Netcat IP Spoofing

Question

I am connecting to a server

nc -v 192.168.0.1 1111

But I want to do IP spoofing because the server on 192.168.0.1 only accepting commands from 7.7.7.7. We are two friends, I am 192.168.1.1, and my friend is 192.168.0.1. My friend installed a daemon (on port 1111) and runs

ncat -u -c /bin/bash --allow 7.7.7.7 -l 1111

I know netcat's -s parameter, but I don't know how to use it. I tried

nc -v 192.168.0.1 1111 -s 7.7.7.7
7.7.7.7: inverse host lookup failed: Unknown server error : Connection timed out

How can I use netcat to connect with a spoofed IP address?

Answer 1

Netcat does not support IP-spoofing. Also, when there is one or more routers in between, the odds that IP-spoofing will be working is zero. When using 192.168.1.x and 192.168.0.y having a router in between is very likely.

Also 7.7.7.7 is a publicly assigned address. You cannot use it for your own.

If you want to experiment with other IP-addresses, use addresses from these ranges:

• 10.x.y.z
• 172.24.0.0 - 172.31.255.255
• 192.168.x.y

netcat needs to bind to an IP address that is available on your computer. You can check those by typing sudo ifconfig -a. Notice that all 127.x.y.z addresses are loopback addresses and only exist inside your own PC.

Answer 2

The netcat -s parameter is used to set the source address. This parameter is used if you have multiple interfaces, and multiple exit gateways that can be used. netcat manual

It seem to me that you are trying to set the source ip to an ip that is not routed back to you on your gateway.

The traffic flow would look something similar to this for the three-way handshake: (192.168.0.254 is your default gateway used to reach internet).

7.7.7.7 -> 192.168.0.1 (SYN)

192.168.0.1 -> 192.168.0.254 (SYN+ACK) # At this point, the packet will be routed through the gateway, destination is still 7.7.7.7

192.168.0.254(official internet ip) -> 7.7.7.7 (SYN+ACK)

7.7.7.7 -> 192.168.0.254(official internet ip) (RST) # Packet is disregarded by 7.7.7.7 is not familiar with this connection.

As you can see, you will be able to spoof the initial packet to the server, but you are unable to complete the three-way-handshake which is required to send any commands/data. The reason for this is because the response traffic will not be sent back to you, but to the real 7.7.7.7 ip.

A method to perform a successful spoofing attack is by man-in-the-middle, where you convince 192.168.0.1 that you are the gateway. When 192.168.0.1 send the SYN+ACK response towards 7.7.7.7, you will intercept the traffic and can act as 7.7.7.7.

Paper about ARP and attacks

Answer 3

'Connection' is not possible by spoofing. When his computer responds, it will be to the address that is not you. You have to send commands 'blind'.

To prove this, send a ping request (to your machine) to your friend's netcat session (while spoofing) and capture packets to see if you get anything.

** EDIT **

It IS possible to IP spoof with netcat! Just assign the spoofed IP to your local interface and set up a gateway:

eth0 IP: 192.168.1.1
IP to spoof: 7.7.7.7
Target IP: 5.5.5.5

ifconfig eth0 7.7.7.7
route add -net 7.7.7.0 eth0
nc -nvu -s 7.7.7.7 -g 192.168.1.1 5.5.5.5 1111

The problem is that many Internet routers block this type of spoofing.

Strict Source Routing

You can set up full-connections while spoofing, but you need to set up a gateway chain to do it:

eth0 IP: 192.168.1.10
Firewall IP: 192.168.1.1
IP to spoof: 7.7.7.7
Target IP: 5.5.5.5
IPs of Internet routers to Target (up to 8): n.n.n.[1-8]

ifconfig eth0 7.7.7.7
route add -net 7.7.7.0 eth0
nc -nvu -s 7.7.7.7 -g 192.168.1.10 192.168.1.10 1111
nc -nvu -s 7.7.7.7 -g 192.168.1.10 192.168.1.1 1111
nc -nvu -s 7.7.7.7 -g 192.168.1.10 -g 192.168.1.1 n.n.n.1 1111
...
nc -nvu -s 7.7.7.7 -g 192.168.1.10 -g 192.168.1.1 -g n.n.n.8 5.5.5.5 1111

Answer 4

Everything you should do is to write private IP address on the address bar on your own favourite internet browser and click enter. It usually is beneficial for you to utilize internet browser with maximum help for world wide web requirements (similar to Firefox) for the greatest end results. You're going to be taken up to precisely what is critically the computer software which drives your current networking unit. Below you may make corrections to configurations, set your account information, and set up your networking unit as you think fit.

As is also the way it is with any computer system setup, it usually is to your best benefit either to come up with a total data backup of the configuration settings before you decide to modify them or note down the defaults for each function that you choose to transform. A couple of inaccurate configuration settings when making your own computer network unit and you might eliminate your internet connection.

If anything truly does go awry when updating your network system piece of equipment via 192.168.1.1 ip, there's often a hardware reset control key on the backside of the piece of equipment that can bring back each of the controls to the manufacturer defaults.