How to stealth port 113 on a DI-604 router

[MadDoctor]

I bought it
I changed the password
I didn't configure it
but I want to stealth port 113 (it is hidden)
What basic configuration stuff should I do with this router?

[Philip]

I believe port 113 is better off closed than stealth... Check out the description of port 113 here: http://www.speedguide.net/ports.php

I'd run the SG Security scan and see if there are other open ports that might need looking into.

[MadDoctor]

Thanks Philip. Looks like I'm very secure. :)

Now if I’m secure on an emotional level is a new subject entirely. I think I’m pretty good but the wife says that a guy of my age should not be dependent on a “cuddle” blanket. I really don’t need the blanket, it’s just a little easier to justify at a meeting than my pet bear. Too many people in the world looking to find flaws in other people I guess. ;)

[TonyT]

but the problem with filtering/stealthing port 113 is that if legitimate requests get no response at all from port 113 queries, the connection to them (which initiated their query in the first place) will be delayed or perhaps even completely abandoned.

This is true, but I have found no common client that has problems if this port is completely filtered. Email, browser, ftp clients all work fine if this port is filtered.

The best way to filter this port (stealth it) completely is to use the router port forwarding feature. This is done by forwarding port 113 to an ip address on the lan that will never be used, such as 192.168.1.250.

Any home router that uses DHCP will never assign a client system xx.xx.xx.250 and it's also unlikely that a home system will ever have 250 computers hooked up.

What this accomplishes is that any time a server or potential hacker asks for port 113, the router will forward this request to the machine address of 192.168.1.250, an dbecause there is no machine at that ip, the router will drop the request and will not respond to the server or hacker that is asking for it.

Try using port forwarding and you will see that you will likely have no issues with any client applicatuions, and if you do, just stop the port forwarding.

BTW, I have 6 systems on my lan (5 windows and a linux server) and all the kid's systems use extensive numbers of media and messanging apps, and none have ever had any issues because I have port 113 stealthed by using the router port forwarding.

The adverse effects of this are more common to windows server operating systems on a lan, esp if using a local proxy server.

[MadDoctor]

The best way to filter this port (stealth it) completely is to use the router port forwarding feature. This is done by forwarding port 113 to an ip address on the lan that will never be used, such as 192.168.1.250.

DING DING DING!!! We have a winner!!!! 113 is now stealthed and it allows traffic.

Thanks Tony (rep point on the way...)


[Darn... I went against Philip. He could crush me like an ant. I'll suck-up to him and see if I can slide under his radar. I play this right and I might even pick up some reputation points!!!!]

[MadDoctor]

[sucking up to Philip]
Philip -

I gave Tony’s suggestion a try and it worked but... I quickly reverted the settings back so the port is blocked and not stealth’ed.

I know you are the man, the go-to-guy, the one that controls my post count and can and or remove reputation points. I simply wanted to give it a try so I can say “it can be done” knowing I’d never actually stealth it... just block it.

[removes lips from Philips butt]

*Goes back to spitting sun flower shells over deck railing*

[TonyT]

I gave Tony’s suggestion a try and it worked but... I quickly reverted the settings back so the port is blocked and not stealth’ed.
Why on earth did you do that? Now, if some slimeball scans your system, the router WILL respond and send a message back that port 113 is closed. This lets the scanner know with certainty that a computer exists at your ip address. Even though no ports are open for access, he knows you exist and can now attempt other exploits, esp ms security holes.

Realize that port scanners are not all the same. Some are more powerful than others, and online port scanners like the one here at SG is no where near as efficient and robust as something like nMap and other linux software.

[MadDoctor]

Why on earth did you do that?
Just pulling your leg Tony. I'm all stealth’ed. (thanks)

[TonyT]

Just pulling your leg Tony
...looks down toward floor and sure enough there is a hand on my shin...nice nail polish you got there MadDoctor!

[MadDoctor]

Glad you like the nail polish.

*moves hand down Tony’s shin*

Why are you wearing fish-net nylons?