ptunnel(8)						       Yellow Lemon Software							ptunnel(8)

NAME

       ptunnel - tunnel TCP connections over ICMP echo request/reply packets.

SYNOPSIS

       ptunnel	-p  proxy_address -lp listen_port -da destination_address -dp dest_port [-c network_device] [-v verbosity] [-f file] [-udp] [-sys-
       log]

       ptunnel [-c network_device] [-v verbosity] [-f file] [-udp] [-syslog] [-daemon file]

       ptunnel [-u] [-x password] [-setuid user] [-setgid group] [-chroot dir] [-setcon context]

       ptunnel -h

DESCRIPTION

       ptunnel is an application that allows you to reliably tunnel TCP connections to a remote host using ICMP echo request  and  reply  packets,
       commonly  known	as ping requests and replies. At first glance, this might seem like a rather useless thing to do, but it can actually come
       in handy in some cases. The following example illustrates the main motivation in creating ptunnel:

       Setting: You're on the go, and stumble across an open wireless network. The network gives you an IP address, but won't let you send TCP	or
       UDP  packets  out  to  the rest of the internet, for instance to check your mail. What to do? By chance, you discover that the network will
       allow you to ping any computer on the rest of the internet. With ptunnel, you can utilize this feature to check	your  mail,  or  do  other
       things that require TCP.

OPTIONS

       Client options:

       -p proxy_address
	      Specify the host on which the proxy is running.

       -lp listen_port
	      Specifies the port on which the client will listen for incoming TCP connections.

       -da destination_addr
	      Specifies  the address to which you want your packets tunneled after reaching the proxy when in client mode, or restricts the desti-
	      nation packets can be forwarded to when in server mode.

       -dp destination_port
	      Specifies/restrict the port that the proxy should tunnel the TCP connection to.

       Shared options:

       -c network_device
	      Specify the network interface to capture packets from. Note that packet capturing isn't always necessary, but you should try this if
	      you experience problems with ptunnel.

       -v verbosity
	      Controls the verbosity level. -1 is no output, 0 shows errors only, 1 shows info messages, 2 gives more output, 3 provides even more
	      output, level 4 displays debug info and level 5 displays absolutely everything, including the nasty details of sends and receives.

       -udp   Enables tunneling over UDP port 53 (DNS) instead of using ICMP. This will only work if your proxy can  accept  incoming  traffic	on
	      port 53, and the client is able to send data to the proxy on port 53. Note that this option does not wrap ptunnel's data in DNS-com-
	      pliant packets. This option must be given on both the proxy and client side for things to work correctly.

       -syslog (Not available on Windows.)
	      Changes logging to use the built-in syslog fascility.

       -daemon file (Not available on Windows.)
	      Run in background, writing PID in file.

       -u     Attempts to run ptunnel without privileges. This doesn't usually work! On UNIX systems please consider  using  the  following  three
	      options instead:

       -setuid user (Not available on Windows.)
	      When started in privileged mode, drop down to user's rights as soon as possible.

       -setgid group (Not available on Windows.)
	      When started in privileged mode, drop down to group's rights as soon as possible.

       -chroot dir (Not available on Windows.)
	      When started in privileged mode, restrict file access to the specified directory.

       -setcon context (Not available on Windows.)
	      Set  SELinux  context when all there is left to do are network I/O operations.  In order to be able to combine with -chroot you will
	      have to `mount --bind /proc /chrootdir/proc`

       -x password
	      Specifies a password or passphrase to use. This will allow you to protect the proxy from use by others who don't know the  password.
	      It needs to be specified on both proxy and client.

       -f file
	      Specifies a log file. If you specify -syslog, syslog is always used instead.

       -h     Displays brief usage information.

EXAMPLES

       The  following  assumes	that ptunnel is run as root, both on the proxy and client. To tunnel ssh connections from the client machine via a
       proxy running on proxy.pingtunnel.com to the computer login.domain.com, the following command line would be used:

       ptunnel -p proxy.pingtunnel.com -lp 8000 -da login.domain.com -dp 22

       An ssh connection to login.domain.com can now be established as follows:

       ssh -p 8000 localhost

       If ssh complains about potential man-in-the-middle attacks, simply remove the offending key from the known_hosts file. The warning/error is
       expected  if you have previously ssh'd to your local computer (i.e., ssh localhost), or you have used ptunnel to forward ssh connections to
       different hosts.

       Of course, for all of this to work, you need to start the proxy on your proxy-computer (proxy.pingtunnel.com). Doing this is very simple:

       ptunnel

       If you find that the proxy isn't working, you will need to enable packet capturing on the main network device.  Currently  this	device	is
       assumed	to  be	an  ethernet-device  (i.e.,  ethernet or wireless). Packet capturing is enabled by giving the -c switch, and supplying the
       device name to capture packets on (for instance eth0 or en1). The same goes for the client. On Mac OS X, packet capturing  must	always	be
       enabled (both for proxy and client), as resent packets won't be received otherwise.

       To  protect  yourself from others using your proxy, you can protect access to it with a password using the <tt>-x</tt> switch. The password
       is never sent in the clear, but keep in mind that it may be visible from tools like top or ps, which can display the command line  used	to
       start an application.

EXIT STATUS

       ptunnel does not exit until forced to do so by an interrupt (Ctrl-C) or if it crashes.

BUGS

       ptunnel currently does not handle packet capturing on network interfaces other than ethernet or wireless correctly.

AUTHORS

       Daniel Stoedle (daniels@cs.uit.no)

       Mike Miller (mike@mikeage.net)

       Sebastien Raveau (sebastien.raveau@epita.fr)

LICENSE

       ptunnel is licensed under the BSD License.

AVAILABILITY

       The ptunnel homepage is currently located here:
	      http://www.cs.uit.no/~daniels/PingTunnel/

       The freshmeat project page is located here:
	      http://freshmeat.net/projects/ptunnel/

       Please take the time to rate ptunnel if you find it useful. Thanks!

Version 0.71							   June 22, 2009							ptunnel(8)