Access PC via router WAN login?

[marklodge]

Is it possible to gain access to the internal LAN via WAN login on a broadband (ADSL) router, if I know the router password?
Assuming i have access to the administration interface via WAN login and the router does have VPN, port forwarding & routing table modification functionality, then how exactly will it be done?

[MrByte]

Depens on what you call "access". If you're in full control of the router, you can configure port forwarding so that you can access some services of the PCs of the internal LAN, such as file & print sharing or remote desktop connection, but you still need to know the login/password to access them. If these services are not password-protected, then yes, the computers of the internal LAN are in danger, as your control of the router basically means that they're no longer firewalled.

[marklodge]

so, if file sharing is not enabled on the pcs connected to the internal lan it is impossible to access the files?

[MrByte]

There are alternative ways to access files, for example Remote Desktop Connection (built-in Windows service) or similar third-party software, such as RAdmin ( [url]http://www.all-nettools.com/remote-control-5/radmin-remote-control-2**74.htm[/url] ). Besides, the PCs may be running FTP servers. But if none of the above is running -- then yes, it's impossible to access the files.

[marklodge]

There are alternative ways to access files, for example Remote Desktop Connection (built-in Windows service) or similar third-party software, such as RAdmin ( [url]http://www.all-nettools.com/remote-control-5/radmin-remote-control-2**74.htm[/url] ). Besides, the PCs may be running FTP servers. But if none of the above is running -- then yes, it's impossible to access the files.

OK, so , to fully secure PCs behind NAT routers I do not need to install a firewall to monitor incoming traffic?

I just need to disable RDC and make sure no ports are open, correct?

But what if i need some ports to be open for bittorrents etc?
what are the implications of leaving ports open?
What is a malicious user able to do if i have forwarded port say: *2*45 to my ip: **6.25.75.* ?

could that be used to access my files?

[MrByte]

OK, so , to fully secure PCs behind NAT routers I do not need to install a firewall to monitor incoming traffic?

A firewall is always a good thing to have. You don't necessarily need to "install" it, i.e. you don't necessarily need a *-rd party product, but you should at least use the built-in Windows firewall.

I just need to disable RDC and make sure no ports are open, correct?

I'd say "to make sure no ports offering access to files are open". If you completely close all ports, you won't be able to use many services, such as Skype.

But what if i need some ports to be open for bittorrents etc?
what are the implications of leaving ports open?
What is a malicious user able to do if i have forwarded port say: *2*45 to my ip: **6.25.75.* ?

could that be used to access my files?

Open ports, by themeselves, are not dangerous. Any computer has open ports, you can't be networked without open ports. What's important is that such ports shouldn't be exposing any data not intended for "outsiders". If you're running a local FTP server intended only for your LAN computers, make sure that either FTP access is password-protected or that your firewall restricts access to local IP addresses only. Bittorrent shouldn't be a problem.