WiFi SSIDs on different VLANs

Taking a different direction here and trying out a more HowTo style post. I thought I’d do a quick write-up covering WiFi SSIDs on multiple VLANs, something that might be useful in a home setup, separating SSIDs better from one another. While I usually prefer the CLI, a lot of the devices mentioned here only (or mainly) use a web GUI for configuration management, so this posting will include a lot more screenshots than my usual postings. This posting won’t contain anything exciting for people who run and support networks professionally (mostly just a “so what options are available on SOHO hardware?”), and may even be overly simple and assume settings you wouldn’t do in a professional setup. But it is useful for homelab enthusiasts looking to build a more complex setup than “everything on the same VLAN/network” or trying to figure out “how do I use VLANs, give me an example”.

Ubiquiti and Netgear have some reasonable priced network gear that I’ve written about in the past that behave decent in home networks. For out little setup today we will have a WiFi access point with multiple SSIDs, two switches, and a firewall/router. We will be focusing on the configuration of the WiFi Access Point (UniFi AP) , the two Netgear switches (GS105Ev2 / GS108Ev3) and the Ubiquiti Router (Edgerouter X).

Our goal is to have two SSIDs on the access point, one for the “normal” devices (VLAN 1), and one for separate devices (VLAN 178). Since the router to VLAN 178 is on a different switch than the access point we also need to trunk both VLANs across the network. Another way of looking at it, is that we are expanding Subnet/VLAN 178 into our network (but limiting it to the WiFi Access points). 178 doesn’t hold any special meaning, you can use any VLAN number you want, just chose 178 because the subnet in this test setup was

Here is a diagram of our test setup:

VLAN 1: The management and main client VLAN
VLAN 178: Subnet 178, 2nd WiFi network

Netgear 1

Port 1: Connection to Netgear 2
Port 5: Access Point

Netgear 2

Port 1: Connection to Netgear 1
Port 8: Edgerouter


eth0: Connection to Subnet 178
eth1: Connection to Netgear 2


Wireless Configuration

In the UniFi controller go to Settings->Wireless Networks either create a new network or edit an existing one. If you go into the advanced options area, you will find the VLAN setting for that SSID. Activating the option and setting a value means the access point will tag all packets from that SSID to the specified VLAN number.

In the network overview below we see that packets from one network are tagged with VLAN 178, and packets from the other network are untagged (the switch configuration will take care of deciding which VLAN untagged packets are part of).


Netgear Configuration

The Netgear devices only have a VLAN 1 defined by default, so the first step will be to add VLAN 178 to both of them. Enable Advanced 802.1q (VLAN->802.1Q->Advanced->VLAN Configuration), enter the VLAN ID 178 in the box and click on “Add” at the top.

Now let’s move on to the VLAN Membership configuration. To switch settings, just click on the port and it will switch from tagged->untagged->none.

Netgear 1 device

For VLAN 1 we want port 1 to be (T)agged since it is the trunk to the next switch, and all other ports (U)ntagged since they will be dealing with untagged VLAN 1 traffic. The PVID will also be set to 1 for all ports.

For VLAN 178 we want port 1 to be (T)agged since it is the trunk to the next switch, port 5 (T)agged since it is the connection to the access point, and all other ports “none” since none of those ports are part of VLAN 178.



VLAN overview after changing all the settings:


For this scenario it is sane to leave the Port PVID configuration to PVID 1 on all ports. You could change a port to 178 if you are expecting untagged traffic on that port that needs to be in VLAN 178.

Netgear 2 device

Similar configuration as the first switch so I’ll skip the screenshots. Port 1 is the connection to the Netgear 1 device, port 8 is connected to the Edgerouter.

    • all ports PVID 1
    • VLAN 1 Tagged port 1 and 8, all other ports untagged
    • VLAN 178 Tagged port 1 and 8, all other ports none


Edgerouter Configuration:

Make sure the interface switch0 spans all ports you want to use VLANs on. Add the two VLANs 1 and 178. They should show up in the list as switch0.1 and switch0.178, and you can apply firewall rules to these interfaces to restrict traffic if you are doing any routing between the two networks.
We will want to tag everything from Subnet 178 as VLAN 178 on the interface connected to that network (eth0 in our setup), and allow VLAN 178 on the outgoing interface (eth1 in our setup). The Edgerouter doesn’t need us to specifically allow VLANs already set by the PVID, only additional VLANs need to be specified in the vid field.


