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IP Addresses

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IP Addresses was created by dmcdona

Folks - I'm installing my remote observatory control software and am having some problems figuring out IP addresses.

I have a DSL modem connected to the DSL line. This in turn is connected to a router. One networked PC connected to the router is running the observatory software (which includes web and ftp servers) .

I want to be able to give someone an IP address which they can type into a browser then logon to the observatory pc.

I can find the WAN ip (whatsmyip.com) address OK and I have configured the router to allow port forwarding to the observatory pc.

But it still ain't working.

Any hints on what I'm doing wrong would be helpful...

Cheers
Dave
15 years 8 months ago #46052

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Replied by voyager on topic Re: IP Addresses

Folks - I'm installing my remote observatory control software and am having some problems figuring out IP addresses.

I have a DSL modem connected to the DSL line. This in turn is connected to a router. One networked PC connected to the router is running the observatory software (which includes web and ftp servers) .

I want to be able to give someone an IP address which they can type into a browser then logon to the observatory pc.

I can find the WAN ip (whatsmyip.com) address OK and I have configured the router to allow port forwarding to the observatory pc.

But it still ain't working.

Any hints on what I'm doing wrong would be helpful...

Cheers
Dave


You're stepping into a mine field here! You need to check with your ISP whether or not you have a static IP. If it's not static you'll have to re-check the address each time you give it out.

Internally how are you dealing with IP addresses? Are you letting your router act as a DHCP server or are you manually assigning private IP addresses? If you're using DHCP you'll have to manually assign the one in the observatory regardless. It will need to be hard-coded with the correct gateway and netmask and you'll have to pick an IP that is in the right subnet but outside the range the DHCP server assignes in. Then you are ready to set up your port-forwarding to the observatory.

Now, it has to be said that some protocols don't deal well with port forwarding. It simply may not be possible to make this work through a NAT router (like effectively all broadband routers are).

Good luck with it!

P.S. feel free to skype me some time for a chat about this.

Bart.
My Home Page - www.bartbusschots.ie
15 years 8 months ago #46054

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Replied by albertw on topic Re: IP Addresses

I can find the WAN ip (whatsmyip.com) address OK and I have configured the router to allow port forwarding to the observatory pc.

But it still ain't working.


That sounds like it should work. how are you testing it? If you are testing it inside your own network then it may fail due to routing problems.
Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/
15 years 8 months ago #46056

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Replied by dmcdona on topic Re: IP Addresses

You're stepping into a mine field here!


You bet!

Unfortunaelty, I've yet to reinstall skype after the crash a few weeks back.

OK - my public IP address is dynamic (and that's fine - I understand this). But the issue seems to be that my public IP address is that of my DSL modem.

The DSL modem is connected to the Router which has its own private IP address (it also issues a static IP to the observatory PC). The observatory PC is setup in port-forwarding.

What seems to be confusing matters is my provider assigned IP address is assigned to the DSL modem (currently 78.16.26.12) - but the person who wants to connect to the observatory needs the router's ip address - right? or wrong?

Is the fact that I have a DSL moem conncted to a router complicating things? If so, what can I do to fix it (buy a better modem/router?)

Cheers
Dave
15 years 8 months ago #46058

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Replied by voyager on topic Re: IP Addresses

You're stepping into a mine field here!


You bet!

Unfortunaelty, I've yet to reinstall skype after the crash a few weeks back.

OK - my public IP address is dynamic (and that's fine - I understand this). But the issue seems to be that my public IP address is that of my DSL modem.

The DSL modem is connected to the Router which has its own private IP address (it also issues a static IP to the observatory PC). The observatory PC is setup in port-forwarding.

What seems to be confusing matters is my provider assigned IP address is assigned to the DSL modem (currently 78.16.26.12) - but the person who wants to connect to the observatory needs the router's ip address - right? or wrong?

Is the fact that I have a DSL moem conncted to a router complicating things? If so, what can I do to fix it (buy a better modem/router?)

Cheers
Dave


Hi Dave,

What do you mean by "router" and what do you mean by "modem", are they the same device?

The normal situation is that your modem and router are one box. Like all routers this one box has two IP addresses, an outside address (your public one), and an inside address, also a private IP (usually 192.168.1.1).

What happens inside this magic box is that between the internal and the external interface Network Address Translation happens. This means that all packets destined for the outside world get stripped open, get their private address removed and the router's public address stuck in instead. In effect all machines inside your network appear to be your public address. This is fine for connections initiated from inside the LAN, this can't work for connections coming in from outside. "I have a packet for port 80 on some machine ... aaaah .... which one?" That's where port-forwarding comes in. It tells NAT that an incoming connection on port X should be translated to Y private IP address.

