use aria2c --enable-rpc --rpc-listen-all fail

When i use “aria2c --enable-rpc --rpc-listen-all” it have exception: 04/05 22:43:41 [WARN] Neither --rpc-secret nor a combination of --rpc-user and --rpc-passwd is set. This is insecure. It is extremely recommended to specify --rpc-secret with the adequate secrecy or now deprecated --rpc-user and --rpc-passwd.

04/05 22:43:41 [ERROR] IPv4 RPC: failed to bind TCP port 6800 Exception: [SocketCore.cc:312] errorCode=1 Failed to bind a socket, cause: An attempt was made to access a socket in a way forbidden by its access permissions.

04/05 22:43:41 [ERROR] IPv6 RPC: failed to bind TCP port 6800 Exception: [SocketCore.cc:312] errorCode=1 Failed to bind a socket, cause: An attempt was made to access a socket in a way forbidden by its access permissions.

04/05 22:43:41 [ERROR] Exception caught Exception: [DownloadEngineFactory.cc:219] errorCode=1 Failed to setup RPC server.

Can you help me?