tsocks - Library for intercepting outgoing network connections and redirecting them through a SOCKS

       Shaun Clowes (delius@progsoc.uts.edu.au)

tsocks can only proxy outgoing TCP connections

       tsocks does NOT work correctly with asynchronous sockets (though it does work with non blocking sockets).
       This  bug  would  be  very  difficult to fix and there appears to be no demand for it (I know of no major
       application that uses asynchronous sockets)

       tsocks is NOT fully RFC compliant in its implementation of version 5  of  SOCKS,  it  only  supports  the
       'username  and  password' or 'no authentication' authentication methods. The RFC specifies GSSAPI must be
       supported by any compliant implementation. I haven't done this, anyone want to help?

       tsocks can force the libc resolver to use TCP for name queries, if it does this it does it regardless  of
       whether  or  not  the DNS to be queried is local or not. This introduces overhead and should only be used
       when needed.

       tsocks uses ELF dynamic loader features to intercept dynamic function calls from programs in which it  is
       embedded.   As  a  result,  it  cannot  trace  the  actions  of  statically  linked  executables, non-ELF
       executables, or executables that make system calls directly with the system  call  trap  or  through  the
       syscall() routine.

       Copyright 2000 Shaun Clowes

       tsocks  and its documentation may be freely copied under the terms and conditions of version 2 of the GNU
       General Public License, as published by the Free Software Foundation  (Cambridge,  Massachusetts,  United
       States of America).

       This  documentation  is based on the documentation for logwrites, another shared library interceptor. One
       line of code  from  it  was  used  in  tsocks  and  a  lot  of  the  documentation  :)  logwrites  is  by
       adam@yggdrasil.com (Adam J. Richter) and can be had from ftp.yggdrasil.com pub/dist/pkg

Shaun Clowes                                                                                           TSOCKS(8)

tsocks is a library to allow transparent SOCKS proxying. It wraps the normal connect() function.  When  a
       connection  is  attempted,  it  consults  the  configuration file (which is defined at configure time but
       defaults to ~/.tsocks.conf and if that file cannot be accessed, to /etc/tsocks.conf)  and  determines  if
       the  IP  address specified is local. If it is not, the library redirects the connection to a SOCKS server
       specified in the configuration file. It then negotiates that connection with the SOCKS server and  passes
       the connection back to the calling program.

       tsocks  is  designed  for  use in machines which are firewalled from then internet. It avoids the need to
       recompile applications like lynx or telnet so they can use SOCKS to reach the internet. It  behaves  much
       like the SOCKSified TCP/IP stacks seen on other platforms.

   ARGUMENTS
       Most  arguments  to  tsocks  are  provided in the configuration file (the location of which is defined at
       configure time by the --with-conf=<file> argument but defaults to  /etc/tsocks.conf).  The  structure  of
       this file is documented in tsocks.conf(8)

       Some configuration options can be specified at run time using environment variables as follows:

       TSOCKS_CONF_FILE
              This  environment  variable  overrides the default location of the tsocks configuration file. This
              variable is not honored if the  program  tsocks  is  embedded  in  is  setuid.  In  addition  this
              environment  variable  can  be  compiled  out  of  tsocks  with  the --disable-envconf argument to
              configure at build time

       TSOCKS_DEBUG
              This environment variable sets the level of debug output that should be generated by tsocks (debug
              output is generated in the form of output to standard error). If this variable is not  present  by
              default  the  logging level is set to 0 which indicates that only error messages should be output.
              Setting it to higher values will cause tsocks to generate more  messages  describing  what  it  is
              doing.  If  set  to  -1 tsocks will output absolutely no error or debugging messages. This is only
              needed if tsocks output interferes with a program  it  is  embedded  in.  Message  output  can  be
              permanently  compiled out of tsocks by specifying the --disable-debug option to configure at build
              time

       TSOCKS_DEBUG_FILE
              This option can be used to redirect the tsocks output (which would normally be  sent  to  standard
              error) to a file. This variable is not honored if the program tsocks is embedded in is setuid. For
              programs where tsocks output interferes with normal operation this option is generally better than
              disabling messages (with TSOCKS_DEBUG = -1)

       TSOCKS_USERNAME
              This  environment  variable  can  be  used to specify the username to be used when version 5 SOCKS
              servers request username/password authentication. This overrides the default username that can  be
              specified in the configuration file using 'default_user', see tsocks.conf(8) for more information.
              This variable is ignored for version 4 SOCKS servers.

       TSOCKS_PASSWORD
              This  environment  variable  can  be  used to specify the password to be used when version 5 SOCKS
              servers request username/password authentication. This overrides the default password that can  be
              specified in the configuration file using 'default_pass', see tsocks.conf(8) for more information.
              This variable is ignored for version 4 SOCKS servers.

   DNSISSUEStsocks  will  normally not be able to send DNS queries through a SOCKS server since SOCKS V4 works on TCP
       and DNS normally uses UDP. Version 1.5 and up do however provide a method to force  DNS  lookups  to  use
       TCP,  which  then  makes them proxyable. This option can only enabled at compile time, please consult the
       INSTALL file for more information.

   ERRORStsocks will generate error  messages  and  print  them  to  stderr  when  there  are  problems  with  the
       configuration  file  or the SOCKS negotiation with the server if the TSOCKS_DEBUG environment variable is
       not set to -1 or and --disable-debug was not specified at  compile  time.  This  output  may  cause  some
       problems with programs that redirect standard error.

   CAVEATStsocks  will  not  in the above configuration be able to provide SOCKS proxying to setuid applications or
       applications that are not run from a shell. You can force all applications to LD_PRELOAD the  library  by
       placing  the  path to libtsocks in /etc/ld.so.preload. Please make sure you correctly enter the full path
       to the library in this file if you do this. If you get it wrong, you will be UNABLE TO DO  ANYTHING  with
       the  machine  and will have to boot it with a rescue disk and remove the file (or try the saveme program,
       see the INSTALL file for more info).  THIS IS A ***WARNING***,  please  be  careful.  Also  be  sure  the
       library is in the root filesystem as all hell will break loose if the directory it is in is not available
       at boot time.

       /etc/tsocks.conf - default tsocks configuration file

tsocks  -  Library  for  intercepting  outgoing  network connections and redirecting them through a SOCKS
       server.

tsocks.conf(5) tsocks(1)

       Set LD_PRELOAD to load the library then use applications as normal

       The syntax to force preload of the library for different shells is specified below:

       Bash, Ksh and Bourne shell -

       export LD_PRELOAD=/lib/libtsocks.so

       C Shell -

       setenv LD_PRELOAD=/lib/libtsocks.so

       This process can be automated (for Bash, Bourne and Korn shell users) for a single  command  or  for  all
       commands in a shell session by using the tsocks(1) script

       You  can  also  setup  tsocks  in  such  a  way  that  all  processes automatically use it, a very useful
       configuration. For more information on this configuration see the CAVEATS section of this manual page.