#NETCAT REVERSE SHELL COMMAND CODE#

The server ICMP Agent sends ICMP packets to connect to the victim running a custom ICMP agent and sends it commands to execute.

The client ICMP agent listens for ICMP packets from a specific host and uses the data in the packet for command execution. The above discussion laid down little idea that ICMP communication can be used to contact between two devices using a custom agent running on victim and attacking devices. Hence, echo request-response communication is taking place between the network devices, but not over specific port(s). See the image below:ДЄs you can see, the packet does not contain source and destination port numbers like TCP and UDP header formats. Network device B (10.0.0.8) replies with a ping echo response with the same 48 bytes of data. Looking at the ping echo request and response, we can see that the ping echo request ICMP packet sent by network device A (10.0.0.7) contains 48 bytes of data. Images below show the PING echo request-response communication taking place between two network devices. When a device wants to test connectivity to another device, it uses the PING tool (ICMP communication) to send an ECHO REQUEST and waits for an ECHO RESPONSE. ICMP differs from the widely used TCP and UDP protocols because ICMP is not used for transferring data between network devices. ICMP stands for Internet Control Message Protocol it is used by network devicesвЂ™ query and error messages. Imagine a scenario in which communication to and from the server is protected and filtered by a firewall and does not allow TCP shell communication to take place on any listening port (both reverse and bind TCP connection).ДЇigure 3: Firewall blocks bind & reverse connectionД«ut many environments allow ping requests to be sent and received. One thing which is common between all these shells is that they all communicate over a TCP protocol. To name a few: Reverse TCP Meterpreter, C99 PHP web shell, JSP web shell, Netcat, etc. There are a number of popular shell files.

#NETCAT REVERSE SHELL COMMAND CODE#

The attacker then connects to the victim machineвЂ™s listener which then leads to code or command execution on the server. The attacking machine has a listener port on which it receives the connection, which by using, code or command execution is achieved.Д«ind shell is a type of shell in which the target machine opens up a communication port or a listener on the victim machine and waits for an incoming connection. A reverse shell is a type of shell in which the target machine communicates back to the attacking machine.

Netcat reverse shell command