However, some protocols are wrapped inside TCP-IP. When NAT does network address translation it ONLY translated the outter TCP-IP layer, not the wrapped protocol. So, the packet arrives at the right machine, the TCP/IP stuff gets stripped off and then the result gets handed to the program in question. If the program then checks the destination address against it's address it will see a miss-match and will probably throw away the packet. Protocols like this are said not to be able to traverse a NAT router. If this is the case here you are hosed. Nothing you can do.

Were I to be you I'd start with a very simple test. I's install an apache web server on the observatory machine, make it run on port 8080, port-forward port 8080 to that mahcine and then get a friend from outside to see if they can hit your web server. If they can your setup is right. If they can't it's not. You won't be able to test this from inside in all possability because you are on the wrong side of the NAT router so routing funnyness will probably occour as Al said.

Bart.
My Home Page - www.bartbusschots.ie
15 years 8 months ago #46060

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Replied by albertw on topic Re: IP Addresses

You're stepping into a mine field here!


You bet!

Unfortunaelty, I've yet to reinstall skype after the crash a few weeks back.

OK - my public IP address is dynamic (and that's fine - I understand this). But the issue seems to be that my public IP address is that of my DSL modem.


Have a look at www.dyndns.com it gives you a hostname that shifts as your IP address does. Handy for giving people access to your home network, without having to mail them IP addresses the whole time.

The DSL modem is connected to the Router which has its own private IP address (it also issues a static IP to the observatory PC). The observatory PC is setup in port-forwarding.

What seems to be confusing matters is my provider assigned IP address is assigned to the DSL modem (currently 78.16.26.12) - but the person who wants to connect to the observatory needs the router's ip address - right? or wrong?

Is the fact that I have a DSL moem conncted to a router complicating things? If so, what can I do to fix it (buy a better modem/router?)


Your modem will need to know where to send the packets. On my modem I can list the port (80 for http) I want forwarded and the destination in my network (the private IP address of your machine) I want it to be forwarded to.

So a user connects to 78.16.26.12 . The modem should see that it should forward that request to your PC. They don't need the IP of your router.
Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/
15 years 8 months ago #46061

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  • dmcdona
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Replied by dmcdona on topic Re: IP Addresses

The DSL modem and Router are two seperate boxes. The modem is connected to the router by an ethernet or ethernet-like cable.

As it happens, the IP address of the modem has just changed to 194.125.105.23. When I put this IP address in *my* browser, it opens up the logon dialogue for the modem. Perhaps this is where I'm getting confused - I'm seeing one thing, but folks outside might see something else.

So, the DSL model has a dynamic address (currently as above). The Router has a private address of 192.168.1.33

The networked observatory PC has a *static* private address of 10.10.10.103. Other PC's on the network are DHCP assigned.

The router also has port forwarding setup for 10.10.10.103 (on a non-standard port - I'm not telling).

ACP - the observatory software, runs on the observatory PC. It has a web and FTP server. Included in the package is DDNS service from www.no-ip.com/. The address I have been given is www.j65.my-sky.com. That makes the dynamic IP address a non-issue I hope. This must be working because it just figured out the IP address had been (dynamically) changed.

Both the modem and the router have configuration pages (and pages and pages....). Perhaps I've got some settings wrong...

Anyone getting an "aha!" moment?

Cheers

Dave
15 years 8 months ago #46062

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Replied by voyager on topic Re: IP Addresses

OK, alarm bells ringing here.

if your router is 192.168.1.33 then 10.10.10.103 is not in the same subnet. That is bound to cause problems unless you have some above-normal routing going on in your house. I's strongly recommend moving the static address for the observatory into the same subnet as 192.168.1.33, say, the very last address in the range, 192.168.1.254.

Bart.
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15 years 8 months ago #46063

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Replied by voyager on topic Re: IP Addresses

Actually, to save me making assumptions, can you show me the output of the command:

ipconfig/all

on a working DHCP assigned machine inside your network.

Bart.
My Home Page - www.bartbusschots.ie
15 years 8 months ago #46064

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Replied by dmcdona on topic Re: IP Addresses

D:\Documents and Settings\Dave>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : jupiter
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Home Office:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/100+ Management Adapter
Physical Address. . . . . . . . . : 00-D0-B7-E5-2C-09
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.10.10.102
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.10.10.1
DHCP Server . . . . . . . . . . . : 10.10.10.1
DNS Servers . . . . . . . . . . . : 10.10.10.1
Lease Obtained. . . . . . . . . . : 18 May 2007 12:31:14
Lease Expires . . . . . . . . . . : 25 May 2007 12:31:14

==============================================

Bart - I may be getting a bit confused here. According the DSL modem, these are the addresses it "sees":

DHCP starting address: 192.168.1.33
TCP/IP address 192.168.1.1

According to the router, this is what *it* sees:

LAN
IP Address
10.10.10.1
Subnet Mask
255.255.255.0
DHCP Server
Enabled

WAN
Connection
DHCP Client Connected
IP Address
192.168.1.33
Subnet Mask
255.255.255.0
Default Gateway
192.168.1.1
DNS
192.168.1.1

My brain is fried ... Perhaps yours can see the problem :D


Cheers
Dave
15 years 8 months ago #46065

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Replied by michael_murphy on topic Re: IP Addresses

Dave,

EDIT: I didn't see the post with the ipconfig/all and I think if I'm reading it correctly my setup is similar to yours.

