Dave Posted January 24, 2005 Report Share Posted January 24, 2005 Can someone explain IP address and how they can be traceable? Everytime I log on to the internet I know that i am assigned an IP address.. is it a different one every time or the same number? and if I have three different computers with which I browse the internet, do they all come up with different addresses or is the Ip address related to my login information Cheers Dave Link to comment Share on other sites More sharing options...
Mollox Posted January 24, 2005 Report Share Posted January 24, 2005 Hehe might as well dive in before the techies get here An IP address is made up of four 'octets'. These are four ranges from 0-255 and so a typical IP address might be 153.78.231.98 where any of the numbers between the dots can be 0-255. You will either have a static (fixed) IP or a dynamic one assigned by your ISP each time you logon. If you have a fixed one, its easy for an someone with the right authority to trace it back to you as you're the only person at your ISP that uses that IP. If you're on a dynamic IP the first 2 octets will most likely be the same, the 3rd probably won't change too much so your IPs from 3 logons might look like: 153.78.231.98 153.78.231.112 153.78.231.99 Now, with 3 machines, it depends on how they're conncted to the net. If you have 3 separate dynamic IP contracts with an ISP then they might have 3 different IPs at the same time, much like the example above. If all 3 connect via a router, then you will have one IP to the outside world and your 3 PCs will have "internal IPs" from a 'subnet' and these tend to follow typical IP subnets such as 198.162.0.x so your first PC would have the IP 198.162.0.1, the 2nd 198.162.0.2 and the 3rd 198.162.0.3 or any random combination of 0-255 for the last octet. Basically, these get assigned by something called DHCP which is a feature of most new routers. In this case, all 3 pcs are seen by the outside world as one IP - again, it could be 153.78.231.98. Bit of a hackneyed, non-IT explanation but its from one non-techy to another so it might make sense Link to comment Share on other sites More sharing options...
Rugbyfiend Posted January 24, 2005 Report Share Posted January 24, 2005 i have a bit of a follow up question to this. Why are internal ip addresses (as in the ones between computer and router) normally of the sort 192.168.X.Y where x always seems to be either 0 or 2. Can this be changed to anything else eg 246.53.X.Y or should they always be of that type? Do i remember something about them being non-routable, or is that a figment of my imagination? Link to comment Share on other sites More sharing options...
Mollox Posted January 24, 2005 Report Share Posted January 24, 2005 I THINK you can set manual IPs on a subnet - providing both ends match. I'm getting into murky water now so will leave it to the experts Link to comment Share on other sites More sharing options...
Frodo Posted January 24, 2005 Report Share Posted January 24, 2005 Mr. Rugbyfiend the 192.168.x.x and also 10.x.x.x are reserved private addresses that can't be used on the internet. Therefore every company in the land can have these IP addresses internally and access the internet through a single unique IP address. When you access the internet directly then you must have single unique IP address. Most routers / firewalls that face the internet will have a unique IP address which either is either dynamic or static. But behind the firewall / routers are local computers that have a reserved IP address range. The router than maps connections to internal IP addressed in a method called Network Address Translation (NAT) or could also use ports instead of addresses in a process called Port Address Translation (PAT) however this is less common. Link to comment Share on other sites More sharing options...
Frodo Posted January 24, 2005 Report Share Posted January 24, 2005 Yes you can you can use 192.168.0.1 or 192.168.0.254 or 192.168.255.254 all are valid internal addresses. The IP address also has an associated sub-net mask and is classed into an address range. This starts getting very complicated and I am sure someone can explain this better than me. For example 192.168.0.x usually has a sub-net mask of 255.255.255.0 or class C. Whereas the other reserved address range 10.x.x.x has a subnet mask of 255.0.0.0 and is class A. Link to comment Share on other sites More sharing options...
Rustynuts Posted January 24, 2005 Report Share Posted January 24, 2005 [ QUOTE ] Yes you can you can use 192.168.0.1 or 192.168.0.254 or 192.168.255.254 all are valid internal addresses. The IP address also has an associated sub-net mask and is classed into an address range. This starts getting very complicated and I am sure someone can explain this better than me. For example 192.168.0.x usually has a sub-net mask of 255.255.255.0 or class C. Whereas the other reserved address range 10.x.x.x has a subnet mask of 255.0.0.0 and is class A. [/ QUOTE ] Link to comment Share on other sites More sharing options...
