一个vpn程序-dsptunnel

（客户端程序仅支持linux桌面系统）
IP over audio tunnel http://d00m.org/~someone/dsptunnel/

All you need are two computers with sound cards.
Connect the line-out of your first machine with the line-in of your second
machine and the line-out of your second machine with the line-in of the first.
Set your levels so you get a loud and clear signal on both ends.
Unity gain is best, so both playback and recording should be set to 0db.
Also, you'll need a stereo link, otherwise it won't work since this baby uses
differential signaling, if you know what I'm talking about.

Now you need to create the TUNnel devices on both machines.
As root on both machines:
# ip tuntap add dev tun0 mode tun user  group 
# ifconfig tun0 up

As root on machine 1:
# ifconfig tun0 10.0.0.1
# ifconfig tun0 pointopoint 10.0.0.2

As root on machine 2:
# ifconfig tun0 10.0.0.2
# ifconfig tun0 pointopoint 10.0.0.1

Don't forget to put in your user name and group so dsptunnel can access the
tunnel device without running as root (which would be a bad thing).
Feel free to replace the IPs with addresses of your choice (yay, FREEDOM).

Now simply run dsptunnel. If you don't have OSS run it using an OSS wrapper
like aoss or padsp. Now ping the other machine. Now set up routing and
enjoy your new slow Internet. And you can even listen to the bits.

If you have a really good sound card that supports 96khz sample rate you can
start dsptunnel with "-s 96000" to make use of it.
If you get trasmission errors you can increase the bit length using the -b
option. -t sets the name of the TUN device. -d sets the name of the dsp device.

This software is licensed under the GNU GPL V3. See LICENSE for details.
Send bugreports and questions to someone@d00m.org.

from https://github.com/50m30n3/dsptunnel 

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dsptunnel

dsptunnel is an IP over audio tunnel.
It allows you to create full duplex point to point tunnels over two stereo links using the kernels TUN/TAP driver.
Outgoing packets are modulated and send over the sound card, incoming packets are demodulated and fed to the TUN/TAP driver.
Data is send using differential signalling for simple clock recovery.
A checksum is appended to every packet to verify data integrity.
With a sound card supporting 48khz sampling rate you can transfer up to 3 kb/sec.


Source Download: dsptunnel.tar.gz



from http://d00m.org/~someone/dsptunnel/