Messages

1

General Discussion / What are your favorite free resources for understanding how DNS works?

« on: January 04, 2024, 07:09:26 pm »

I have been curious about how DNS works.
My goal is to go deeper than "it resolves names to IP addresses".

That led me to wondering what resources may know of that have increased your understanding of how DNS works.

So, if you feel like doing so, post a link or short description of something! You might also share your favorite CLI tools for exploring the protocol.

Thank you!

I just learned about the command host which I found helpful for a brief summary of where a domain resolves to.
I also found "A Warm Introduction to DNS": https://powerdns.org/hello-dns/ a helpful technical deep-dive.

2

23.7 Legacy Series / Re: [SOLVED] help me answer the mystery unplugging LAN device drops WAN

« on: January 04, 2024, 06:37:14 pm »

I do need the ability to have LAN and other free interfaces offer connected clients an IP address via DHCP.

As a beginner, I was confused by configuring DHCP versus enabling DHCP service for an interface.

You can have as many statically configured interfaces as you like and of course you can run a DHCP server on all of them.

This highlights what I missed.

To restate in my own words:
In OPNsense, you may only have one interface configured as DHCP.
You may have any of the other interfaces configured to use a DHCPv4 or DHCPv6 server.

This distinction was new to me!

3

General Discussion / Re: No Internet connectivity with OPT3 interface

« on: December 30, 2023, 07:13:51 pm »

What am I missing here?

I'm curious what is meant by "No internet connectivity"

I recommend trying to simplify the problem. I prefer using a few command line tools as they give you precise answers to which part of the network connection may not be working.

From a client connected to the OPT3 interface, can the client 

• ping 8.8.8.8?
• ping duckduckgo.com?
• host duckduckgo.com?

4

23.7 Legacy Series / Re: help me answer the mystery unplugging LAN device drops WAN

« on: December 30, 2023, 06:45:06 pm »

You cannot have two interfaces with DHCP

Thanks for the insight Patrick!

I pondered this and realized how I had misconfigured LAN and AP to both use a DHCP server.
I then unchecked "Enable DHCP server on the LAN interface" in Services > DHCPv4 for LAN.

Then, unplugging the ethernet cable in igc0 did not cause clients connected to the AP interface by way of wifi to lose their WAN access.

Did or didn't you manually create a bridge interface?

I have not manually created a bridge interface.

Do LAN and AP use two separate IP networks or the same one?

LAN and AP are on the same IP network but different subnets.
LAN is 192.168.1.x.
AP is 192.168.30.x

Thanks for the reminder of all that happens when an interface drops.

5

23.7 Legacy Series / Re: help me answer the mystery unplugging LAN device drops WAN

« on: December 30, 2023, 03:34:40 pm »

What is the DHCP server for LAN and why?

oops, I posted incorrectly. I have LAN set to a static interface.
I would like to have 1 DHCP server on the local network.

Are LAN and AP bridged in OPNsense, possibly?

Great question. How can I disconfirm this or view the status in the interface?

6

23.7 Legacy Series / [SOLVED] help me answer the mystery unplugging LAN device drops WAN

« on: December 30, 2023, 01:27:21 pm »

howdy folks  .
pfsense convert here. I'm happy to begin using opnsense for my network.

I have a fun problem I would appreciate help debugging.

When I unplug the ethernet cable from a Linux client igc0 device (LAN), clients connected to the AP interface lose all upstream network access. They cannot reach the upstream router (opnsense).
I'm curious why this happens.

The  box is a Qotom J4105 that has 5 Intel I225-V ethernet ports. I have installed the latest opnsense with all patches.
I have stayed close to a default installation; some firewall and unbound configuration applied.
I am using IPv4 and have turned off IPv6 as far as I can tell.

I have 3 interfaces assigned to the first 3 ports:

• LAN on igc0 Static IPv4 192.168.1.1/24
• WAN on igc1 DHCP IPv4
• AP on igc2 Static IPv4 (a bridged wireless access point running OpenWrt)

If I leave the LAN ethernet cable plugged into my Linux client, the clients connected to the AP can reach opnsense and WAN.
When I unplug the  LAN ethernet cable only from the Linux clients, the clients connected to the AP cannot reach opnsense or WAN.

This issue seemed similar to https://forum.opnsense.org/index.php?topic=27299.150
. I tried spoofing WAN and LAN MAC addresses but that did not resolve the issue.

I've also verified the ISP router retains the default route when I unplug the client ethernet cable on LAN.

Now for questions!

• Is some kind of bridging behavior at work here?
• What configuration should I post to focus the troubleshooting?

Thank you for reading and any insight.

(edited for formatting and incorrect LAN details)