How to remote monitor a computer network traffic?
I'm assuming that what you're doing is related to ethical pen. testing. If you have no legitimate control over your target, you have 3 options
Haxoring your target: Attempt to gain access to the target machine by exploiting some vulnerabilities in the machine itself, or the operator of the machine.
Big Man in the Middle (Between your target and the servers to which he's connecting): Attempt to gain access to the network device used by your target. For example, find some vulnerabilities or default passwords in the routers or gateways your target uses.
Man in the Middle (Between your target and his local network gateway): Attempt to trick your target into sending his traffic through you. By far, the easiest way to achieve this is through ARP Spoofing. An easy-to-use tool is Cain and Abel.
(Cain and Abel)
You have three options:
- install wireshark or similar on the target
- monitor traffic through the network device
- add your own network device that is in a position to detect the target traffic
From your own comments, options 1 and 2 are ruled out already. It may be, though, that you are precluded from the final option by your contract.
In my opinion you would be best served by requesting a monitoring tool from the company that provides the network or owns the contract. If this meets the needs of the company then you may get it agreed.
This is easy to do provided you have administrative access to your network devices, and they support port mirroring . What you do is mirror the port of the end point you want to monitor, and then use a sniffing tool like wireshark, tcpdump, or snoop to record the traffic.