how to open closed port?

you need to discuss with the developer or determine if a 3rd party is blocking your ability, that could be software, it could be your ISP not wanting you to use software primarily for pirating software, audio and video because it's illegal to do so, but OS X does not block ports and the firewall is by application only, and Transmission has already had it's distort hacked and was modified to be malware a few months ago.

You are the one who asked how to open a closed port. I just asked which port.

Check your router settings. An external server/device can not see your computer on a local network if it is behind a router. The router will forward requests on the requested port to your computer. It remains that ports are not closed on your computer. You have installed some third party software to block ports or your router is blocking ports or your ISP is blocking ports.

I am not a fan of torrents and do not use it so can not help any further.

You don't seem to understand, it's not being blocked by the Airport Extreme. It's not being blocked by your Mac. It's being blocked by the router supplied by your ISP or something on their network. Unless, of course, you've managed to install one of the numerous Mac "cleanup" or virus protections applications that are largely crap and will do more harm than good... or managed to install malware along with some of the presumably pirated content you're downloading with Transmission.

Apologies if that's not what you're using it for, but I find it highly unlikely that it's being used for anything legitimate.

Hello again tag,

But why do you keep punching it? If you have it set to automatically randomize, just start it up and let it run. If you want to change the port at some point, try clicking the button just once. It may take a few moments to re-establish connectivity.

Hello !

I can give some method how to check open ports but the question you asked how to open closed port you have to ask your internet service provider .

So , open system preferences & in network find your IP address that you need to test .

Then , open network utility via spotlight , enter your IP address & check the box only test ports between and fill up the fields & click on scan , if you see absolutely nothing comes up but you know an IP is active with open services , either the computer isn't broadcasting or the recipient machine is rejecting all requests or perhaps a strong firewall is configured . This makes network utility port scanner an excellent way to quickly check security & test out potential vulnerabilities on active services .

If you don't see an open port TCP listing , the port might be blocked or unreachable , check the security software thats installed on the computer you're testing .

And , if you are concerned about securities on network you can go to security & privacy - check firewall , or can use block all incoming connections , stealth mode .

tag Gallagher, the important point you may be missing is shown in the image dialabrain posted, the checkbox to allow 'NAT traversal'.

What that means is Transmission will ask your router to open a port so that data from the outside can see your torrent client on the Mac. Your router needs to have one of those features enabled.

Ports in the context that Transmission uses are on the outside of your network, so you must check the router settings.

The default GRC.com test will not help you as it scans below the range that transmission uses, you need to use the custom port lookup…

https://www.grc.com/x/ne.dll?rh1dkyd2(the site is fugly but is useful)

In the blue table enter your port(s) that Transmission is trying to open & click 'Custom Port Probe' it will list the status as seen from the internet.

It might be Sierra that is falling to allow it to work but you need to boot into an older OS to confirm that - do you have a bootable backup of the prior OS?

Also Transmission does not require open ports to work, it just likes them to allow for better peer sharing, you can still download without them.

tag Gallagher wrote:

Tranmission has a RANDOMIZE button to rest the port. It comes up with a new 5-digit number each time and says that port is closed. Eventually it says "Port check site is down." I don't know what that means.

Finally has it occurred to you that it might just be that the issue is with the tool that Transmission uses to test the port - it has to try accessing from outside your network, if their site is down, the test will fail…

tag Gallagher wrote:

No, Apple's Airport Utility for Airport Extreme does not have any settings that mention "port."

The settings you are looking for are for NAT-PMP or UPnP.

https://en.wikipedia.org/wiki/NAT_Port_Mapping_Protocol

https://en.wikipedia.org/wiki/Universal_Plug_and_Play

I don't have an Airport router to check but many routers enable them by default these days.

Network Utility is useless to you - it tells you about ports on your Mac. You need to look at the ports from the OUTSIDE of your network. That is why I explained how to use GRC.com's port checker.

You can also use the guide on the Transmission wiki…

https://trac.transmissionbt.com/wiki/PortForwardingGuide

Which suggests you use http://www.canyouseeme.org/ to check the port too.

Hello again tag,

I can explain some of this stuff.

All network services that listen for incoming connections need to use a well-known port so that other machines can find them. When you make an outgoing connection, it doesn't matter. You just pick a random port. But in order for someone else to find you, you need to listen on port 80 (for a web server) and your clients will look for your port 80.

Transmission works like this too. But it is software non grata so people want to shut it down. In response, it gets a little more clever by listening on random ports and then using its outgoing connection to tell clients what that port really is.

There is some magic and extra work involved to make that happen. That is where the "port check site" comes in. There must be some other server or servers that check your randomized server to see if it is working so they can tell other clients what port you are using.

Keep in mind that all of the above is assuming that your computer is directly connected to the internet. That is rare. In most cases, there is some intermediary between you and the open internet. That intermediary is usually your WiFi router. Some older DSL modems would use a different kind of connection and put you right out there, but you aren't likely to see those anymore. So, that "port" you are using actually has to be open on your WiFi router. Then your WiFi router need to relay messages back to your machine on that same port. The NAT-PMP or UPnP settings that Drew mentioned are what tries to make that work.

You mentioned that "Universal Plug n' Play Internet Exposure Test which said my equipment didn't respond, which is good news". That may not be good news. If you are trying to open a port for listening, you probably do want to have your equipment respond.

And to make things even more complicated, BitTorrent is a funky, but completely legal, networking protocol called UDP. So much of what I said about "listening" above doesn't even apply. Take another look at Drew's responses regarding http://www.canyouseeme.org/.

I just tried Transmission on Sierra and I can't see any difference. It runs fine. You probably don't have the same wireless router and ISP that I have though. Your results could be different. Maybe Sierra is not talking properly to your wireless router.

Can you tell us what wireless router you are using? It that what is making your internet connection too? Did you get it from your ISP? Any equipment your ISP gives you is junk. Mine is junk. Originally my WiFi was actually slower than my internet. I went out and bought a $30 wireless router, disabled the Wifi on my ISP device, and connected them in bridge mode. Now I get the correct speeds. My bit torrent works too. I suspect that is where your problem lies.