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I don't have a great understanding of how networking works. From what I understand the WAN ip address which is visible to the outside world is different from thed LAN ip address. Inspite of that at any point in time isn't an ip address unique to one particular user? The reason I ask this is because we get a lot of spam from one particular ipaddress. If we report that user to the authorities, without any trouble they should be able to pin point the user, correct? My guess is they can take this WAN address that we provide them, to the ISP provider. And the ISP provider will be able to link this WAN to a LAN ip address, which can pin point the spammer.
Every host and a router on the Internet has an IP address, wich encodes its network number and host number. The combination is unique: in principle, no two machnies on the Internet have the same IP address. All IP Adresses are 32 bits long and are used in the Source address and Destination address fields of IP packets. You should note that an IP address does not actually refer to a host, but to a network interface, so if a host is on two networks, it must have two IP address, for example, if it is connected to local Ethernet, and to a WIFI(802.11) simultaneously. So, basically yes, you are correct, and the ISP provider should be able to locate it without difficulties.
EDIT: If the host is behind a NAT, then things can get a bit complicated, for example, if the user is spamming you from his office in a company, then that company gets the ip you are getting, but yet you are able to trace the company.
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I'm trying to enable port forwarding in my router (ZTE F660) but for some reason it is not working at all. First I started my server application in my ubuntu machine and I fixed its ip address to 192.168.1.2. Then, I set the rules as following:
It did not work. So, I've tried to disabled the firewall on my router settings:
It did not work as well, then I've disabled the firewall of my host machine by typing:
sudo ufw disable
And it did not work. Then, I tried to use many different ports and it did not work! :(
I've tried to use some port forwarding testers (like this one: https://hidemy.name/en/port-scanner/) and it always says that the state of the port is "filtered". I called the provider of my internet and they said that the port forwarding should be running but they did not offer technical help. Can anyone help me with this? Can't think about anything else to do.
Your ISP is using CGN (Carrier-Grade NAT) because your WAN address is in the Shared address space (100.64.0.0/10). That is not public address space, and it is defined by RFC 6598, IANA-Reserved IPv4 Prefix for Shared Address Space:
Abstract
This document requests the allocation of an IPv4 /10 address block to
be used as Shared Address Space to accommodate the needs of Carrier-
Grade NAT (CGN) devices. It is anticipated that Service Providers will
use this Shared Address Space to number the interfaces that connect
CGN devices to Customer Premises Equipment (CPE).
Shared Address Space is distinct from RFC 1918 private address space
because it is intended for use on Service Provider networks. However,
it may be used in a manner similar to RFC 1918 private address space
on routing equipment that is able to do address translation across
router interfaces when the addresses are identical on two different
interfaces. Details are provided in the text of this document.
This document details the allocation of an additional special-use IPv4
address block and updates RFC 5735.
The address block is detailed in Section 7:
7. IANA
Considerations
IANA has recorded the allocation of an IPv4 /10 for use as Shared
Address Space.
The Shared Address Space address range is 100.64.0.0/10.
That address space is also found in the IANA IPv4 Special-Purpose Address Registry.
What that means is that you have a home/residential ISP agreement. The ISPs are using CGN to save their precious public addresses for businesses willing to pay for them. The ISP NAT would also need to be configured to forward the port to your WAN addressing the Shared space, but the ISP cannot do that because others behind the CGN may also want that port forwarded to them.
The ISP does not really care that this breaks what you want to do because your residential ISP contract contains a clause forbidding you from running services from your network to the public Internet. You will need a public address and ISP permission to do what you want, and that probably means a business contract. The proliferation of CGN is a big driver for hosting companies, and that is an alternative way to do it.
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This questions is hypothetical, this situation would most likely never happen nor could any router handle it
Situation 1
Lets say for example you (somehow) managed to put 255 devices onto your network. Lets refer to the 255th device as D255 and, just for later reference, the router's IP address is 192.168.0.1. If I am correct D255's local IP address should be 192.168.1.255. So what if we buy a new device (D256) and connect it to my home internet along with the other 255 devices. What would D256's local IP address become? I thought about it and I assume that it would be 192.168.2.1. Am I correct?
Situation 2
After thinking about situation 1 I came up with another situation. What if you had 65025 (255 * 255 = 65025, if you see where I'm going with this.) devices connected to the your internet? The last device's (I will refer to as D65025) local IP adress should be 192.168.255.255 (That is assuming that situation1's solution is correct.). So what if I go out and buy a another device (D65026) what would it's local IP address be? It can't become 192.168.256.1 because the numbers can not exceed 255 and it can't become 192.169.1.1 because 192.168.x.x is the local IP reserve and 192.169.1.1 exceeds the local IP limit and (correct me if I'm wrong) would be a external IP address. So what would happen?
I appreciate your feedback!
A local network will typically be configured with a DHCP server to hand out IPv4 address leases along with name server addresses and a gateway address.
Residential and small commercial routers are usually configured to do Network Address Translation and have a DHCP server configured to hand out Private IPv4 addresses and the router's private IP as the gateway and nameserver. The size of the local subnet is determined by the router's configuration.
A typical configuration is 192.168.0.0/24 which provides 254 host addresses.
