Linking a LAN to a USB tethered laptop

B

balanga

I have no idea if this is possible but someone here will know the answer.

I have a small LAN where all the systems are wired up to a 4G router. I also have an isolated laptop which accesses the Internet by USB tether to a phone.

How would I go about accessing my LAN from my laptop. if that is possible?
 
If both your Lan-Router and the phone have real vaild internet adresses and does not exist behind so called NAT-firewalls that hide the Internet adress of the computer from external view, then its possible to setup Routing from the LAN to the Laptop.
Most likely both your computer on the Lan and the Laptop has received a NAT address. ( eg 192.168.0.X ) wich are used on local Lans
the Internet does not propagate adresses in the range 192.168.0.1 to 192.168.255.255 . These adresses blocked from traverisng the Internetwork. Other blocked segments are 10.0.0.1 through 10.255.255.254 , and 172.16.0.1 through 172.31.255.254 .

see https://datatracker.ietf.org/doc/html/rfc1918

A often exsisting feature of a 4G router is that it may allow you to redirect WEB traffic HTTP / HTTPS from port 80/443 on the router to the same ports on a computer connected to the Routers inside LAN. which would allow traffice to a WEB server on that said computer.
possibly the 4G Router allows this funktionality for other protocols as well.
DOING THIS OBVIOUSLY WILL HAVE SECURITY RISKS: as you allow internet traffic to the internal computer.
**** You will be requiered to setup a firewall on the internal computer ****
Then you laptop will be able to SURF to your internal Computer using the IP adress of the ROUTER.
 
there is a good probability that the 4g provider (both router and phone) will not give you a routable address.
you will most likely need to rent a vps and connect both laptop and lan to a vpn on the vps. then talk via vpn
 
I have a similar setup. Laptop connected to internet over wifi <-> Mobile Phone hotspot (192.168.23.0/24), the same laptop connected to a local router (192.168.1.0/24) over ethernet or wifi (built-in and external wifi dongle) at the same time.

I can access all devices on the 192.168.1.0/24 subnet (over NFS, or ssh(1), for example) and surf the internet simultaneously. The default gateway is set to 192.168.23.1 in this case.

This shouldn't be any different on your setup. If over wifi, configure /etc/wpa_supplicant.conf accordingly, if ethernet, and the router is running a DHCP server, plug in the ethernet cable to get a lease. If the router has no DHCP server, assigne an IP to the network interface from the LAN subnet address pool.

If you have problems accessing the internet, check the default gateway ( netstat -rn), eventually change the default gateway (route(8)).
 
All you need is set up NAT on the computer which is tethered. And then set that computer as default gateway on the other computers.
 
I have a no-name USB->ethernet adapter between one of my laptops and my router... no stinkin' NAT needed, the laptop is on my LAN directly, and Internet access is not a problem, either.
😏

If OP wants to access the LAN via the phone tether - just let the phone be a client on the router. Phone gets the 192.168.1.x address from the router, and by extension, so will the laptop.
 
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