Rugbyfiend Posted January 24, 2005 Report Share Posted January 24, 2005 Mr Frodo, i think i'm getting this, so i understand that 192.168.x.x and 10.x.x.x can't be used on the web. But could you use any combination of numbers as your internal addresses and its just convention that 192.168.x.x is used, so when looking at such an address, a network admin can say "aha, an internal address". Or is that the addresses have to be 192.168.x.x to work on an internal network, otherwise all the computers "think" that they are connected to the web which no doubt would cause all sorts of exciting happenings. It's just my thinking that if you have a modem with a unique static ip, it is only this ip address that has to be unique. The ones on the other side can be anything so as long as the range is properly specified in modem and router is it possible? I'm starting to confuse myself now, so will stop, post, read again and edit as needed but i hope i (sort of) am getting my question across, and it's only 'cos i'm nosy and interested, nothing earth shattering is relying on this (well not yet anyway...) Link to comment Share on other sites More sharing options...
Mac Posted January 24, 2005 Report Share Posted January 24, 2005 You COULD use any IP address you liked on your internal network....it's not good practice though and also has some big downsides. Say you use 207.46.250.222 as an internal address..that's all fine apart from the fact that this happens to be the SAME IP address as used by www.microsoft.com therefore you wouldn't <font color="#666666"> </font> without some technical buggary <font color="black"> </font> be able to connect to www.microsoft.com. By using the internal address ranges you avoid this type of issue. Also, who managed CLASS C Technically most systems do not use classes now for routing (I.e. classless routing) however people still refer to class A/B/C networks to refer to the number of bits in the subnet mask - I.e. 8/16/24 etc. Bang? Link to comment Share on other sites More sharing options...
Rugbyfiend Posted January 24, 2005 Report Share Posted January 24, 2005 [ QUOTE ] You COULD use any IP address you liked on your internal network....it's not good practice though and also has some big downsides. Say you use 207.46.250.222 as an internal address..that's all fine apart from the fact that this happens to be the SAME IP address as used by www.microsoft.com therefore you wouldn't <font color="#666666"> </font> without some technical buggary <font color="black"> </font> be able to connect to www.microsoft.com. By using the internal address ranges you avoid this type of issue. Also, who managed CLASS C Technically most systems do not use classes now for routing (I.e. classless routing) however people still refer to class A/B/C networks to refer to the number of bits in the subnet mask - I.e. 8/16/24 etc. Bang? [/ QUOTE ] fantastic get it now, its all about conflicting with addresses already on the web, hence the reserved private ones. Cheers, i shall sleep easier tonight! Link to comment Share on other sites More sharing options...
Frodo Posted January 24, 2005 Report Share Posted January 24, 2005 Glad you understand it but just to put a spanner in the works this is all now legacy and we should be talking about IPv6. Which gives addresses in Hex. Link to comment Share on other sites More sharing options...
Mac Posted January 24, 2005 Report Share Posted January 24, 2005 [ QUOTE ] Glad you understand it but just to put a spanner in the works this is all now legacy and we should be talking about IPv6. Which gives addresses in Hex. [/ QUOTE ] Be nice Confusing the little fella - that's just mean Link to comment Share on other sites More sharing options...
Frodo Posted January 24, 2005 Report Share Posted January 24, 2005 but did you notice I didn't expand on IPv6? That is because I know absolutely bugger all about it. I have become very niche looking after mail servers in a coperate environment. I forgotten loads on servers, workstations and networks. Link to comment Share on other sites More sharing options...
Belchy Posted January 24, 2005 Report Share Posted January 24, 2005 A great place to pick up basic subnetting/ip addressing is here ... Its worth the effort to understand this topic ... you will get loads of "ohhh thats why its like that" scenarios during your time on the site. I used this site for study some time ago and found it very informative as a starting point ... which it seems is all you need Link to comment Share on other sites More sharing options...
Colin M Posted January 24, 2005 Report Share Posted January 24, 2005 I used this site for study some time ago Presumably when you were still using Internet Explorer? It doesn't want to play with Firefox. Link to comment Share on other sites More sharing options...
Belchy Posted January 24, 2005 Report Share Posted January 24, 2005 [ QUOTE ] Presumably when you were still using Internet Explorer? It doesn't want to play with Firefox. [/ QUOTE ] I still use IE and will continue until I see a reason to quit Link to comment Share on other sites More sharing options...
tainted_love Posted January 25, 2005 Report Share Posted January 25, 2005 on the topic of IP address, can you have your main IP address changed?? am asking as my system is getting hit constantly by dodgy sites , using firewall but knowing that my IP could change is good idea, would ntl change it??? Link to comment Share on other sites More sharing options...
