首先啟動服務

		
neo@netkiller ~ % geth --networkid 123456 --rpc --rpcaddr="0.0.0.0" --rpccorsdomain "*" --nodiscover 
INFO [02-01|23:35:12] Starting peer-to-peer node               instance=Geth/v1.8.8-stable-4bb3c89d/linux-amd64/go1.10.2	
INFO [02-01|23:35:12] Allocated cache and file handles         database=/home/neo/.ethereum/geth/chaindata cache=128 handles=1024
INFO [02-01|23:35:12] Initialised chain configuration          config="{ChainID: 15 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Byzantium: <nil> Engine: unknown}"
INFO [02-01|23:35:12] Disk storage enabled for ethash caches   dir=/home/neo/.ethereum/geth/ethash count=3
INFO [02-01|23:35:12] Disk storage enabled for ethash DAGs     dir=/home/neo/.ethash               count=2
INFO [02-01|23:35:12] Initialising Ethereum protocol           versions="[63 62]" network=123456
INFO [02-01|23:35:12] Loaded most recent local header          number=719 hash=61330b…82786e td=108754979
INFO [02-01|23:35:12] Loaded most recent local full block      number=719 hash=61330b…82786e td=108754979
INFO [02-01|23:35:12] Loaded most recent local fast block      number=719 hash=61330b…82786e td=108754979
INFO [02-01|23:35:12] Loaded local transaction journal         transactions=0 dropped=0
INFO [02-01|23:35:12] Regenerated local transaction journal    transactions=0 accounts=0
WARN [02-01|23:35:12] Blockchain not empty, fast sync disabled 
INFO [02-01|23:35:12] Starting P2P networking 
INFO [02-01|23:35:12] RLPx listener up                         self="enode://9f6490ffb5236f2ddc5710ae73d47c740e0a3644bbd2d67029cf4a6c4693d2f470b642fd2cc3507f7e851df60aaeb730a1270b7a477f91ec5b6b17a8a4b40527@[::]:30303?discport=0"
INFO [02-01|23:35:12] IPC endpoint opened: /home/neo/.ethereum/geth.ipc 
INFO [02-01|23:35:12] HTTP endpoint opened: http://0.0.0.0:8545 
INFO [02-01|23:35:15] Mapped network port                      proto=tcp extport=30303 intport=30303 interface="UPNP IGDv1-IP1"		
		
		

Web3j 將使用這個地址連接 HTTP endpoint opened: http://your_ip_address:8545