If LCP keepalive mechanism is enabled in menuconfig, it's statically
configured on creation of an interface and cannot be changed runtime. In
some cases it's useful to relax LCP criteria during runtime operation,
for example before initiating OTA. This config option allows for
disabling already enabled LCP echo (this setting becomes effective after
reconnecting, i.e. initializing a new session)
Closes https://github.com/espressif/esp-protocols/issues/287
To allow setting auth_type to PPPAUTHTYPE_NONE, add NETIF_PPP_AUTHTYPE_NONE
to esp_netif_auth_type_t.
So even PAP/CHAP are enabled in lwIP, the application still can set
auth_type to PPPAUTHTYPE_NONE.
Signed-off-by: Axel Lin <axel.lin@gmail.com>