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I know there are ways to defend yourself against wireless attacks targeting routers such as changing default creds and implementing a firewall but are there any other techniques that'll increase your router's security?

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Keep the firmware up-to-date, research the possible exploits before buying the router, do a port scan from inside and outside the LAN to see what is exposed on different interfaces, disable remote access to the admin pannel (or filter it by a static ip that you know only you or authorized people can send pakets through).

Lastly, do a security assesment on the software, most decent routers actually run a modified linux version, custom made for them, and you can get a root shell by soldering some pins on the serial console and connecting to them using a UART to usb adapter (finding the baud rate and the right pins might be tricky at first, but there are tools and tutorials out there), you can significantly increase the security of your router by disabling unwanted services, unwanted iptable rules and super admin accounts (funny story here, I have found such an account on a router deployed by the ISP, the super user account was so baked in that changing the password bricked the device and it was the only account that could login into SSH).

Keep in mind that most attacks will come from publicly available exploits, treat your router as if it were your PC or your production server.

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  • What do you mean do a port scan inside and outside the LAN? I know I can do a full port scan using nmap -p- <ip address> and could also add a few more options for more information. Is that how you would scan inside or outside of the LAN? And how do you scan the opposite? Also, is it possible to spoof your IP that can trick the router into thinking that you are another person who is allowed to send packets through? Feb 7, 2021 at 1:53
  • @MatthewSchell maybe my phrasing wasn't that good, I meant scanning yout public IP from a machine outside the LAN, running nmap -p- <router ip> from inside the LAN you will see what the ports is the router exposing to computers connected to your LAN, running nmap -p- <your public ip> from a random computer outside the LAN will show what ports are exposed publically to everyone on the internet (doing that from inside the LAN will most probably show you the same ports as with the nmap scan on the router's LAN IP).
    – Zicar
    Feb 7, 2021 at 2:30
  • You could view routers as having 2 IPs, one that is exposed to computers connected to the LAN and one exposed to the internet, this way you can check what the attack surface looks for people that are already connected to the network, and also the attack surface that any internet scanner would see.
    – Zicar
    Feb 7, 2021 at 2:30
  • I don't really understand the question about IP spoofing, but, in general, you can send a spoofed IP layer packet with another IP as the source, but the destination would send the repy to the IP you have spoofed, not yo you, this could be a problem only if the server that receives it uses a VERY badly designed protocol over UDP, with protocols over TCP you are going to be fine since you need to know a lot about an already established connection and you can't start a new connection since the TCP handshake requires you receiving a reply and sending a packet with some data from that repy.
    – Zicar
    Feb 7, 2021 at 2:42
  • If you were refering to someone spoofing the administration IP set for remote access to the admin pannel, the answer is no (unless it's a bug in the firmware), websites use TCP (unless they are using HTTP 3, but that's not badly designed). What I meant by "a static ip that only authorized people can send pakets through" was that you should choose an ip for administration outside the LAN that you know it's reserved for you and it won't be assigned to another computer on the internet or that other random people can send data through (don't use the ip from a VPN provider, or one from TOR, etc.).
    – Zicar
    Feb 7, 2021 at 2:59

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