Resolve IP to HOSTNAME kinda

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Resolve IP to HOSTNAME kinda

tek

112 posts

Master Geek
+1 received by user: 8

ID Verified

#195649 28-Apr-2016 11:42

Ok, so I'll try explain this as best I can with the limited time I have to make this post...

I have a CommandFusion LAN Bridge that sends me push notifications for various events, but it only supports entering an IP for a push service. Recently Growl changed the way they do things and they require you to use their host-name which is api.prowlapp.com. If I resolve that into their IP using nslookup, I get: 54.225.207.133, 23.21.249.174 and 23.23.183.201. If I use any of those in the IP field, nothing gets pushed. After talking to their support they said we must use the host-name api.prowlapp.com, and that the resolved IPs will change from time to time.

So... Is there any way either in my router (Draytek Vigor 2120) or an app I could run on my Windows Server to allow me to resolve an IP I put in my LAN Bridge to prowls host-name api.prowlapp.com?

Cheers for any help and hope it makes some sense

-tek

BigPipe 1000/500 - East Tamaki, Auckland
BigPipe Speedtest

joeloconnor.nz

1 | 2

4016 posts

Uber Geek
+1 received by user: 1852

ID Verified

Trusted

Lifetime subscriber

#1543310 28-Apr-2016 11:47

I've never heard of such a beast.

You might have to rework your notifications.... if you are testing to ensure a LAN Bridge is up, perhaps a ping tester (such as EMCO Ping Monitor) that sends an email if it does not get a result and have the Growl service receive the email and generate a push notification from this? I've never used or even heard of Growl/Prowl before, but it looks useful.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

sbiddle

30853 posts

Uber Geek
+1 received by user: 9996

Retired Mod

Trusted

Biddle Corp

Lifetime subscriber

#1543312 28-Apr-2016 11:48

What device on your network is handling DNS? Your router or server?

Dynamic

4016 posts

Uber Geek
+1 received by user: 1852

ID Verified

Trusted

Lifetime subscriber

#1543313 28-Apr-2016 11:48

Or hit up CommandFusion for a firmware update to support DNS.

Or hit up Growl to keep their legacy systems going as you will not be alone.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

tek

112 posts

Master Geek
+1 received by user: 8

ID Verified

#1543325 28-Apr-2016 12:08

@sbiddle my router is. Though I have been tempted to build a pfsense router if that would do what I'm wanting.. Or could I run a secondary DNS in Hyper-V on my server to do what I need? And just point the LAN bridge to that.

@Dynamic Growl pretty much said no :( and guided me to google how to resolve a IP to a hostname in my router, which doesn't seem to be a thing on most routers.

BigPipe 1000/500 - East Tamaki, Auckland
BigPipe Speedtest

joeloconnor.nz

wasabi2k

2102 posts

Uber Geek
+1 received by user: 860

#1543329 28-Apr-2016 12:12

Your symptom does not make sense.

In general, when you use a DNS name with an application to do anything networking, the flow would be:

1. Lookup Name

2. Send to IP Address

With the exception being proxy type traffic, where name resolution doesn't happen at the client (usually).

If your app isn't working, potentially it is encoding the name in the request somehow and that is being rejected, but at a networking level what you are trying to do does not make any sense. By the time a packet is leaving your router it is being sent from an IP, to an IP.

Sounds like you have 2 issues:

1. Your app doesn't like sending to an IP address and

2. The IPs for your endpoint will change from time to time.

tek

112 posts

Master Geek
+1 received by user: 8

ID Verified

#1543348 28-Apr-2016 12:33

Okay, right that's what I thought. I've just been told by a few people when researching this that it is possible. I just don't know enough about networking to know what to search for...
It used to work with an IP address before Growl changed their setup, but I guess now my only option is to wait for CommandFusion to provide an update for the LAN Bridge?

Also, would there be any reason why using one of the resolved IP's doesn't work? I've tried all 3 to no sucess.

Cheers guys :)

BigPipe 1000/500 - East Tamaki, Auckland
BigPipe Speedtest

joeloconnor.nz

Lenovo

Shop now for Lenovo laptops and other devices (affiliate link).

BlackHand

135 posts

Master Geek
+1 received by user: 19

#1543355 28-Apr-2016 12:45

Also, would there be any reason why using one of the resolved IP's doesn't work? I've tried all 3 to no sucess.

Since their web server uses host headers, so you need to pass the hostname

A sacrifice of blood and bone, A bridge for you to cross, You will emerge a shadow ~ The Black Hand

sqishy

530 posts

Ultimate Geek
+1 received by user: 193

#1544685 30-Apr-2016 23:35

Hi, I'm not sure whats you mean but you can resolve using Hosts file in C:\Windows\System32\drivers\etc.