I have a similar broadband setup at home. DSL modem connected to a router which is then connected to my PCs. As a result of the way i have configured the devices I have two private networks. One which my PCs are on and a second which has the 'WAN' side of the router and the DSL modem.

My DSL modem has two addresses the internet/outside-world/public address and an internal address 192.168.1.1.

The router is connected to the 'inside' of the DSL modem and that has an address given by DHCP from the DSL modem (usually 192.168.1.2).

The other side of the router serves addresses to the PC on the network in the domain 192.168.0.?.

If i were to try what you were doing I believe I would have to get the DSL modem to forward to a port on the router (192.168.1.2) and then get the router to forward this to the actual PC.

I don't know if this makes any sense but the gist is that you might need to forward from DSL modem to router and then from router to network. Hopefully this would address and NAT issues.

Michael.
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15 years 8 months ago #46067

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Replied by dmcdona on topic Re: IP Addresses

I don't know if this makes any sense


It makes sense alright but I'm not sure how to achieve what you are suggesting.

My DSL modem has the two address - private and public (LAN and WAN) alright. But I don't see anything (obvious) in the Modem's setup page allowing me to do port forwarding... Its available on the router configuration page alright... I guess I need to get these two black boxes talking correctly to each other...

Bart - its no problem changing internal IP addresses if necessary. I had, at one point, wanted to vonnect to our work network and I used IP numbers for my own network as recommended by our network guy. Hence the non-standard addresses. But they're easily changed (I think...)

Cheers
Dave
15 years 8 months ago #46069

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Replied by voyager on topic Re: IP Addresses

But I don't see anything (obvious) in the Modem's setup page allowing me to do port forwarding... Its available on the router configuration page alright... I guess I need to get these two black boxes talking correctly to each other...


Ah ... now I see the problem. To get through to your observatory PC from the outside world you need to traverse two routers. The Modem is DEFINTIELY doing NAT, the router MAY be doing NAT. If you can't do portforwarding on the first step, i.e. the modem then the traffic cannot get to router to be forwarded any further. Think of it as water trying to flow down hill through two locks. You've opened the second lock but not the first so naturally no watter is flowing.

I'm at a loss as to why you need a router AND a modem. This seems like a very strange setup. If the modem doesn't do portforwarding then you need to replace it. I'd suggest you replace it with a more default configuration and just get a single ADSL router which can do everything for you.

Hope that helps,

Bart.
My Home Page - www.bartbusschots.ie
15 years 8 months ago #46071

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Replied by albertw on topic Re: IP Addresses

I'm at a loss as to why you need a router AND a modem. This seems like a very strange setup. If the modem doesn't do portforwarding then you need to replace it. I'd suggest you replace it with a more default configuration and just get a single ADSL router which can do everything for you.


I need a router and a modem because my modem only has one ethernet port and no wireless :-)

Mind you I have everything on the one subnet which makes life easier.
Albert White MSc FRAS
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www.darksky.ie/
15 years 8 months ago #46072

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Replied by voyager on topic Re: IP Addresses

I'm at a loss as to why you need a router AND a modem. This seems like a very strange setup. If the modem doesn't do portforwarding then you need to replace it. I'd suggest you replace it with a more default configuration and just get a single ADSL router which can do everything for you.


I need a router and a modem because my modem only has one ethernet port and no wireless :-)

Mind you I have everything on the one subnet which makes life easier.


Then you need a switch! not a router! The two are very very very different things!
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15 years 8 months ago #46073

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Replied by albertw on topic Re: IP Addresses

Then you need a switch! not a router! The two are very very very different things!


No no, I need a router. Just trust me ok :-)
Maybe I lied a little when I said it was all on the same subnet :-)
Albert White MSc FRAS
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www.darksky.ie/
15 years 8 months ago #46076

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Replied by michael_murphy on topic Re: IP Addresses


My DSL modem has the two address - private and public (LAN and WAN) alright. But I don't see anything (obvious) in the Modem's setup page allowing me to do port forwarding... Its available on the router configuration page alright... I guess I need to get these two black boxes talking correctly to each other...


Dave, you should be able to get it working by using modem port forwarding to the WAN address on the Router to the same port (to keep things simple).
You then get the router to forward that port to the PC.

