful authorization
.B afclient
redirects all the data to the specified destination host:port.
.SH "EXAMPLES"
.B afclient -n servername -p 22
  program connects to servername:50126 and redirects data to local port 22 (becomes a daemon)

.B afclient -n servername -p 22 -v
  the same as above, but verbose mode is enabled (program won't enter daemon mode)

.B afclient -n servername -r
  program connects to servername:50126 in remote administration mode
.SH OPTIONS
.I "Basic options"

.B -n, --servername NAME
  name of the host, where
.I afserver
is running (required)

.B -m, --manageport PORT
  manage port number - server must be listening on it (default: 50126)

.B -d, --hostname NAME
  the name of this host/remote host - the final destination of the packets (default: the name returned by hostname function)

.B -p, --portnum PORT
  the port we are forwarding connection to (required)

.B --localname NAME
  local machine name for connection with afserver (used to bind socket to different interfaces)

.B --localport NAME
  local port name for connection with afserver (used to bind socket to different addressees)

.B --localdesname NAME
  local machine name for connections with destination application (used to bind socket to different interfaces)

.B -V, --version
  display version number

.B -h, --help
  prints help screen

.I Authorization

.B -i, --id STRING
  sends the id string to afserver
  
.B --pass PASSWORD
  set the password used for client identification (default: no password)

.B --ignorepkeys
  ignore invalid server's public keys

.I Configuration

.B -k, --keyfile FILE
  the name of the file with RSA key (default: client.rsa)

.B -c, --cerfile
  the name of the file with certificate (default: no certificate used)

.B -f, --cfgfile FILE
  the name of the file with the configuration for the
.I afclient

.B -s, --storefile
  the name of the file with stored public keys (default: known_hosts)
  
.B -D, --dateformat FORMAT
  format of the date printed in logs (see 'man strftime' for details) (default: %d.%m.%Y %H:%M:%S)

.B -K, --keep-alive N
  send keepalive packets every N seconds (default: not send keepalive packets)

.I Auto-reconnection

.B --ar-start
  enable auto-reconnection when afserver is not reachable on start (default: disabled)

.B --ar-quit
  enable auto-reconnection after normal afserver quit (default: disabled)

.B --noar
  disable auto-reconnection after premature afserver quit (default: enabled)

.B -A, --ar-tries N
  try N times to reconnect (default: unlimited)

.B -T, --ar-delay N
  wait N seconds between reconnect tries (default: 5)

.I Modes

.B -u, --udpmode
  udp mode - client will use udp protocol to communicate with the hostname:portnum

.B -U, --reverseudp
  reverse udp forwarding. Udp packets will be forwarded from hostname:portnum to the server name:manageport
  
.B -r, --remoteadmin
  remote administration mode. (using '-p PORT' will force afclient to use port rather than stdin-stdout)

.I Logging

.B -o, --log LOGCMD
  log choosen information to file/socket

.B -v, --verbose
  to be verbose - program won't enter the daemon mode (use several times for greater effect)

.I "IP family"

.B -4, --ipv4
  use ipv4 only

.B -6, --ipv6
  use ipv6 only

.I Modules

.B -l, --load
  load a module for user's packets filtering

.B -L, --Load
  load a module for service's packets filtering

.SH "REMOTE ADMINISTRATION"

Remote administration mode is enabled by
.B '-r, --remoteadmin'
option. Required options:
.B '-n, --servername NAME'

After successful authorization stdin/stdout are used to communicate with user. All the commands parsing is done by
.BR afserver .
Commands guaranteed to be available:

.B help
  display help

.B lcmd
  lists available commands

.B quit
  quit connection

For list of all available commands take a look at
.BR afserver (1).

When 
.B '-p, --portnum PORT'
is used,
.B afclient
listens for connection from user at NAME:PORT. NAME is set by
.B '-d, --hostname'
option or hostname() function, when the option is missing.

When user quits (close the connection or send
.B 'quit'
command),
.B afclient
exits.

.SH "LOGCMD FORMAT"

.B LOGCMD
has the following synopsis:
.B target,description,msgdesc

Where
.B target
is
.B file
or
.B sock

.B description
is
.B filename
or
.B host,port

and
.B msgdesc
is the subset of:

.B LOG_T_ALL,
.B LOG_T_USER,
.B LOG_T_CLIENT,
.B LOG_T_INIT,
.B LOG_T_MANAGE,
.B LOG_T_MAIN,
.B LOG_I_ALL,
.B LOG_I_CRIT,
.B LOG_I_DEBUG,
.B LOG_I_DDEBUG,
.B LOG_I_INFO,
.B LOG_I_NOTICE,
.B LOG_I_WARNING,
.B LOG_I_ERR

written without spaces.

  Example:

  file,logfile,LOG_T_USER,LOG_T_CLIENT,LOG_I_INFO,LOG_I_NOTICE

.SH MODULES

.B Afclient
can use external modules for user's packets filtering
.RB ( "'-l,  --load'" )
and service's packets filtering
.RB ( "'-L, --Load'" ).
Module file has to declare three functions:

.BI "char* info(" void );
  
  info() return values:
  - info about module

  Example:

  char*
  info(void)
  {      
    return "Module tester v0.1";
  }    
         
.BI "int allow(char* " host ", char* " port );
       
  allow() return values:
  0 - allow to connect
  !0 - drop the connection
         
  Example:
       
  int    
  allow(char* host, char* port)
  {    
    return 0; /* allow to connect */
  }
       
.BI "int filter(char* " host ", unsigned char* " message ", int* " length );

  filter() return values:
  0 - allow to transfer 
  1 - drop the packet
  2 - drop the connection
  3 - release the module
  4 - drop the packet and release the module
  5 - drop the connection and release the module

  Example:

  int
  filter(char* host, unsigned char* message, int* length)
  {
    int i;
    for (i = 1; i < *length; ++i) {
      if (message[i-1] == 'M') {
        if (message[i] == '1') {
          return 1; /* ignored */
        }
        if (message[i] == '2') {
          return 2; /* dropped */
        }
        if (message[i] == '3') {
          return 3; /* release */
        }
        if (message[i] == '4') {
          return 4; /* ignored + release */
        }
        if (message[i] == '5') {
          return 5; /* dropped + release */
        }
      }
    }
    return 0; /* allow to transfer */
  }

Modules have to be compiled with
.B -fPIC -shared
options.

.SH "SEE ALSO"

.BR afclient.conf (5),
.BR afserver (1),
.BR afserver.conf (5)
  
.SH BUGS

.B Afclient
is still under development. There are no known open bugs at the moment.

.SH "REPORTING BUGS"

Please report bugs to <jeremian [at] poczta.fm>

.SH AUTHOR

Jeremian <jeremian [at] poczta.fm>

.SH CONTRIBUTIONS

Alex Dyatlov <alex [at] gray-world.net>, Simon <scastro [at] entreelibre.com>, Ilia Perevezentsev <iliaper [at] mail.ru>, Marco Solari <marco.solari [at] koinesistemi.it>, and Joshua Judson Rosen <rozzin [at] geekspace.com>

.SH LICENSE

Active Port Forwarder is distributed under the terms of the GNU General Public License v2.0 and is copyright (C) 2003-2007 jeremian <jeremian [at] poczta.fm>. See the file COPYING for details.