Hi @osung1598,
Sorry for the delay.
IO17 and IO18 pins are available on the UART port. You can connect to them via the DF13 6-pin jumper cable from the Navio2 package.
GP26 pin on Raspberry header is available for programming too, but you’ll need to use the extension header to get physical access to it.
You can access the configuration of either of these ports with the “Relay Switch” function. Please, take a look at this article in our docs.