dslreports logo
 
    All Forums Hot Topics Gallery
spc
Search similar:


uniqs
4389
Amar7
join:2001-07-20
Surrey, BC

Amar7

Member

E4200 V2 NAT Loopback

Can someone who has this router see if it supports NAT loopback? Cisco support was pretty useless in this regard.

Mike Wolf
join:2009-05-24
Tuckerton, NJ

1 edit

Mike Wolf

Member

I don't see an option for it, but I can take screenshots of each page and send them to you if you want.

There are four options under the Internet Firewall settings

Filter Anonymous Internet Requests
Filter Multicast
Filter Internet NAT Redirection for IPv4 Internet Only
Filter IDENT (Port 113)
Amar7
join:2001-07-20
Surrey, BC

Amar7

Member

I don't think its typically configurable. Either the router allows it or it doesn't. Can you try accessing your public ip from a computer within the LAN and see what happens? It would be easiest to test if you are forwarding some port to one of the computers on your lan. For example: if you forward port 8080 to 192.168.1.2, try to access :8080 from a different computer on the lan. If it works, NAT loopback is supported.

Mike Wolf
join:2009-05-24
Tuckerton, NJ

Mike Wolf

Member

Doesn't look like it does, sorry.

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

1 edit

Bill_MI to Amar7

MVM

to Amar7
I can't confirm the exact function but here's what I think may be it:
»ui.linksys.com/files/E42 ··· all.html

The setting is "Filter Internet NAT Redirection" and appears to be ON by default. The HELP provides a little more confusion. Poorly worded at best.

I also have this setting on a E3200 at work, figured it was probably loopback, but we're running AP-only.

General tip: Browse Linksys router setup pages starting here: »ui.linksys.com/files/
They're not too out of date and a lot better than nothing.

Mike Wolf
join:2009-05-24
Tuckerton, NJ

Mike Wolf

Member

oh wow this is amazing thanks for the link. Hope it helps him.

I followed the instructions both all of those options on and off and I didn't see a difference.
Amar7
join:2001-07-20
Surrey, BC

Amar7 to Bill_MI

Member

to Bill_MI
said by Bill_MI:

I can't confirm the exact function but here's what I think may be it:
»ui.linksys.com/files/E42 ··· all.html

The setting is "Filter Internet NAT Redirection" and appears to be ON by default. The HELP provides a little more confusion. Poorly worded at best.

That actually sounds like exactly what I'm looking for.

@Mike My previous post somehow got screwed up. It was supposed to say "if you forward port 8080 to 192.168.1.2, try to access XX:XX:XX:XX:8080 from a different computer on the LAN where XX:XX:XX:XX is your public IP. Do you mind trying that out with the setting Bill mentioned disabled?

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

1 edit

Bill_MI

MVM

Amar, I wish I could test it at work but the boss wouldn't like it. Chances are, any E series will have the same setting.

In general, loopback has been a staple in Linksys routers over the years - and I can't imagine what else this setting could possibly be. I'd give it 99% chance it's loopback (since nothing is 100% ).

Mike, do you have a grasp of what loopback is? You have to be hosting a server to the world and everyone in the world can get to that server by pointing to your public IP... except those on your LAN where that server is.

This is where loopback comes in. It's considered a hack, actually . At the packet level some trickery must be used. But machines on your LAN can access that server by the public IP. Without loopback, they need to use the LAN IP. Hope you get the idea.

Mike Wolf
join:2009-05-24
Tuckerton, NJ

Mike Wolf to Amar7

Member

to Amar7
Alright. I turned off all of the firewall settings including the SPI firewall protection.

I have a media server running on one of my systems so I pointed the direction to there.

I can remote desktop into my router with the external IP address:8080 both on the LAN and through the internet itself and also just with the external ip address itself on the LAN but only when the SPI firewall protection is turned off and the remote management feature is on.

I can access the computer with remote desktop on the LAN when the firewall is configured, and I can access the computer with remote desktop through the internet itself with the IP address with the DMZ settings.

I then repeated both of these things with
Filter Anonymous Internet Requests, Filter Multicast, Filter Internet NAT Redirection for IPv4 Internet Only and Filter IDENT (Port 113) turned on (leaving the SPI firewall protection off) and everything still worked fine.
I hope this helps.
Mike Wolf

Mike Wolf to Bill_MI

Member

to Bill_MI
Does that have to do with a DMZ server?

Incoming traffic from the Internet is usually discarded by the router unless the traffic is a response to one of your local computers or a service that you have configured in the Port Forwarding/Port Triggering screen. Instead of discarding this traffic, you can have it forwarded to one computer on your network. This computer is called the default DMZ server.
Amar7
join:2001-07-20
Surrey, BC

Amar7

Member

Thanks for all the help guys. I really appreciate it.

Bill_MI
Bill In Michigan
MVM
join:2001-01-03
Royal Oak, MI
TP-Link Archer C7
Linksys WRT54GS
Linksys WRT54G v4

Bill_MI to Mike Wolf

MVM

to Mike Wolf
said by Mike Wolf:

Does that have to do with a DMZ server?

Hosting a server is done with port forwarding and DMZ is a form of exactly that. You could call DMZ (as Linksys defines it) like a "default forward".

So yes, loopback should work with a port forward or DMZ.

Amar, I hope Mike's good data helps you out. Good luck and tell us how it goes.

Snookie
@209.212.21.x

Snookie

Anon

Ah yes I've been reading this for a while and I had a feeling Mike was right. I'm so glad to hear that everything worked out for the best. Good luck to you all old chaps.

Mike Wolf
join:2009-05-24
Tuckerton, NJ

Mike Wolf to Bill_MI

Member

to Bill_MI
I came across this info off the router help page, not sure if it's relevent or not.

Filter Internet NAT Redirection for IPv4 Internet Only: This filter prevents a local computer from using a URL or Internet IPv4 address to access the local server.