使用proftpd -d9 -n启动就会已下提示
serverp61911407160003 proftpd[29954] 10.6.5.123: Failed binding to 0.0.0.0, port 21: Address already in use
serverp61911407160003 proftpd[29954] 10.6.5.123: Check the ServerType directive to ensure you are configured correctly.
serverp61911407160003 proftpd[29954] 10.6.5.123: Unable to start proftpd; check logs for more details