Where to go from here?

You could put servers or virtual machines in their own subnet/VLAN and then use a firewall to restrict access between the different networks.

Adding more Access Points is straightforward, UniFi automatically applies the wireless configuration to all Access Points it manages, so all you need to do is take care of the switch port configuration.

A short list of cheap but useful network devices to have handy.

Here is a snort list of useful, off the shelf, network devices that sell for around $50. Not necessarily stuff that you would want use long-term in production, but more for the one-off projects or for troubleshooting. 

First off is a 5-Port Gigabit switch from Netgear (the GS105Ev2).
It is interesting because it supports port mirroring and only costs about $35. That’s a really good price. It obviously isn’t going to replace a real network tap and you will lose traffic if the upstream plus downstream you are copying are together more than 1Gbit of traffic (but that’s a problem you always have when mirroring ports 1:1). It is dirt cheap, fanless and small enough to throw in a bag, can’t go wrong with this one. Need a temporary tap to monitor traffic? Just pop it inline and you are good to go.


If you are more of a DIY kind of person, I’d suggest the ESPRESSObin.
It sells for about $50 and is a single board computer with Gigabit network interfaces and a SATA interface. It is based on ARM architecture and runs Linux.
Since it has multiple Gbit interfaces and you can hook a HDD up to it you have a wide array of possibilities you could use it for. A lot of network traffic monitoring situations come to mind, where you would want to keep copies of the traffic in question for later analysis.


Another little useful device is the EdgeRouter X from Ubiquiti.
As the name suggests it’s a router and sells for about $55 The nice thing about this device is that it runs Linux (or more specifically a fork of Vyatta), so you can dig into it to get it to do things not available on the GUI.
5 Gbit ports, RIP and OSPF routing protocols, usual SOHO features like Firewall, VPN, QoS. Behaves a lot like a switch with some routing functionality. Unfortunately I couldn’t get port mirroring to work reliably but aside from that it’s still an impressive little router.


Native tcp/udp sockets in bash cheatsheet

Bash has a nifty feature to open tcp and udp connections and read/write data to that connection. The Advanced Bash Scripting Guide and the bash man page offers some information and examples, and google has some odd examples, but all in all there isn’t much variety of information on the internet on the topic. This feature is enabled in Bash at compile time with the flag –enable-net-redirections

It works by assigning a connection to a file descriptor with exec. Protocol must be udp or tcp, hostname must be either an IP or a FQDN. Use any free file-descriptor (3 or higher usually).

Use &- to close the connection instead of leaving it in the CLOSE_WAIT status.

Basic Example:

You may have noticed that the cat will hang around a while after delivering the content. As long as the connection is established it will sit there and wait for data, which can be quite a while depending on the daemon on the other end. If you want to avoid having to wait, kill or ctrl-c the cat  you can use read with an input timeout.

In the example if read has to wait longer than 2 seconds (-t 2) it will abort reading from the network connection.

If you only want to read a single line you can use head:

Although this will have the same timeout problems as cat if there is no more data but the connection is still established, it is useful and quick if you know exactly what kind of result you are expecting.

You don’t have to read the response right away, it will be buffered until you get around to accessing it (even if the other end terminates the connection).

MySQL selecting IPs via CIDR

Quick little snippet here for selecting IPs from a database based off a CIDR subnet. First off a table structure with some test data:

Now let’s say we want all IPs from the subnet, using a simple 173.192.175.% would provide false results since you don’t want the whole /24.

If your IP is stored as an unsigned int (good for you) than you can use this snippet to search for matching IPs:

If your IP is stored as a varchar (for whatever reason), the only difference is a inet_aton() around the IP field.

No matter which one you use, the result will be: