How to share a connection?

Question

User interface

Hello. There is a wire with an external device (wan), it comes to the office, then to the firewall, which this thread divides into eth1 and eth2. In the first interface there is a local office for the office, in the second there is a clean Internet. The evil uncle boss decided that we, the system administrators, did not need the Internet and turned off eth2. We sit and think, if the wire is cut in half, then there will be 2 grids of 10 Mbit each, including Lan, which is not enough for 15 office employees. How can we eat the fish and get the outside?) eth2 turn on pale - there is a notification for the boss's soap.

Answer 1

If the uncle boss decided that the system administrators (who, on duty, are required to use the Internet to read help, find useful information on habré / stackoverflow / wikipedia, the sites of the products themselves; to download updates and read release notes; and much more), I would quit this job. Let the uncle chief admin himself.
PS Quietly raise the proxy server on any of the workstations where there is an Internet, and walk through it. You can raise a few, and periodically change proxy settings so as not to create too much left traffic for a particular user, if this is tracked.

Answer 2

It is very incomprehensible how you are going to cut the first port into two, for any type of device it is incomprehensible =)
If you control the device to which the external Internet comes, then the question is clearly asked in vain. If you don’t control, then get control or install a second device over which you will have control and resolve the situation with the network and traffic on it.

Answer 3

For the count of such bosses :( Well, or drink beer :)