How to add a route in debian?

Question

Debian

[email protected]:/# route add -net 10.1.100.0/24 via 10.1.123.1 dev eth0
Usage: inet_route [-vF] del {-host|-net} Target[/prefix] [gw Gw] [metric M] [ [dev] If]
inet_route [-vF] add {-host|-net} Target[/prefix] [gw Gw] [metric M]
[netmask N] [mss Mss] [window W] [irtt I]
[mod] [dyn] [reinstate] [[dev] If]
inet_route [-vF] add {-host|-net} Target[/prefix] [metric M] reject
inet_route [-FC] flush NOT supported

What does he not like? always did this before
still did this

route add -net 10.1.100.0 netmask 255.255.252.0 gw 10.1.123.1 dev eth0

everything was working before