dns2tcpc(1)

Usage

dns2tcpc [-h] [-c] [-z domain zone] [-d debug_level] [-r resource] [-k key] [-f config_file] [-e command] [-T request type] [-l local_port] [server]

Overview

dns2tcpc is a network tool used to encapsulate TCP communications in DNS. When connections are received on a specific port all TCP traffic is sent to the remote dns2tcpd server and forwarded to a specific host and port. Multiple connections are supported.

dns2tcpc was written for demonstration purposes.

Options

-h: Help Menu

-c: Enable DNS compression. When used, be sure that all relay and DNS server support compression and really use it.

`-z domain zone`	Use this domain as endpoint.
`-d debug level`	Change debug level. Levels available are 1, 2 or 3.

-r resource: Remote resource to access.

-k key: Pre shared key used for authentication (identification).

`-f config file`	Configuration file to use.
`-T request type`	Request type to use. Actually only KEY and TXT requests are supported.

-e command: Command to execute, I/O are redirected in the tunnel.

-l local_port: Local port accepting incoming connections (or - for stdin on UNIX systems).

-t connection timeout: Maximum DNS server's answer delay in seconds. A valid delay is between 1 and 240 seconds. Default is 3.

server: DNS server to use. The first entry in resolv.conf file will be chosen if the server is not specified.

Configuration files

By default ${HOME}/.dns2tcprc is used if no configuration file is specified. Here is an example :

domain = dns2tcp.hsc.fr: resource = ssltunnel local_port = 4430 enable_compression = 0 debug_level = 1 key = mykey # DNS to use server = ns.hsc.fr

Examples

dns2tcpc -k mykey -z dns2tcp.hsc.fr mydns

: Ask the dns2tcp server to list available resources.

ssh -o 'ProxyCommand dns2tcpc -r ssh -l - -z dns2tcp.hsc.fr -k mykey mydns' myserver

: Use dns2tcp as a proxy command with ssh. We try to connect to the ssh resource with the key 'mykey' and the DNS mydns.

dns2tcpc -r socat-resource -e '/bin/bash -i' -k mykey -z dns2tcp.hsc.fr mydns

: Use dns2tcp as a reverse shell, the remote shell will appear on the socat-resource.

dns2tcpc -d 1 -f /dev/null -r ssl-tunnel -l 2000 -k mykey -T KEY -z dns2tcp.hsc.fr mydns

: Do not use the default configuration file, bind local port 2000 and forward all the traffic on the remote ssl-tunnel resource, use the first debug level. Use KEY type DNS requests.

Releases

9 releases since Debian 5.0 (Lenny); the text changed 2 times.

-e since Debian 6.0 (Squeeze); -k since Debian 6.0 (Squeeze).