firewall question filtering SYN packets

Hi

I was wondering how I can block SYN packets from the forward chain.

In linux I can set a mask and check the value of the tcp flaps

I tried

add action=accept chain=YBFWDIN comment=“allow non SYN tcp traffic” tcp-flags=!syn protocol=tcp


but I had to add

add action=accept chain=YBFWDIN comment=“allow SYN,ack tcp traffic” tcp-flags=syn,ack protocol=tcp



so in forward I jump to YBFWDIN if in-interface=!ether1

I suppose I could try connection-state (just thought of that as I was typing)
add action=accept chain=YBFWDIN comment=“Allow non SYN connections” connection-state=!new

??