Re: How do I open up a specific port?

Yossu · ‎2017-05-11

I hope I picked the right model number above. The device web page calls it a WNDR3700v4, whereas the box says it's an N600. The sticker on the bottom of the box says WNDR3700-100UKS.

Anyway, I'm a software developer, and I want to use a deployment tool that uses port 8172. The hosting company who host our web sites told me I need to be able to telnet to an URL that uses that port.

Can anyone explain how I open up this port? I looked through the docs, but they don't seem to match what I see. I can't see anything about firewall rules.

Thanks for any help you can give.

w3wilkes · ‎2017-05-11

You might start reading the manual on page 83

http://www.downloads.netgear.com/files/GDC/WNDR3700V4/WNDR3700v4_UM_16Nov12.pdf

Yossu · ‎2017-05-14

Thanks for the reply. However, if I read this correctly, I shouldn't need to open the port. I'm trying to telnet to a remote machine. According to what I read the other day, the router doesn't block any outgoing traffic by default. According to the page you mentioned "Normally, your router ignores any inbound traffic that is not a response to your own outbound traffic" which means that if I start a telnet session, any inbound traffic in response to that should not be blocked. If so, then the fact that I can't telnet doesn't sound like the problem is the router blocking.

Does that make sense? Thanks again

TheEther · ‎2017-05-14

Correct. The router does not block any outgoing traffic. Make sure your can ping/traceroute/tracert to the destination to confirm that you can reach the destination.

Yossu · ‎2017-05-14

Thanks again. Not being a netowrk expert, I had to search to find how to ping or tracert to a specific port (seems you can't), and I came across this post. I tried that, and got the same result as when I tried the URL our hosting company gave with port 8172. Specifically, it sits there for a few minutes, then says "Connection to host lost."

This sounds like it's not the specific port that's the issue. As far as I understand, port 443 is an standard one for secure traffic, so presumably is open on my machine. I'm now completely lost as to what the problem could be.

Any ideas? Thanks again

TheEther · ‎2017-05-14

ping and tracert don't operate at the port level. They can help verify basic IP connectivity to the destination. If they are failing then there's no way for telnet to work.

You should try to tracert to the destination and see where it fails. If it fails anywhere except hop 1, then your router is not the problem.

Yossu · ‎2017-05-14

Thanks for the reply. Although I don't really understand the output, tracert is giving me lots of lines with various URLs at the end, which implies it is finding a route to the remote server...

  1    <1 ms    <1 ms    <1 ms  192.168.1.1
  2    14 ms    14 ms    14 ms  lo0.central10.pcn-bng01.plus.net [195.166.130.248]
  3    15 ms    15 ms    14 ms  411.be5.pcn-ir02.plus.net [84.93.253.71]
  4    15 ms    15 ms    14 ms  195.99.125.140
  5    15 ms    15 ms    15 ms  195.99.127.83
  6    15 ms    15 ms    15 ms  t2c3-et-7-1-0-0.uk-lon1.eu.bt.net [166.49.211.228]
  7    83 ms    83 ms    83 ms  ixp1-xe-11-3-1-0.us-nyc.eu.bt.net [166.49.208.169]
  8    83 ms    82 ms    83 ms  te-0-6-0-19-pe03.111eighthave.ny.ibone.comcast.net [75.149.228.161]
...

Do I take it from this that my router isn't the problem?

If so, do you have any idea what might be the problem? Thanks again.

TheEther · ‎2017-05-14

Those aren't URLs. They are domain names. For example, the domain name for this Netgear forum is community.netgear.com.

Anyway, you didn't show whether the tracert reached the destination. Did it?

Yossu · ‎2017-05-14

Ah, my mistake, thanks for the clarification. Here's the full output from tracert..

