Re: [lwip-users] How to limit the UDP Rx packet size to avoid big RAM allocations

[Sergio R. Caprile]

UDP datagrams are carried by Ethernet frames. It is not lwIP but your
driver who allocates memory to hold those frames before handling them to
lwIP, which in turn will deliver to your application. The only way to
stop allocation is there.
Someone could also send pings of death, repeated SYNs...
If you need firewall functionality, you need to build a firewall.