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Michael Horowitz 
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Turn Off Stuff

One way that consumer routers compete is on features. No doubt, the vendors think people will buy the router with the most features. But features can be bad. The less software that's running, the safer you are. Techies refer to this as reducing the attack surface.

What follows is a list of router features that most people can turn off most of the time. If you need it, fine. But, if not, turn it off.

Every router will not have every feature listed below and there will be times when a certain feature can not be disabled.

  1. WPS. Always turn this off. Better yet, don't buy a router that supports it.
  2. UPnP and NAT-PMP are two different protocols that do the same thing - they let devices on your network poke holes in the router firewall. This makes setup of some new devices easier, but is a huge security hole. It is how IoT devices make themselves visible on the Internet, where many of them get hacked, either due to security flaws or the use of default passwords. UPnP was from Microsoft, NAT-PMP was developed by Apple. Many routers only support UPnP, Apple routers support NAT-PMP and higher end routers support both. Turning these protocols off may break something. If it does, then you need to make a choice: either live dangerously or setup the necessary port forwarding manually.
  3. Remote administration. This is the function that lets someone on the Internet access the web interface of the router. It is also commonly called "Remote Management" and there may be other terms for it, such as "Web Access" too. Peplink calls is "Web Admin Access." See examples from TRENDnet and Cisco.
  4. Telnet access to the router on both sides (WAN and LAN). An October 2016 study by ESET found that Telnet access was available from the LAN side in more than 20% of the 12,000 routers they tested.
  5. SSH access to the router. Here is one example of why SSH should be disabled: Akamai Finds Longtime Security Flaw in 2 Million Devices. Peplink refers to it as CLI SSH (CLI = Command Line Interface).
  6. IP version 6 (a.k.a. IPv6) then test that it is really off at whatismyv6.com. In 2013 someone discovered a bug in IPv6 regarding fragmentation buffer overflow. Just having IPv6 enabled made you vulnerable.
  7. SNMP. It can be used in an amplified reflection attack, where a small command generates a ton of output.
  8. Sharing of devices plugged in to a USB port, if possible. File sharing may be referred to as SAMBA. The NetUSB flaw left an untold number of routers vulnerable to attack. Asus in particular has had multiple problems sharing files in a USB port. Asus owners should consider turning off all three AiCloud features: 'Cloud Disk,' 'Smart Access,' and 'Smart Sync'. Quanta routers were found to have four backdoor accounts in Samba.
  9. HTTP access to the router. If possible, only use HTTPS
  10. Access to the web interface on ports 80 and 443. That is, always administer the router via a non-standard port
  11. Cloud based management. This relatively new feature competes with Remote Administration, it is another way to administer a router. The company that makes the router will offer a cloud management website from which anyone who knows the password can re-configure the router. To me, this means trusting every employee of the router vendor. No thanks to that.
  12. VPN passthrough for PPTP VPNs. PPTP is the least secure type of VPN, this insures you don't use it. If you don't use a VPN at all, then also turn off passthrough for the other types of VPNs.* But, you should use a VPN, even at home.
  13. VPN server(s)
  14. Bonjour
  15. DLNA Media server and/or DLNA media sharing
  16. iTunes server
  17. FTP
  18. DDNS (Dynamic DNS) If doing Remote Administration, this may be needed.
  19. DMZ. It places computers virtually outside the router firewall. It should be off by default, but you should check it every now and then in case router was hacked. See an Asus UI sample.
  20. Port Forwarding. Should be off by default. That said, there are defensive measures that do port forwarding to known bad IP addresses, so this feature can swing both ways. Note than TRENDnet calls this feature "virtual server"
  21. Port triggering. See an Asus UI sample.
  22. Guest networks, when not in use
  23. WiFi whenever possible, such as overnight. If you are very lucky, the router can schedule this. If you are somewhat lucky, there will be an on/off button for WiFi.
  24. RIP v1, aka Routing Information Protocol version 1. Probably not installed, as the protocol is extremely old, but if its there, turn it off. It is more likely to be installed on routers running DD-WRT.
  25. If you are using the Google OnHub router, turn off the features that deal with "smart devices", that is: Bluetooth Smart Ready, Weave and 802.15.4.
  26. AirPrint

*On episode 510 of the Security Now! podcast, Steve Gibson read an interesting note from a listener who had turned off all VPN passthrough on a router. Sure enough, a user on the network was using a VPN, but the story is more interesting than that. Search the transcript for "Nathan in Kansas". The episode aired June 2, 2015.

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This page was last updated: March 29, 2017 10PM CT     
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