Tracing route to pixata-001-site11.itempurl.com [205.144.171.62]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.1.1
  2    14 ms    14 ms    14 ms  lo0.central10.pcn-bng01.plus.net [195.166.130.248]
  3    15 ms    15 ms    14 ms  411.be5.pcn-ir02.plus.net [84.93.253.71]
  4    15 ms    15 ms    14 ms  195.99.125.140
  5    15 ms    15 ms    15 ms  195.99.127.83
  6    15 ms    15 ms    15 ms  t2c3-et-7-1-0-0.uk-lon1.eu.bt.net [166.49.211.228]
  7    83 ms    83 ms    83 ms  ixp1-xe-11-3-1-0.us-nyc.eu.bt.net [166.49.208.169]
  8    83 ms    82 ms    83 ms  te-0-6-0-19-pe03.111eighthave.ny.ibone.comcast.net [75.149.228.161]
  9    84 ms    84 ms    84 ms  hu-1-4-0-0-cr02.newyork.ny.ibone.comcast.net [68.86.84.249]
 10    85 ms    86 ms    84 ms  be-10203-cr01.newark.nj.ibone.comcast.net [68.86.85.185]
 11    96 ms    95 ms    95 ms  be-10102-cr02.ashburn.va.ibone.comcast.net [68.86.85.161]
 12   108 ms   109 ms   110 ms  be-10114-cr02.56marietta.ga.ibone.comcast.net [68.86.85.10]
 13   128 ms   127 ms   127 ms  be-11424-cr02.dallas.tx.ibone.comcast.net [68.86.85.22]
 14   159 ms   159 ms   159 ms  be-11524-cr02.losangeles.ca.ibone.comcast.net [68.86.87.173]
 15   159 ms   158 ms   159 ms  be-11599-pe01.losangeles.ca.ibone.comcast.net [68.86.84.194]
 16   158 ms   158 ms   158 ms  po3.comcast.edge01.onewilshire.la.ca.sharktech.net [107.167.0.225]
 17     *        *        *     Request timed out.
 18   157 ms   157 ms   156 ms  customer.sharktech.net [107.167.4.70]
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21   156 ms   155 ms   155 ms  205-144-171-62.alchemy.net [205.144.171.62]

Trace complete.

What does that tell you? Thanks again.

TheEther · ‎2017-05-14

Ok, you can reach the destination. Are you specifically supposed to use telnet to connect to the site? And you are supposed to connect to port 8172?

If so, did you try telnet 205.144.171.62 8172? telnet is not secure, so it's a bit unusual to be using it these days.

Yossu · ‎2017-05-14

I'm a software / web site developer, and I want to use a deploy tool to deploy a web site to the hosting company's server. I couldn't get the tool to work, and they said I should try telnet to see if connectivity was the problem. As long as I couldn't telnet to the server, the tool wasn't going to work.

I have no idea if the tool uses telnet under the covers, or if this was just a way of seein I could connect.

I was trying telnet pixata-001-site11.itempurl.com 8172, because that's what they told me to try. However, I just tried using the IP address, and it did exactly the same thing. Sat there for a few minutes, then said "Connection to host lost."

What now? Thanks very much for all the help.

TheEther · ‎2017-05-14

It's doubtful that the deploy tool uses telnet. They're having you use telnet as a troubleshooting tool. If it can connect then that meants that the TCP connection was established. That's hugely important because it tells you that the network between you and them is working.

FWIW, I can connect to that site:

$ telnet pixata-001-site11.itempurl.com 8172
Trying 205.144.171.62...
Connected to pixata-001-site11.itempurl.com.
Escape character is '^]'.

Is this what you see? Then that means it's working.

Ask the company if they can help with troubleshooting. Tell them that you can ping their server but telnet to port 8172 fails. Ask them if their firewall could be blocking access from your IP address.

Yossu · ‎2017-05-14

They said they have tested it and can telnet to the server, so insist the problem is at my end. If I open a command window and try the telnet, it sits there doing nothing for a few mins, then the window goes blank and I get the "Connection to host lost" message I mentioned. I've never seen a message "Connected to pixata-001-site11.itempurl.com" like you did.

Where does this leave me?

Yossu · ‎2017-05-16

Any ideas?