Check the use of this, Google is your friend.

Dynamic

4016 posts

Uber Geek
+1 received by user: 1852

ID Verified

Trusted

Lifetime subscriber

#1544706 1-May-2016 08:22

sqishy:

Hi, I'm not sure whats you mean but you can resolve using Hosts file in C:\Windows\System32\drivers\etc.

Are you sure? I've been using the HOSTS file for the last 20 years to have an application look for a server by name and the HOSTS file tells it the IP address to use. The OP wants to do the opposite.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

ArcticSilver

731 posts

Ultimate Geek
+1 received by user: 148

#1544819 1-May-2016 12:41

tek:

Okay, right that's what I thought. I've just been told by a few people when researching this that it is possible. I just don't know enough about networking to know what to search for...
It used to work with an IP address before Growl changed their setup, but I guess now my only option is to wait for CommandFusion to provide an update for the LAN Bridge?

Also, would there be any reason why using one of the resolved IP's doesn't work? I've tried all 3 to no sucess.

Cheers guys :)

You say you did a NSLookup for the 3 IP addresses? If this is the case, that would be why they do not work!

A NS Lookup is a "Name Server Lookup", this will get you the IP addresses of the authoritative name servers in use for the domain, but not what you are after which is the IP address of the domain name.

The easiest way to find what you are after is to do a ping of the domain name via cmd (type the following in cmd - "ping api.prowlapp.com") and at the top it will resolve the IP address to ping. Use the IP address resolved by this command.

If possible you should always use the host name as they may change servers/the location of their hosted service, if this is the case you will have to go through this process again and manually change the IP address.

BarTender

3629 posts

Uber Geek
+1 received by user: 2572

ID Verified

Trusted

Lifetime subscriber

#1544832 1-May-2016 12:52

If you put HAProxy or similar reverse proxy in between you should be able to sort it.

New World

Shop on-line at New World now for your groceries (affiliate link).

tek

112 posts

Master Geek
+1 received by user: 8

ID Verified

#1544949 1-May-2016 17:59

ArcticSilver:

tek:

Okay, right that's what I thought. I've just been told by a few people when researching this that it is possible. I just don't know enough about networking to know what to search for...
It used to work with an IP address before Growl changed their setup, but I guess now my only option is to wait for CommandFusion to provide an update for the LAN Bridge?

Also, would there be any reason why using one of the resolved IP's doesn't work? I've tried all 3 to no sucess.

Cheers guys :)

You say you did a NSLookup for the 3 IP addresses? If this is the case, that would be why they do not work!

A NS Lookup is a "Name Server Lookup", this will get you the IP addresses of the authoritative name servers in use for the domain, but not what you are after which is the IP address of the domain name.

The easiest way to find what you are after is to do a ping of the domain name via cmd (type the following in cmd - "ping api.prowlapp.com") and at the top it will resolve the IP address to ping. Use the IP address resolved by this command.

If possible you should always use the host name as they may change servers/the location of their hosted service, if this is the case you will have to go through this process again and manually change the IP address.

Now I feel dumb haha! I know NSLookup finds the nameservers, but for some reason I still used it. Ping would have been the correct tool to use -.- Though I just did a ping and it gave me the same IP as one of the nameservers, though I'll try it again.

BarTender: If you put HAProxy or similar reverse proxy in between you should be able to sort it.

I will look into HAProxy :) thanks

BigPipe 1000/500 - East Tamaki, Auckland
BigPipe Speedtest

joeloconnor.nz

fe31nz

1294 posts

Uber Geek
+1 received by user: 423

#1544950 1-May-2016 18:00

ArcticSilver:

tek:

Okay, right that's what I thought. I've just been told by a few people when researching this that it is possible. I just don't know enough about networking to know what to search for...
It used to work with an IP address before Growl changed their setup, but I guess now my only option is to wait for CommandFusion to provide an update for the LAN Bridge?

Also, would there be any reason why using one of the resolved IP's doesn't work? I've tried all 3 to no sucess.

Cheers guys :)

You say you did a NSLookup for the 3 IP addresses? If this is the case, that would be why they do not work!

A NS Lookup is a "Name Server Lookup", this will get you the IP addresses of the authoritative name servers in use for the domain, but not what you are after which is the IP address of the domain name.

The easiest way to find what you are after is to do a ping of the domain name via cmd (type the following in cmd - "ping api.prowlapp.com") and at the top it will resolve the IP address to ping. Use the IP address resolved by this command.

If possible you should always use the host name as they may change servers/the location of their hosted service, if this is the case you will have to go through this process again and manually change the IP address.