Frodo Posted January 25, 2005 Report Share Posted January 25, 2005 If you have a static IP address then they might, but if it is dynamic it is a lottery. If you router picks up a dynamic address it is leased from the DHCP server, when you reboot the router and it is within it's lease then it is likely to get back the same IP address. Anyway chances are you are probably being port scanned by script kiddies but so long as you have a firewall then no need to worry it would be the same whatever your IP address. Link to comment Share on other sites More sharing options...
IanHo Posted January 25, 2005 Report Share Posted January 25, 2005 The private addresses mentioned on this thread are defined by Request for Comments (RFC) 1918. RFC's are published by the Internet Engineering Task Force (IETF). RFC's define all aspects of TCP/IP and associated protocols & standards. You, me or anyone can submit an RFC for consideration as an Internet Standard. To clarify reserved Internet addresses for Private Internets are as follows: 10.0.0.0-10.255.255.255 or 10.0.0.0/16 172.16.0.0-172.31.255.255 or 172.16.0.0/12 192.168.0.0-192.168.255.255 or 192.168.0.0/16 You would always be wise to use a subnet within the above address spaces in your private (internal) network, to avoid any possible conflict with assigned Internet Addresses. Although as stated previously you could use any IP address, it is good practice not to. Using "non reserved" addresses will not cause a problem on the Internet, but will prevent you connecting to systems on the Internet that use the same IP address space. As a best practice always use RFC1918 addresses on your Internal network(s). Link to comment Share on other sites More sharing options...
Munki Posted January 26, 2005 Report Share Posted January 26, 2005 To clarify reserved Internet addresses for Private Internets are as follows: 10.0.0.0-10.255.255.255 or 10.0.0.0/16 172.16.0.0-172.31.255.255 or 172.16.0.0/12 192.168.0.0-192.168.255.255 or 192.168.0.0/16 Is exactly what I was gonna say. Link to comment Share on other sites More sharing options...
Foggy Posted January 30, 2005 Report Share Posted January 30, 2005 [ QUOTE ] Glad you understand it but just to put a spanner in the works this is all now legacy and we should be talking about IPv6. Which gives addresses in Hex. [/ QUOTE ] <pedant mode> Both IPv4 and IPv6 are binary addresses, an IPv4 address being 32bits and an IPv6 being 128 bits they are just represented using decimal/hexadecimal to make them more readable for humans. </pedant mode> Link to comment Share on other sites More sharing options...
M3Will Posted February 7, 2005 Report Share Posted February 7, 2005 10.0.0.0-10.255.255.255 or 10.0.0.0/16 <--- should be a /8 not a /16 ! Link to comment Share on other sites More sharing options...
IanHo Posted February 10, 2005 Report Share Posted February 10, 2005 Hmmmm how did that happen, gained an extra 8 bits from somewhere must have come free with something! Well spotted . Link to comment Share on other sites More sharing options...
newone Posted March 15, 2013 Report Share Posted March 15, 2013 Can someone explain IP address and how they can be traceable?Everytime I log on to the internet I know that i am assigned an IP address.. is it a different one every time or the same number? and if I have three different computers with which I browse the internet, do they all come up with different addresses or is the Ip address related to my login information Cheers Dave IP address is of two types,Internal IP and an External IP.Internal IP is one that each device like computer,printer has.The external IP is the one through which one gets connected to the internet.The External IP is got from the ISP and is classified into static and dynamic where static IP does not tend to change and the dynamic IP varies each time the modem is switched ON and OFF.If you have a dynamic IP then there are chances every-time you log on to the internet you are assigned a new IP.The duration to the change in IP depends on your ISP.If all your computers share the same modem with a static IP then there will be no change in IP address;if you use a dynamic one then each computer will have a different public IP address.You can check this through I'm a Spamming [email protected] which displays your public IP when you visit the site. If you logon to any forum or website the admin has priveleges to know from which IP you logon,through which your IP can be traced. Link to comment Share on other sites More sharing options...
Scotty Posted March 15, 2013 Report Share Posted March 15, 2013 8 years too late. I think this gets the 2013 Thread Resurrection of the Year (so far) Award. Link to comment Share on other sites More sharing options...
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