1Tcpcrypt 2======== 3 4Tcpcrypt is a protocol that attempts to encrypt (almost) all of your network 5traffic. Unlike other security mechanisms, Tcpcrypt works out of the box: it 6requires no configuration, no changes to applications, and your network 7connections will continue to work even if the remote end does not support 8Tcpcrypt, in which case connections will gracefully fall back to standard 9clear-text TCP. 10 11Tcpcrypt supports Linux, Mac OS X, Windows, and FreeBSD. 12 13For more information, see [tcpcrypt.org](http://tcpcrypt.org). 14 15Installing tcpcrypt 16------------------- 17 18 git clone git://github.com/scslab/tcpcrypt.git 19 cd tcpcrypt 20 ./bootstrap.sh 21 ./configure 22 make 23 sudo ./launch_tcpcryptd.sh 24 25The launch script starts tcpcryptd and adds firewall rules to divert all TCP 26traffic on port 80 to tcpcryptd. When the script exits (on Ctrl-C or `kill`), 27it restores your firewall config to its former state -- *no permanent changes 28are made*. 29 30On Linux, you must first install libnfnetlink, libnetfilter_queue, and libcap. 31 32Optional: running `make install` will install `libtcpcrypt` and tcpcrypt 33headers, for building apps that use tcpcrypt's session ID. 34 35Try it out 36---------- 37 38Go to [http://tcpcrypt.org/test.php](http://tcpcrypt.org/test.php) with 39tcpcryptd running. If tcpcrypt is working, you'll be able to join the 40tcpcrypt Hall of Fame and your tcpcrypt session ID will be displayed at the 41bottom of the page. 42 43Now let's examine the packets going over the wire by starting tcpdump and then 44reloading the URL above. 45 46 sudo tcpdump -X -s0 host tcpcrypt.org 47 48Compare this tcpdump output, which appears encrypted (or at least unreadable), 49with the cleartext packets you would see without tcpcryptd running. 50 51Troubleshooting 52--------------- 53 54If it's not working, the most likely causes are the following. 55 56 * Your browser already had an open, non-tcpcrypted TCP connection to 57 tcpcrypt.org before you ran the launch script. Quit and reopen your 58 browser, wait 30 seconds, or use a different browser to retrieve the 59 tcpcrypt.org URL. 60 61 * There's a conflict with your existing firewall rules. See the 62 firewall setup section in the install guide for your platform. 63 64Visit [http://wiki.github.com/scslab/tcpcrypt/troubleshooting](http://wiki.github.com/scslab/tcpcrypt/troubleshooting) if you're still 65unable to make it work. 66 67 68More info 69--------- 70 71The `INSTALL-*` files have more detailed installation and firewall setup instructions. See [tcpcrypt.org](http://tcpcrypt.org) for general info, including the [protocol specification](http://tcpcrypt.org/docs.php) and the [tcpcrypt paper, "The case for ubiquitous transport-level encryption"](http://tcpcrypt.org/tcpcrypt.pdf), presented at USENIX Security 2010. 72 73The code repository lives at [http://github.com/scslab/tcpcrypt](http://github.com/scslab/tcpcrypt). 74