Merge branch 'master' of github.com:msantos/sods

README

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+
+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 8.
+
+
+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
+
+* re-write the sods server in Erlang, using the native SSH
+support. Reliable, fault tolerant DNS and ssh server for an unreliable
+protocol!!
+
+* write an Erlang client
+
+* multiplex connections to the TCP proxy
+
+* allow the client to specify a host/port
+
+For example, if the client requests "mysshserver.com.sshdns.s.example.com",
+the request would cause the sods server to open a port to
+"mysshserver.com" on port 22. To specify a port, the client could
+embed the port, maybe: mysshserver.com-2222.sshdns.s.example.com

ds/Makefile

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+CC=gcc
+RM=rm
+
+#LIB=/usr/lib/libresolv.a
+LIB=-lresolv
+
+all:
+	$(CC) -g -Wall -o ds ds.c iprange.c $(LIB)
+
+clean:
+	-@$(RM) ds *.o