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You can handle L4 protocols in userspace. You can bind to a particular IP protocol number. You can even handle L3 in userspace. Obviously if you do this you lo
by richardwhiuk 4y ago
You can handle L4 protocols in userspace. You can bind to a particular IP protocol number. You can even handle L3 in userspace.
Obviously if you do this you lose the ability for multiple applications to handle different "ports", unless you do the multiplexing in userspace as well.
- derefr 4y agoYou have a unique definition of "handle" that doesn't seem to include "your OS's kernel packet filter keeps working to pre-filter these packets based on an L4 understanding of them before handing them to userspace, or after being handed them by userspace." Which, if your machine is acting as something like a router/NAT/firewall, is kind of... the entire point of the box being there in the communication path.