Bitcoin Forum

Is there any benefits to forwarding port 8333TCP for using the Bitcoin client or will UPnP do just as good.  Also if there is a benefit how can you forward the ports for more than one PC on your home network as I can only allocate a port to one device on my router.

Port forwarding is not necessary to run Bitcoin. The only reason to forward the port would be to have more than 8 connections. If you want to do port-forwarding for more than one box on your home network, set each Bitcoin instance to use a different port (in bitcoin.conf) and forward each port to the specific device.

Is there any benefits to having more than 8 peer connections?

Faster transactions confirmations? Nah, I guess not.

Maybe a better chance of picking up double-spends?

UPNP is how software running on your computer talks to your router to establish port forwarding.  If UPNP works, you don't need to forward the port manually too.

There is no real benefit to you in allowing incoming connections, but the network needs some amount of connectable ports so that new nodes can get online.  I don't believe that there is a shortage of incoming ports on the network at the moment, so don't feel too bad if you can't get port forwarding set up.

So no benefits if you got 20 connections compared to say 8 connections ?

What about solo mining ? I think latency and connections do affect that so it can matter but I am not sure ...

Having a computer behind NAT that doesn't accept incoming connections is like downloading a torrent while blocking its uploads. If nobody took the time to set port forwarding, Bitcoin wouldn't be as responsive.

While miners create transaction blocks, the P2P network does the work of propagating the blocks to other nodes. In addition the transaction messages when someone presses "send coins" are relayed via the p2p network to other nodes (some of which will be miners). If you only have a few connections, you are relying to just a few p2p peers to relay your transactions to others; if you are highly connected, than many more peers get your transactions directly from you. If you complain about slow block downloading, remember the blockchain comes from other peers; if half of the peers are a black hole, it takes longer to download.

It is also possible for bad guys to create bad nodes that do odd things on the p2p network, the more good nodes there are with full connectivity, the better.

As Bitcoin runs on port 8333, you can only forward this port to one computer inside your network. More than one computer running Bitcoin with uPnP, wanting the same port, will likely confuse your router. Additional clients inside your network should connect to your main Bitcoin using the connect=IP.IP.IP.IP config option; they will sync much faster and your bandwidth use will be less.

- 55 active connections to Bitcoin network

I've set up port-forwading and have 54 connections.

All nice and well but how does this affect solo mining folks ?

Lowered chances of finding a block due to lower connections ?

You won't have a lower chance of finding a block, but publishing your block find will be hindered. If someone else found a block with a similar difficulty hash at the same time as you, it may be the miner who got their block distributed more quickly that wins the block generate.

Bitcoin does not require any specific port.  If you use UPNP, you will likely get a random port assignment, and if you plan to run multiple nodes on a single IP, then you will need to use other ports.  It works just fine, and you can get incoming connections regardless of the ports you use or what you have to do to get them.

The whole point of having a network is that it isn't necessary to connect to every node.  8 connections is "enough" for just about anyone.  More is better, sorta, maybe, a little, but not worth losing sleep over.  If you are mining, you would be better off with 8 connections to the 8 biggest pools than you would be with 100 connections to random other nodes.

One thing to make note of... if you port forward, you'll be using up more bandwidth (from relaying the blockchain to more users).  For some people, this is completely unimportant.  For others (such as those in Australia), it can push them over their monthly limitations.

While I've got a 40Mbit/10Mbit VDSL2 FTTC connection that is getting upgraded to 80Mbit/20Mbit connection this year with unlimited bandwidth (tho I think they'd moan after 100GB).  So might as well forward my ports to help the network?

It's completely up to you.  If you take more of the load off of other people, then it could help them.