simple vpn program with tun/tap driver

Author: ivanria

simple-tun/Makefile

@@ -0,0 +1,30 @@
+export PROG	:= tunnel
+SRC_DIR		:= ./src
+export CC	:= gcc
+export CFLAGS	:= -Werror -Wall -Wextra -DDEBUG -g
+
+.PHONY: all
+all:
+	$(MAKE) -C $(SRC_DIR) all
+
+.PHONY: install
+install:
+	$(MAKE) -C $(SRC_DIR) install
+
+.PHONY: clean
+clean:
+	$(MAKE) -C $(SRC_DIR) clean
+
+.PHONY: cleanall
+cleanall:
+	$(MAKE) -C $(SRC_DIR) cleanall
+
+.PHONY: print_vars
+print_vars:
+	@echo "===print_vars==="
+	@echo "PROG		= $(PROG)"
+	@echo "SRC_DIR		= $(SRC_DIR)"
+	@echo "CFLAGS		= $(CFLAGS)"
+	@echo "LDFLAGS		= $(LDFLAGS)"
+	$(MAKE) -C $(SRC_DIR) print_vars
+

simple-tun/README

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+simple vpn program, it works with tun/tap linux kernel driver
+may be this is vpn tunnel over icmp messages

simple-tun/example/a.out

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+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <string.h>
+
+int main()
+{
+
+char str[100];
+int listen_fd, comm_fd;
+
+struct sockaddr_in servaddr;
+
+listen_fd = socket(AF_INET, SOCK_STREAM, 0);
+
+bzero( &servaddr, sizeof(servaddr));
+
+servaddr.sin_family = AF_INET;
+servaddr.sin_addr.s_addr = htons(INADDR_ANY);
+servaddr.sin_port = htons(12345);
+
+bind(listen_fd, (struct sockaddr *) &servaddr, sizeof(servaddr));
+
+listen(listen_fd, 10);
+
+comm_fd = accept(listen_fd, (struct sockaddr*) NULL, NULL);
+
+while(1)
+{
+
+bzero( str, 100);
+
+read(comm_fd,str,100);
+
+printf("Echoing back - %s",str);
+
+write(comm_fd, str, strlen(str)+1);
+
+}
+}

simple-tun/example/echoserver

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+Send suggestions, bug reports, criticisms to Davide Brini <dave_br@gmx.com>

simple-tun/example/echoserver.c

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+0.01
+----
+
+01/09/2009 Changed the way packets are sent over TCP, now all kinds of frames/packets/protocols are supported.
+27/03/2010 Some clean up and reformatting.

simple-tun/example/simpletun.tar.bz2

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+simpletun, a (too) simple tunnelling program.
+
+-------
+
+To compile the program, just do
+
+$ gcc simpletun.c -o simpletun
+
+If you have GNU make, you can also exploit implicit targets and do
+
+$ make simpletun
+
+-------
+
+Usage:
+simpletun -i <ifacename> [-s|-c <serverIP>] [-p <port>] [-u|-a] [-d]
+simpletun -h
+
+-i <ifacename>: Name of interface to use (mandatory)
+-s|-c <serverIP>: run in server mode (-s), or specify server address (-c <serverIP>) (mandatory)
+-p <port>: port to listen on (if run in server mode) or to connect to (in client mode), default 55555
+-u|-a: use TUN (-u, default) or TAP (-a)
+-d: outputs debug information while running
+-h: prints this help text
+
+-------
+
+Refer to http://backreference.org/2010/03/26/tuntap-interface-tutorial/ for 
+more information on tun/tap interfaces in Linux in general, and on this 
+program in particular.
+The program must be run at one end as a server, and as client at the other 
+end. The tun/tap interface must already exist, be up and configured with an IP 
+address, and owned by the user who runs simpletun. That user must also have
+read/write permission on /dev/net/tun. (Alternatively, you can run the
+program as root, and configure the transient interfaces manually before
+starting to exchange packets. This is not recommended)
+
+Use is straightforward. On one end just run
+
+[server]$ ./simpletun -i tun13 -s
+
+at the other end run
+
+[client]$ ./simpletun -i tun0 -c 10.2.3.4
+
+where 10.2.3.4 is the remote server's IP address, and tun13 and tun0 must be 
+replaced with the names of the actual tun interfaces used on the computers.
+By default it assumes a tun device is being used (use -u to be explicit), and
+-a can be used to tell the program that the interface is tap. 
+By default it uses TCP port 55555, but you can change that by using -p (the 
+value you use must match on the client and the server, of course). Use -d to 
+add some debug information. Press ctrl-c on either side to exit (the other end
+will exit too).
+
+The program is very limited, so expect to be disappointed.