Some of you might remember me some not anyway this is Sysop_fb. I saw a few people writing posts and asking questions in regards to QNX, although some of what I discuss could in essence be used on one of the newer versions I haven't had an oportunity to look at the newer versions.

QNX 4.25 is a Real-Time OS and is in my own opinion a unix flavor, it's very stable and very reliable. You can pretty much design the system to meet your own needs although it is not open source and up until 6.0 was release a development studio for QNX 4.25 would cost in the thousands of dollars. Since it's not open source it does have its limitations.
QNX is mostly used in the business world as it is not free, you have to buy a licsense to install QNX, although there is free trials available.
Networking
QNX 4.25 uses a similiar networking type structure as a router, it requires hard routes to be placed in the sysinit.1 file to designate how you want QNX to get to one subnet from it's current subnet.
Now to get the box on your home lan, you will need to know the mac address of the NIC, the ip of the gateway(depends on your network setup, if you have dsl your modem will be your gateway), and an ip address for your QNX box and ofcourse the ip address(s) of your nameservers.
vedit /etc/hosts and add the ip address of your box in with whatever name you prefer as so
192.168.0.5 <tab> thisboxsucks

Next
vedit /etc/config/netmap
add the mac address of the card as so
1 1 00E778 87EFE2

Next
vedit /etc/config/sysinit.1
Make sure the appropriate drivers are in for your NIC
such as

Net &
Net.ether82557 <-- the driver that pertains to my NIC
next go down to below where the script initializes netstart and below it write in the route.
/usr/ucb/route add default <gateway ip goes here>
such as
/usr/ucb/route add default 192.168.0.1

Next
vedit /etc/resolv.conf
uncomment the nameserver lines and add in the appropriate ip's for your nameservers.

Next
vedit /etc/netstart
replace node$NODE with whatever you called your box
such as
/usr/ucb/Socket thisboxsucks &

/usr/ucb/ifconfig en1 thisboxsucks up

Next make sure an ethernet cable is plugged into the NIC and reboot the box
shutdown -f
I might have forgot something feel free to correct me this is mainly geared towards simple home networks.