The DHCP server has configuration that specifies the address pool it can hand out leases for, how a DHCP server behaves if it is asked for a lease when all addresses in the pool are currently assigned depends on the configuration, but in most situations it will just not respond as there are "no free leases".
In this situation a host will likely select a link-local zero-configuration address from 169.254.0.0/16 and not have any Internet access or any other hosts on the network except those with Zero Conf addresses. It may retry DHCP at a later point.
The RFC1918 private address block 192.168.0.0/16 actually has capacity for 65534 uniquely addressed hosts. Ignoring the issues of having a layer 2 broadcast domain of this size, the same constraints apply: when there are no leases left to assign, none are assigned.
If these private addresses are to have Internet access they will be Network Address Translated to one or more public IP addresses (usually one) by the router. One public address is unlikely to be sufficient for a large number of private network hosts, constrained by the availability of local TCP / UDP port numbers.
I suggest you read up on IP networking to fill in basic knowledge.
If you are using DHCP, when you run out of addresses, it will kick one of the other devices off the network, probably the one which connected first. There are only so many devices which can connect to a network, but that number depends on the router configuration.
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When my PC is connected to Network, I will be getting couple of IP address.
1.) Modem Private IP address (will be like 192.168.1.3)
2.) ISP address (by searching "My ip address" in google it gives me my global IP address)
My roommate who is connected to same modem is able to ping my global IP address but not other person who is connected to different network, why??
Is there anyway that in ISP they block ICMP Packets?? So that no one be able to ping other machine ?? or do they use different routing instances for different sectors??
If we want a global IP address for my PC so that anyone can login/ping what should I enable??
Your router/modem gets a dynamic IP from ISP whenever you connect it to Internet. This address as name says is changing. If you want a constant public IP from ISP, you must request ISP for the same. This comes at a very high cost and not recommended unless you are serving a high revenue generating data on that machine.
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I've got a Draytek Vigor 2820 that's used to connect to the internet. WAN1 is used as an ADSL backup, and WAN2 is our main fibre connection. WAN2 has a total of 6 IP addresses, a single dynamic one and 5 static IPs and is configured up as a PPPoE connection with DynamicIP.
I use NAT Port Redirection to open up some specific ports to various servers (web development, FTP, RDC etc)
I use NAT Open Ports to open up some static IP ports to specific servers
I use NAT Address Mapping to force all traffic received on one static IP to our Exchange server
What I want to do is to force outgoing traffic to use one of the static IPs and have hit a brick wall. Ideally I'd like to force specific traffic but would settle for all!
Under LAN is the ability to configure Static Routes, but this is purely there to allow internal routing (for VLANs).
Anybody else who has this type of router and can give me any suggestions?
OK, managed to work this one out.
Under WAN > Internet Access, select WAN2
On the PPPoE page, change the "Fixed IP" to Yes and enter one of the static IP's into the Fixed IP Address box. Click OK and then reboot the router.
All traffic will now go from that IP address. If you go back to the same page and click WAN IP Alias, the top spot will have the IP address entered in it which will likely be repeated in the list, I just removed the 'double' from the NAT pool and everything seems to work OK.
Sadly there appears to be no way of having all traffic to one IP being sent via one static IP
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(1) What is my and others real IP address on same lan? Can we still have a unique IP despite the fact that we share the same router/LAN? and how does the IPs are assigned?
Thanks!
If you use a router to access the internet you probably have a DHCP Server running on the router as well.
This gives each computer a unique IP address wit a lease of x-days.
From the net only your public (mostly dynamic) ip address is shown to others.
Inside you private local net you have private ip addresses like 192.168.x.x/class C.
Easy way to find out your ip addess on your local computer:
open a cmd shell and type "ipconfig /all".
Then you see your IP address and also the gateway (which is your router).
Within a single LAN (which I'm defining here as a section of the net with no network address translation (NAT)), your IP address should be unique.
That's so that traffic can get to the correct machine.
However, it's never that simple. There's a good chance that the IP address the world sees you at is nothing like your local IP address. Your local address is probably 10.x.x.x or 192.x.x.x (from memory), one of a group of private IP ranges. For example, my Ubuntu box here is 10.1.1.2, an address that probably half a million other people on the planet have.
But my packets don't hit the internet with that source address since they go through a NAT router on my desk as well as a large number of other NAT'ting devices in my ISP.
It's this NAT process that allows all those private IP ranges to be usable.
As to how you get your IP addreses, you can set up static addresses (very useful for servers that you don't want changing) but the usual approach for non-server machines is to use a DHCP (dynamic host configuration protocol) server which manages the IP addresses and hands them out as required (on booting your client machine usually).
Typically, the DHCP server wil lock an IP address to a specific Ethernet MAC address for a period of time (in our corporate environment, it's three weeks). That means that, barring a four week holiday with your machine turned off, you should always have the same address.
Keep in mind that you may have more than one network card with separate IP addreses. You may even have a single network card with multiple IP addresses. In that case, you can be said to have more than one real IP address although I'd probably still say that it's the one servicing your default route (the source address your packets go out on by default).
It's a very ... interesting ... field to work in :-)