/proc/sys/net/core/rmem_default      (default receive window)
/proc/sys/net/core/rmem_max          (maximum receive window)
/proc/sys/net/core/wmem_default        (default send window)
/proc/sys/net/core/wmem_max            (maximum send window)

/proc/sys/net/ipv4/tcp_rmem    (memory reserved for TCP rcv buffers)
/proc/sys/net/ipv4/tcp_wmem    (memory reserved for TCP snd buffers)