No, you are wrong about the three IP addresses. Many web servers are distributed over multiple server boxes, and therefore have multiple IP addresses. Not infrequently, such web server boxes are at different physical sites, so that when the Internet has a problem at one location, the other sites will still respond. When you use a web browser to access a domain name that has multiple IP addresses, it will do a DNS lookup and use the first of the returned addresses. If that fails to respond, if it is a good web browser, it will try again with the next address. In order to distribute the traffic amoungst the mutiple IP addresses, and also to help with browsers that only ever use the first IP address that was returned, most DNS servers will produce the IP addresses in a different order each time the same DNS lookup is done. Here is what multiple lookups did from my personal DNS server (Bind 9.10.1 on Windows 7):

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.21.249.174
          54.225.207.133
          23.23.183.201

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.23.183.201
          23.21.249.174
          54.225.207.133

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.23.183.201
          23.21.249.174
          54.225.207.133

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 54.225.207.133
          23.21.249.174
          23.23.183.201

The problem with accessing the api.prowlapp.com using only its IP address is a different matter altogether. Many web servers, especially those that provide commercial hosting of many small (and cheap) web sites, do not provides a separate IP address for each site they host. Instead, they use the same IP addresses, but differentiate the sites using the site name provided in the HTTP(S) messages received. So if you manually look up the IP address for any of those sites, you will get the same set of IP addresses. And if you then use only one of those IP addresses to access the site from your browser (or other software), it will not work because the HTTP(S) request will only contain the IP address of the site, but not its name, and the web server will not know which of the many sites it hosts is the one being requested.

ArcticSilver

731 posts

Ultimate Geek
+1 received by user: 148

#1545011 1-May-2016 20:17

fe31nz:

No, you are wrong about the three IP addresses. Many web servers are distributed over multiple server boxes, and therefore have multiple IP addresses. Not infrequently, such web server boxes are at different physical sites, so that when the Internet has a problem at one location, the other sites will still respond. When you use a web browser to access a domain name that has multiple IP addresses, it will do a DNS lookup and use the first of the returned addresses. If that fails to respond, if it is a good web browser, it will try again with the next address. In order to distribute the traffic amoungst the mutiple IP addresses, and also to help with browsers that only ever use the first IP address that was returned, most DNS servers will produce the IP addresses in a different order each time the same DNS lookup is done. Here is what multiple lookups did from my personal DNS server (Bind 9.10.1 on Windows 7):

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.21.249.174
          54.225.207.133
          23.23.183.201

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.23.183.201
          23.21.249.174
          54.225.207.133

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 23.23.183.201
          23.21.249.174
          54.225.207.133

[P:\]nslookup api.prowlapp.com
Server: savaidhg.6.jsw.gen.nz
Address: 2406:e001:1:2802::2

Non-authoritative answer:
Name:    api.prowlapp.com
Addresses: 54.225.207.133
          23.21.249.174
          23.23.183.201

The problem with accessing the api.prowlapp.com using only its IP address is a different matter altogether. Many web servers, especially those that provide commercial hosting of many small (and cheap) web sites, do not provides a separate IP address for each site they host. Instead, they use the same IP addresses, but differentiate the sites using the site name provided in the HTTP(S) messages received. So if you manually look up the IP address for any of those sites, you will get the same set of IP addresses. And if you then use only one of those IP addresses to access the site from your browser (or other software), it will not work because the HTTP(S) request will only contain the IP address of the site, but not its name, and the web server will not know which of the many sites it hosts is the one being requested.

Hi fe31nz,

I think you've confused a particular name server setup with the way NSLookup works and what it does.

You cannot have multiple IP addresses in the 1 A record (domain record). What you can however have is multiple name servers with different records.

Generally speaking, you will have multiple clustered name servers (for redundancy) which have the same record between them and hence when you do a NSLookup you get multiple addresses as there are multiple name servers that can tell you where the server for that domain is located.

The name server that is used is the one with the lowest metric that is responsive, hence you can go down the list for redundancy (for the name server, not the host).

In the case of accessing via a domain vs IP address, this could be a problem depending on how the API is hosted (as you have mentioned), however from what has been previously said it is highly likely this is not the case and that an IP address could work. This however is some thing that only the host will know.

jnimmo

1098 posts

Uber Geek
+1 received by user: 255

#1545038 1-May-2016 21:23

Does the LAN Bridge let you do email notifications?
I use Boxcar for push notifications from a building management system which can send notifications via email/SMTP

They give you a secret address @bxc.io which gets pushed to iOS or Android apps

May be an alternative if no joy with Growl

1 | 2