Addressing a machine behind the router without port forwarding or DMZ

[Dotan Cohen <dotancohen@gmail.com>]

Not a Debian-specific question, but I turn to the best brains that I know.

Assuming a LAN with a router and three machines:
10.0.0.1 Router
10.0.0.2 Computer1
10.0.0.3 Computer2
10.0.0.4 Computer3

The router sits on an outside IP address of 123.45.67.89. There is no
DMZ or port forwarding assigned on the router to any of the other
machines.

Is there any way an individual from outside the LAN could access a
resource (Apache for instance, or SSH) on Computer1 assuming that he
knows Computer1's LAN IP address? Would this this be possible if he
had access to Computer1 and could configure it somehow (without
configuring the router)?

Thanks.

-- 
Dotan Cohen

http://gibberish.co.il
http://what-is-what.com