Subnet Mask support on 6.2.1

Hi all

The system described below is totally closed loop and not connected to a network! So don’t worry about the ip address allocations!

I have a 6.2.1 qnx system with an ip of and a subnet mask of I have this connected with a cross over cable to a windows xp machine with an ip of with a subnet of They ping each other with no problems. I then set the subnet on the qnx system to and i can still ping from the windows system! :question:

I then change the qnx subnet to and I can still ping from the windows system. I then change the subnet to which should change the allowable range of ip’s to be to I can still ping from the window system!!

I then use ifconfig en0 to change the subnet to to see what happens and qnx ignores this but sets the subnet to Does this mean qnx only supports the first octet of the subnet and ignores the rest? Qnx should see this as a class B and default it to right?

What should I set the subnet too on the qnx system to break the communication link to the windows system?


Everytime you change a netmask (to test), remember do a “arp -d” to delete the XP’s ip in arp entry,
before you try the “ping” command.

Thanks for the response.

I was using “ioctl()â€