I notice when I send udp packets from computer A to computer B, B can receive the upd packets correctly but if I send udp packets from computer B to computer A the udp packets are not received
A and B are not in the same network, and they are all with public IP, they are not behind NAT.
does this mean there is a firewall in between which prevents A from receiving udp packets from B? if A sends some udp packets to B before B sends udp packets to A, will the firewall remember this and then allow the udp packets from B to A ?
I know TCP is stateful and so firewall have a lot of measures to block some malicious TCP packets, like TCP SYN flooding, but how firewall block UDP packets? are there any good articles about this?
because A is my computer in a office. I want to build a system so that a UDP program on A can receive packets from outside. But it seems the firewall filters all the incoming udp packets. I'm wondering, if I use a commercial UDP-based program, like UDP-based video streaming tool or website, can I watch videos?