Connecting Ethereum nodes that are on different machines
<p>I am experimenting with Ethereum. I have successfully setup a private testnet via the instructions on the site. However, I am having trouble adding peers from different machines. On any node I create, the admin.nodeInfo.NodeUrl parameter is undefined. I have gotten the enode address by calling admin.nodeInfo and when I try the admin.addPeer("enode://address") command (with the public IP,) it returns true but the peers are not listed when calling admin.peers. </p>

<p>I read on another thread (<a href="https://stackoverflow.com/questions/33826018/in-ethereum-what-is-a-private-testnet-why-would-i-want-it-and-how-do-i-set-it">here</a>) that the private testnet is only local, but I am seeing plenty of documentation that suggests otherwise (<a href="https://www.ethereum.org/cli" rel="nofollow noreferrer">here</a> and <a href="https://github.com/ethereum/go-ethereum/wiki/Setting-up-private-network-or-local-cluster" rel="nofollow noreferrer">here</a>.) I have tried the second tutorial adding the command-line flags for custom networkid and genesis block.</p>

<p>Any advice would be much appreciated. Please let me know if I can provide more details.</p>