I think nc has changed behavior. Using nmap I get more consistent results. nmap -iL /dev/shm/list.txt -sU -p53 nmap -iL /dev/shm/list.txt -sT -p53 /d

I think nc has changed behavior. Using nmap I get more consistent results. nmap -iL /dev/shm/list.txt -sU -p53 nmap -iL /dev/shm/list.txt -sT -p53 /dev/shm/list.txt being a list of open resolvers and other UDP listeners on the internet. Give nmap a shot if testing.