If there is a "network <network number>/<mask> area <area ID>" command present in the Quagga configuration, the "ip ospf area <area ID>" command is rejected with the error "Please remove network command first." This prevents you from configuring other areas on some of the unnumbered interfaces.
Steps to Reproduce
Here is a sample configuration from ospfd.conf that illustrates the problem:
router ospf log-adjacency-changes detail ospf router-id 0.0.0.17 network 18.104.22.168/8 area 0.0.0.0 passive-interface swp4 passive-interface swp5 passive-interface swp6 passive-interface swp7 passive-interface swp8 ! interface swp1 ip ospf area 0.0.0.0 ! interface swp2 ip ospf area 0.0.0.1 ! interface swp3 ip ospf area 0.0.0.1 !
Cumulus Linux supports both commands, but not in the same configuration.