How much memory is consumed by the Linux kernel per TCP/IP network connection?

Question

How much memory on average is consumed by the Linux kernel (in kernel address space) per TCP/IP network connection?

Answer 1

Also depends on which layer. In case of a pure bridging scenario, there's just the bridge-level FDB. When routing comes into play, there's the routing table and the IP-level FDB/neighbor db. And finally, once a local socket is in the play, you have of course window size, socket buffers (both send and receive, and they default to 128k last time I checked), fragment lists (if used), so that is where your memory goes, but a clear-cut answer is hard to make with all the parts in use. You can use ss -m to obtain a few memory statistics of local stream sockets.