Solved How To Share Your Laptop's Wireless Internet Connection Over Ethernet

[bsd_user_1234]

INTRO

Ladies, gentlemen, and cyber friends,
recently I've had to install FreeBSD on a PC that did not have a wireless NIC,
and the router was so inconveniently placed that connecting directly via cable was out of the question.
So, I decided to connect to the Wi-Fi through my FreeBSD laptop and then share its internet connection with the PC over the ethernet port.
This is a guide on how you can configure such a setup with two FreeBSD devices.

STEP 1: PREPARE THE LAPTOP

First, enable IP forwarding (you may need root privilages):

sysctl net.inet.ip.forwarding=1

Then, assign an IP address to your ethernet NIC (you may need root privilages);
In my case, the LAN connected to the router had the standard IP: 192.168.100.0/24
So, I decided to assign the ethernet interface (re0) to another LAN, with IP: 192.168.101.1/24

ifconfig re0 192.168.101.1/24

The next step is to prepare a firewall rule that will perform NAT; We will be using pf.
Perhaps now is a good time to mention that my wireless interface is called wlan0.
So, I placed the following config in /etc/pf.conf:

ext_if = "wlan0"
int_if = "re0"
set skip on lo
nat on $ext_if from $int_if:network to any -> ($ext_if)
pass all

Finally, enable the firewall (you may need root privilages):

service pf onestart

I used onestart because I didn't enable the service. If you did, then 'start' should be used instead.

STEP 2: PREPARE THE PC

First, assign an address on the same local network for the ethernet interface, as the one on the laptop;
In this case, my PC's interface was called rge0 (you may need root privilages):

ifconfig rge0 192.168.101.2/24

Next, we will want to set the laptop as the default gateway (you may need root privilages):

route add default 192.168.101.1

Finally, update the DNS resolver; I like to use 8.8.8.8, because it's easy to remember (you may need root privilages):
Inside /etc/resolv.conf place:

nameserver 8.8.8.8

VERIFY THE CONNECTION

ping freebsd.org

And that would be all!

If this doesn't work, try:

ping 8.8.8.8

If this doesn't work, try:

ping 192.168.101.1

If the first one failed, it could be a problem with the DNS resolver.
If the second one failed, it could be a problem with the pf config.
If the third one failed, then it could be a problem with the interface addresses,
or it could be a faulty cable.