Provided by: tnat64_0.05-1_i386
tnat64 - Library for intercepting outgoing network connections and
redirecting them through the NAT64.
Set LD_PRELOAD to load the library then use applications as normal
The syntax to force preload of the library for different shells is
Bash, Ksh and Bourne shell -
C Shell -
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 tnat64(1) script
You can also setup tnat64 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.
tnat64 is a library to allow IPv4-only application to access IPv4 hosts
on IPv6-only systems by using NAT64. 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
/etc/tnat64.conf) and determines if the IP address specified is local.
If it is not, the library redirects the connection to an IPv6 address
inside the NAT64 prefix that is specified in the configuration file.
The redirection is performed only if the destination host is
unreachable (when there's no route to host). Also, after the first
successful redirection all the following connection attempts are
redirected immediately without even trying to connect to the host via
IPv4. When the destination host cannot be reached via IPv6, the
redirection is disabled.
tnat64 avoids the need to recompile applications so they can use reach
hosts even if they do not support IPv6 and there's no IPv4
tnat64 is heavily based on the source code of tsocks, a library that
intercepts outgoing TCP connections and redirects them though SOCKS
proxy. Many thanks for tsocks author, Shaun Clowes!
Most arguments to tnat64 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/tnat64.conf). The structure
of this file is documented in tnat64.conf(8)
Some configuration options can be specified at run time using
environment variables as follows:
This environment variable overrides the default location of the
tnat64 configuration file. This variable is not honored if the
program tnat64 is embedded in is setuid. In addition this
environment variable can be compiled out of tnat64 with the
--disable-envconf argument to configure at build time
This environment variable sets the level of debug output that
should be generated by tnat64 (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 tnat64 to generate more messages describing
what it is doing. If set to -1 tnat64 will output absolutely no
error or debugging messages. This is only needed if tnat64
output interferes with a program it is embedded in. Message
output can be permanently compiled out of tnat64 by specifying
the --disable-debug option to configure at build time
This option can be used to redirect the tnat64 output (which
would normally be sent to standard error) to a file. This
variable is not honored if the program tnat64 is embedded in is
setuid. For programs where tnat64 output interferes with normal
operation this option is generally better than disabling
messages (with TNAT64_DEBUG = -1)
tnat64 will generate error messages and print them to stderr when there
are problems with the configuration file if the TNAT64_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.
tnat64 will not in the above configuration be able to provide 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 libtnat64 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.
tnat64 can only proxy outgoing TCP connections
tnat64 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)
tnat64 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.
/etc/tnat64.conf - default tnat64 configuration file
Andrew O. Shadura (firstname.lastname@example.org), Shaun Clowes
Copyright 2011 Andrew O. Shadura
Original tsocks manual page, copyright 2000 Shaun Clowes
tnat64 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 heavily based on the documentation for tsocks,
transparent SOCKSification library, whose documentation itself 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 email@example.com (Adam J. Richter)
and can be had from ftp.yggdrasil.com pub/dist/pkg