Community string check.

Signed-off-by: Leo Ma <leoma@credosemi.com>
Community string check

Signed-off-by: Leo Ma <leoma@credosemi.com>
Bug fix: String passing without end character '\0'

Signed-off-by: Leo Ma <leoma@credosemi.com>
Merge pull request #4 from leo-ma/master

New Feature: community string check and port configure.