TheEther · ‎2017-05-16

Remove your router and connect your PC directly to the modem. You may have to reboot your modem in order for your PC to get an IP address. Then retry telnet.

Yossu · ‎2017-05-16

Thanks for the idea. I'll have to wait until tonight to try that as I have another PC on the router that needs the connection during the day.

Yossu · ‎2017-06-19

Hello again,

Sorry for the delay in replying. I can only disconnect the router on a Sunday, and it's taken a couple of weeks to get a free Sunday!

Anyway, I tried plugging the PC directly into the modem, but couldn't get any connectivity at all. Not sur what I'm doing wrong (remember, I'm no network expert), but I couldn't work out how to get the PC to see the connection at all.

Any ideas? Thanks

w3wilkes · ‎2017-06-19

Sorry, I made a mistake. Thought you wanted to login the the router rather than the modem. You will need to find out how to log in to the modem from the modem manufacturer. Then you can see if the modem does anything with ports or if it just runs in bridge mode. If in bridge mode the ports should all be controlled from your router.

Yossu · ‎2017-06-19

I'm not really sure what I want to do! I thought the idea was to try and rule out the router as a potential probelm, so I plugged the PC into the modem, thinking that if that worked, it would identify the router as the problem.

Please can you explain what I should do now, as I'm a bit confused. Words of one syllable please 🙂

Thanks again

w3wilkes · ‎2017-06-19

Does your router have your ISP credentials (login ID and password) for your internet access? If so, this would tell me that your modem is in bridge mode and plugging your PC directly into the modem may not work. Is the modem provided by your ISP? If so, you should contact your ISP to find out if they can give you instructions for how to connect a PC directly to the modem and get on the internet.

Yossu · ‎2017-06-19

Yes, I needed to enter my credentials when I set up the router. The modem is the one the ISP supplied (I'm with PlusNet, and they supplied a BT OpenReach modem), which could explain it.

I'll try asking them and see what they say.

Thanks again.

w3wilkes · ‎2017-06-19

Sounds like the modem runs in bridge mode then. That being said I'd find it hard to believe that the modem is blocking any ports. If your ISP says they don't block any ports then it must be your router. If you open a port on your router you can test it using the Shields Up site.

https://www.grc.com/x/ne.dll?bh0bkyd2

When you open the port use shields up to probe the port you opened. Shields up will show you the status of the port.

Yossu · ‎2017-06-20

Right, I used that site to check port 8172, and it said it was in stealth mode. This forum won't let me add a picture, so you'll have to believe me!

I went to the router's web page, clicked the Advanced tab at the top, then went to WPS Wizard -> Security -> Block Services, and added an entry for port 8172. When I tried to telnet again, I got a message Connecting To pixata-001-site11.itempurl.com... which was new, as until now the command window went blank, and then after a minute or so, it added Could not open connection to the host, on port 8172: Connect failed.

This makes sense, as I added a rule to block the port. However, it implies that the router was not blocking the port before I added the rule.

At this stage, I'm stuck again! You mentioned opening the port. How do I do that? I can only see an option to block services, nothing for opening them.

Thanks again.

Yossu · ‎2017-06-20

Just tried something else. I went to WPS Wizard -> Security -> Port Forwarding / Port Triggering and added a custom rule for port 8172 to forward to my main PC, but this didn't make any difference. I got the same blank command window when I tried to use telnet.

w3wilkes · ‎2017-06-20

I'm really out of ideas...

Do you have the most recent firmware installed on the router (page 63 of the manual)

Do you have your PC set to have a reserved address (page 42 of the manual) so that it always has the same IP address when attached to your router?

If you have shut off UPnP (page 92 in the manual) then reboot the router. Then manually opened port 8172 to the IP address of your PC (page 84 of the manual), the port should show as open to ShieldsUp. If the port doesn't show open then either your ISP is blocking it or the router isn't working.

Link to manual is

http://www.downloads.netgear.com/files/GDC/WNDR3700V4/WNDR3700v4_UM_16Nov12.pdf