Michael.
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15 years 8 months ago #46077

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Replied by dmcdona on topic Re: IP Addresses

Mike - I tried that but to no avail....

What I did try, and it caused major problems, was to change the router address.

The DSL modem address is 192.168.1.1 so I made the router 192.168.1.50 This casued serious problems so I reverted the router back to its original address.

I messed about with the modem NAT table to try and get it to see either the router or the Observatory PC - to no avail. The Obs pc is now given a static address by the router - so I thought that might help...

I've tried every combination of DSL modem address, port forwarding addresses, NAT addresses I can think of. I think I'm ready to call it it a day and invest in a combined DSL modem/router.

Anything in particular I should be wary of or features I should demand?

Cheers
Dave
15 years 8 months ago #46097

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Replied by voyager on topic Re: IP Addresses

I think I'm ready to call it it a day and invest in a combined DSL modem/router.

Anything in particular I should be wary of or features I should demand?

Cheers
Dave


I think that's probably a good call. Best to keep things simple and your current setup certainly doesn't strike me as simple :(

I guess the main thing is just to be sure the DSL bit will work with your ISP. Also, in this day and age you should probably get integrated wireless and be dead sure the WiFi bit supports WPA2 because WEP is now totally totally broken and can be cracked in about 1 to 2 minutes.

Good luck!

Bart.
My Home Page - www.bartbusschots.ie
15 years 8 months ago #46100

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Replied by michael_murphy on topic Re: IP Addresses

Dave,

Sorry to here it didn't work. Getting a single device is right way to go. Bart's right about WEP you may as well not use it. If you do get a wireless device switch off the SSID broadcast (this will stop anybody with a wireless PC casually finding out about your network) and if you are not actually using the wireless network, switch it off. Remember, just because you're not paranoid, doesn't mean that they are not all out to get you :D

Michael.
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Replied by dmcdona on topic Re: IP Addresses

Success!

I popped down to PCWorld (spit) and managed to pick up a previously opened (but unused) DSL Router for 30 quid. Got a wirless notebook card thrown in for nowt as well - though I have wirelss disabled (not WPA2 Bart)

Whilst it has been tricky getting the settings right, all is now working OK.

Thanks to everyone for their input and help. Appreciate lads. That's what makes this site so cool. Especially now Bart has moved it to a brand new dual quad core Pentium iMac Pro...

Cheers
Dave
15 years 8 months ago #46108

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Replied by derrybawn on topic Re: IP Addresses

I've got a similar problem. I have an Irish Broadband Ripwave modem (wireless) connected to an SMC Barricade 7004 router via a LAN cable. It is supposed to do NAT.

Running 2 pcs side by side with one on an eircom dialup, I can do VNC from the broadband pc to the eircom pc, but not the other way around. I setup the SMC router to translate all the default services to the local ip of the machine.

From the eircom pc I'm using the format myIrishBroadbandIP:port with the port being the port address for the services setup in the router. I've tried all the port addresses for the services I setup (http, ftp etc). I'm not good on this stuff, but I can usually eventually figure it out. This has eluded me so far.

Anyone have any ideas on this? This is somthing I'd love to sort out.

Joe
15 years 7 months ago #47615

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Replied by voyager on topic Re: IP Addresses

I've got a similar problem. I have an Irish Broadband Ripwave modem (wireless) connected to an SMC Barricade 7004 router via a LAN cable. It is supposed to do NAT.

Running 2 pcs side by side with one on an eircom dialup, I can do VNC from the broadband pc to the eircom pc, but not the other way around. I setup the SMC router to translate all the default services to the local ip of the machine.

From the eircom pc I'm using the format myIrishBroadbandIP:port with the port being the port address for the services setup in the router. I've tried all the port addresses for the services I setup (http, ftp etc). I'm not good on this stuff, but I can usually eventually figure it out. This has eluded me so far.

Anyone have any ideas on this? This is somthing I'd love to sort out.

Joe


Opening up services to the world is very very dangerous. I'd suggest you investigate running a VPN, then you can get all ports from outside in a secure way.

I don't know how the ripwire router works so I can't really give much help.

Bart.
My Home Page - www.bartbusschots.ie
15 years 7 months ago #47618

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Replied by michael_murphy on topic Re: IP Addresses

Joe,

Subject to Bart's sound advice above, this should be possible.

I have a BT modem connected to a no name wireless router and have tested external VNC connections to my PC.

You need to get the broadband modem to port forward to the external address on the router (i.e. the router port connected to the broadband modem) and then get the router forward the same port to your PC. This is what I have done and it works for me.

As a first step it might be easier to connect your PC directly to the broadband modem and test that part out before bringing the router into the picture.

Michael.
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