Nmap scans filters:

TCP Connect Scans

tcp.flags.syn==1 and tcp.flags.ack==0 and tcp.window_size > 1024

SYN Scans

The given filter shows the TCP SYN scan patterns in a capture file.

tcp.flags.syn==1 and tcp.flags.ack==0 and tcp.window_size <= 1024

UDP Scans

The given filter shows the UDP scan patterns in a capture file.

icmp.type==3 and icmp.code==3