On Wed, Jan 11, 2006 at 05:36:27PM +0000, Simon Hobson wrote:
Ted Harding wrote:
A couple of distinct questions.
- Computers on a LAN are "behind" an ADSL modem/router
which faces out to the Net.
Seen from outside, this router has IP address
PPP.QQQ.RRR.SSSFrom inside the LAN it can be accessed either from the above address or from an "internal" IP address
192.168.1.1On the LAN are sundry machines with IP addresses
192.168.1.yyyor (on a subnet)
192.168.0.zzzQuestion: Is there any way by which one can address one of the "internal" machines from outside (i.e. the Net).
Clearly, for instance,
telnet PPP.QQQ.RRR.SSSwould at best connect to the router (which does respond to telnet, by the way).
What I'm wondering is if there's anything like
telnet @PPP.QQQ.RRR.SSS!192.168.1.yyyi.e. to "route" the telnet request for connection to the internal machine at 192.168.1.yyy through the externally visible address PPP.QQQ.RRR.SSS
What you want is "Port Forwarding". Tell your server to forward a
... for 'server' read 'router' in this instance.
port to an internal address, for example if you forward port 1023 to port 23 on 192.168.1.17 then you can do "telnet PPP.QQQ.RRR.SSS 1023" and get connected to the machine at 192.168.1.17 - though I'd advise using SSH (port 22) rather than telnet.
Home routers tend to only support a limited number of forwarded ports
- and they may call it something different (servers,gaming, and a few
other things have been seen). One way round this is to port forward SSH to just one machine, then use the port tunneling facilities of SSH - this is what I do to access stuff at home.
My Zyxel router has all this in the firewall set up. I have three rules set up at the moment and it's using 2% of the available space.