icmpsh's Introduction

icmpsh - simple reverse ICMP shell

icmpsh is a simple reverse ICMP shell with a win32 slave and a POSIX compatible master in C or Perl.

Running the Master

The master is straight forward to use. There are no extra libraries required for the C version. The Perl master however has the following dependencies:

IO::Socket
NetPacket::IP
NetPacket::ICMP

When running the master, don't forget to disable ICMP replies by the OS:

sysctl -w net.ipv4.icmp_echo_ignore_all=1

If you miss doing that, you will receive data from the slave, but the slave is unlikely to retrieve any commands sent from the master.

Running the Slave

The slave comes with a few command line options as outlined below:

-t host            host ip address to send ping requests to. This option is mandatory!

-r                 send a single test icmp request containing the string "Test1234" and then quit. 
		   This is for testing the connection.

-d milliseconds    delay between requests in milliseconds 

-o milliseconds    timeout of responses in milliseconds. If a response has not received in time, 
		   the slave will increase a counter of blanks. If that counter reaches a limit, the slave will quit.
                   The counter is set back to 0 if a response was received.

-b num             limit of blanks (unanswered icmp requests before quitting

-s bytes           maximal data buffer size in bytes

In order to improve the speed, lower the delay (-d) between requests or increase the size (-s) of the data buffer.

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