This is in respect to bypassing Captive Portals. I haven't tried it yet on a captive portal yet. But I was wondering, what will happen if :

  1. I connect to a wireless network
  2. Get the router's MAC address by using "arp -a" command.
  3. Change my device MAC address to router's MAC address.

In this scenario, lets assume :

  1. The captive portal is not configured for proper security and it is only looking at the MAC addresses of the clients connected.
  2. Authenticated MACs can browse the internet whereas others without authentication get through the captive portal.

2 Answers 2


Each device on the network maintains a table of known ip-mac address mappings. It builds this table based on arp packets. (this is what you see when you type arp -a) You can see these arp packets going over the network if you open up wireshark.

If you were to do as you suggest, and change your machine's mac address to mimic that of the gateway's mac address, I suspect nothing would happen. Mainly because all of the other devices on the network would maintain their original mapping to the default gateway.

In order to spoof other devices on the network you need to force them to update their arp tables.

You can use arpspoof to do this.

Arpspoofing is pretty easy


Most probably:

  1. you would loose access to the internet, as your PC's default gateway is IP of the router and guess how your PC reaches it ? - via asking for its MAC address, so your PC would know that to reach the internet it should talk with itself .
  2. option to intercept other PC's traffic is not relevant here as in WiFi you do it a bit differently as opposed to LAN (and is easier).

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