Adding a direct cable network connection

Rocky Linux Help & Support
1

I have a Rocky Linux 9.6 system which already has two ethernet connections, each with their own cable. I need to add a third connection (with it’s own cable) which will be a direct cable connection to one other system. I have been having a many problems getting this to work. I’ve searched around and don’t see any examples of this being done on modern Linux with nmcli. Can some one point me to instructions for this?

2

You might tell us about your hardware, and if you already added a third ethernet connection, how you accomplished that. In contrast, for example, some hardware (e.g. Dell PowerEdge) comes standard with four ethernet connections “out of the box”.

Tony

3

It’s a HP DL380 Gen9. It’s old but it has 4 ethernet connections out of the box.

4

Maybe nmtui will help!?

5

With a direct connection without using a switch, and assuming both network cards have been given an IP then it most likely will need a CAT5 crossover RJ45 cable. If you don’t have a crossover cable, then you will need to connect both computers to a switch/hub/router.

6

First, IMHO it helps to think: Machine does not have network – Network has machines

You want a subnet that has two machines. Static config should be sufficient.

These days NICs are at least 1Gbps and hence do support MDI-X. If these do (support MDI-X), then you can put regular cable there. (In times before MDI-X one had to get a crossover cable.)

Let say the subnet is 10.50.90.0/24 (or any other subnet that is not same as the other two existing subnets).
Then this machine could be 1 and the other 2, i.e. have addresses 10.50.90.1 and 10.50.90.2, respectively.

Surely the man nmcli-examples has example of creating Ethernet interface with address 10.50.90.1/24?

1 Like
7

Now that we understand that your hardware has four ethernet ports, can you be more specific about what is NOT working? Is this inability to SSH, PING, ROUTE, etc?

Tony