esp-idf/components/lwip/Kconfig

menu "LWIP"

config L2_TO_L3_COPY
    bool "Enable copy between Layer2 and Layer3 packets"
    default 0
    help
        If this feature is enabled, then all traffic from layer2(WIFI Driver)
        to layer3(LWIP stack) will make a copy, the layer2 buffer will be
        freed and the copy will be sent to layer3. Please be notified that the
        total layer2 receiving buffer is fixed and ESP32 currently supports 25
        layer2 receiving buffer, when layer2 buffer runs out of memory, then the 
        incoming packets will be dropped in hardware. The layer3 buffer is 
        allocated from the heap, so the total layer3 receiving buffer depends 
        on the available heap size, when heap runs out of memory,  no copy will
        be sent to layer3 and packet will be dropped in layer2. Please make sure
        you fully understand the impact of this feature before enabling it.

config LWIP_MAX_SOCKETS
    int "Max number of open sockets"
    range 1 16
    default 4
    help
        Sockets take up a certain amount of memory, and allowing fewer
        sockets to be open at the same time conserves memory. Specify
        the maximum amount of sockets here. The valid value is from 1
        to 16.

config LWIP_THREAD_LOCAL_STORAGE_INDEX
    int "Index for thread-local-storage pointer for lwip"
    default 0
    help
        Specify the thread-local-storage-pointer index for lwip
        use.

config LWIP_SO_REUSE
    bool "Enable SO_REUSEADDR option"
    default 0
    help
        Enabling this option allows binding to a port which remains in
        TIME_WAIT.

config LWIP_DHCP_MAX_NTP_SERVERS
	int	"Maximum number of NTP servers"
	default 1
	range 1 16
	help
		Set maxumum number of NTP servers used by LwIP SNTP module.
		First argument of sntp_setserver/sntp_setservername functions
		is limited to this value. 

endmenu