> What ports on firewall must be opened to discover and to  manage nodes on
192.168.1.xxx network ?

You can probably get away with:
ICMP ping (type code 8) out, ping responses (type code 0 ) back.
SNMP (UDP/TCP port 161) out and responses back.

The exact firewall rules will depend on the capabilities of the firewall.

Note that unless you have SNMP enabled on the firewall, you probably won't
discover them and you'll need to use either seedfiles (edit
/usr/OV/conf/netmon.seed) or loadhosts (run "echo ipaddress hostname
|loadhosts -m subnetmask") to load the devices into NetView.