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ds
sdt
sods
README.md

README.md

WHAT IS IT?

sods is a socket over dns server that uses the DNS to tunnel data. sods includes a small, portable client (sdt) and ds, a utility to scan for DNS servers that support recursion.

The protocol is interoperable with OzymanDNS (http://lmgtfy.com/?q=OzymanDNS).

WHAT DO I NEED TO BUILD IT?

Not much. OpenSSL is optional, if your OS doesn't support arc4random().

sods has been built on Ubuntu Linux, Maemo, OpenWRT, Mac OS X and Solaris.

HOW DO I BUILD IT?

Server

cd sods
./configure
# adjust the Makefile
make

Client

cd sdt
./configure
# adjust the Makefile
make

HOW DO I RUN IT?

# In the sods directory
sudo ./sods -vvvv -d /tmp -L 127.0.0.1:22 a.example.com # if you have an SSH server on localhost

# In the sdt directory
ssh -o ProxyCommand="./sdt -r 127.0.0.1 sshdns.a.example.com" 127.0.0.100

# As a TCP proxy
./sdt p 23233 -r 127.0.0.1 sshdns.a.example.com
ssh -p 23233 localhost # for OpenSSH

The sods client works best with GNU screen installed on your shell server (see the scripts directory for an example of a script to reconnect if the connection is dropped).

WHY WOULD I WANT TO USE IT?

sods is tiny, easily ported and fast. Well, sort of fast, for a tunnel going over DNS. Which means not really very fast.

sods has a few tricks to get around network limitations.

Some ways to use sods:

  • use of gated internet access that allow DNS queries, like those found in airports, coffee shops, restaurants and hotels, when you just need quick SSH access

  • to bypass firewall port or proxy filtering and snooping

  • penetration testing: bypass strict access controls on outgoing connections on secure networks

  • have fun with anyone doing traffic analysis on your network usage

FEATURES

  • use TXT, CNAME or NULL records to encapsulate data

  • supports multiple forwarded sessions (use multiple "-L" option)

  • round robin packets between name servers

  • bounce connections off of public recursive name servers (-r random)

  • dynamic backoff/throttling of client

  • client can use be used as a pipe (for OpenSSH) or as a TCP proxy (for other ssh clients)

TODO

  • remove hardcoded options and use define, e.g., nobody/nogroup

  • multiplex connections to the TCP proxy

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