PDA

View Full Version : Blocking IP form a website



noone
27-08-2005, 07:02 PM
How does this work

Doesnt your IP change everytime you reconnect or restart your modem etc ?

Jen
27-08-2005, 09:47 PM
If you are on dialup, then you will get a new IP each time you connect. Using broadband you can have sometimes a static IP or one that last for a period of time if you leave the modem/router always turned on. Turning off the modem will release that IP and you will be given a new one next time you connect.

Websites can block IP ranges, but that would affect everyone within that same range.

SurferJoe46
28-08-2005, 03:33 AM
Jen.....

this might prove to be an interesting subject for discussion here.

There is a lot of "olde wives' tales" about dynamic and static IP configurations. I don't pretend to know much about it myself, so maybe someone will like to log on and do some 'splaining for those of us who don't know about this subject.....

Any takers? :cool:

CorbinH
28-08-2005, 07:08 AM
my ip address has been the same for 2 years and ive reset the modem hundreds of times... its a cable connection

personthingy
28-08-2005, 02:59 PM
my ip address has been the same for 2 years and ive reset the modem hundreds of times... its a cable connectionThat's normal for cable in NZ too, but most DSL, dial-up etc is not fixed IP.

pctek
28-08-2005, 04:31 PM
And if you do a quick reset its likely to re-assign you the same one - to get a different one its best to leave it off for a short time.

SurferJoe46
28-08-2005, 04:50 PM
Then is there any reason to goto the C:\ and then renew after release the IP config?

I wonder about this, as this is about the first thing my ISP tells me to do when the wheels fall off.

personthingy
28-08-2005, 06:23 PM
Then is there any reason to goto the C:\ and then renew after release the IP config?

I wonder about this, as this is about the first thing my ISP tells me to do when the wheels fall off.???? Sounds dodgy to me!

pctek
28-08-2005, 09:51 PM
Then is there any reason to goto the C:\ and then renew after release the IP config?

I wonder about this, as this is about the first thing my ISP tells me to do when the wheels fall off.
Thats your internal IP - not the outside one your ISP assigns you.
They tell you that in case its gotten itself in a tangle and is not finding your router.

beama
28-08-2005, 11:18 PM
How does this work

Doesnt your IP change everytime you reconnect or restart your modem etc ?

It might your MAC address they use to block you (which cant be changed.............. Easily ;) )

SurferJoe46
29-08-2005, 04:22 AM
Thats your internal IP - not the outside one your ISP assigns you.
They tell you that in case its gotten itself in a tangle and is not finding your router.

Thanks...now that is something new I learned today...again, TY! ;)

personthingy
29-08-2005, 09:19 AM
It might your MAC address they use to block you (which cant be changed.............. Easily ;) )Time to stop nodding my head knowingly when i don't know.... What actually is a MAC address?

Rob99
29-08-2005, 01:31 PM
What actually is a MAC address?Basically it is a number your ethernet port has, every one in the world has a different one.
They are allocated by a governing body IEEE to the manafactures of these network ports.
They will eventually run out of numbers to asign and will have to come up with something else.

info here (http://standards.ieee.org/)

qyiet
29-08-2005, 02:00 PM
Can a webserver actually see your MAC address? I thought that data was used a couple of layers on the OSI model below the layer webservers use. Therefore becoming transparent to a webserver.

What usually happens with DHCP is that the server has a list of IP addresses it can give out. say 111.222.333.1->50.

Most DHCP servers just give these out in order, so the first client gets 111.222.333.1, the second 111.222.333.2, etc. However some DHCP clients (PCs/routers/whatever) ask for their old IP address back when they connect to the DHCP server again. Most servers will give it to them unless it has already been given out. Although some DHCP servers told the clients *must* rotate IP addresses.

So a router->dhcp server conversation would go something like this

Router:I had 111.222.333.27 last time, can I have it again?
Server:Hmm.. lets see, no noone else has it, it's all yours.
or
Server:Hmm.. lets see, dave already has it now.. have 111.222.333.41 instead
or
Server:Hmm.. lets see, no, the admins say I have to change your IP address every 2 hours, so here is 111.222.333.41 instead.

So in summary, *IF* you are on DHCP, not a static IP, leaving your router off for a while will most likely let someone else get your IP address to force a change.

-Qyiet

SurferJoe46
29-08-2005, 02:02 PM
Hmmmmmmmm.....did everybody say this was a dead topic and not interesting?...


Hmmmmmmmmmmm..again.

beama
29-08-2005, 03:26 PM
MAC addressing is not assigned by a server but rather hard coded into a chip. There are ways of whats known as spoofing an MAC Address but Jen may get upset if I said any more on the that particular topic

Jen
29-08-2005, 04:03 PM
MAC addressing is not assigned by a server but rather hard coded into a chip. There are ways of whats known as spoofing an MAC Address but Jen may get upset if I said any more on the that particular topicThere are also valid (legal) reasons why someone would want to hack the ARP table ...

I attended a very interesting presentation on this topic, and it was demonstrated just how easy it was to spoof a MAC address and what the consequences of this was. Unless your computer is a standalone sysem (not ever networked) and never accesses the internet, nothing is secure. :)

Graham L
29-08-2005, 05:02 PM
But a web site can't know the MAC address of a client, unless the client is on the same network. There is only room for one destination MAC address in a TCP packet. The destination is changed at each router to point to the next host in the route. The MAC address of the client is inserted in the packet by the last router to handle the packet, on the basis of its ARP table. That's how packets are routed.

Kame
30-08-2005, 04:58 PM
Graham is correct about the MAC (Media/Medium Access Control) Address, it's only seen within your own LAN.

Most networking devices have one.

A lot can be told from the first 3 bytes of the MAC address, which identifies the manufacturer of your network device.

As with blocking IP from a website, definitely a bad idea. Being able to find a unique identifier would be the best way of blocking in my opinion, but usually blocking the email address is viable too, since it requires the user to sign up for a new email address just to get back in, eventually they will tire (well hopefully).


Cheers,


KK

personthingy
30-08-2005, 09:23 PM
Graham is correct about the MAC (Media/Medium Access Control) Address, it's only seen within your own LAN.So just what is sent is a standard transaction between server and client apart from the obvous things such as requests for a page etc?

I've allways wondered exactly how a data manages to arrive at the correct client int a LAN. Is the local machines private IP address somehow added to the data sent out?

robsonde
30-08-2005, 09:44 PM
I've allways wondered exactly how a data manages to arrive at the correct client int a LAN. Is the local machines private IP address somehow added to the data sent out?


the sending computer decideds if the end point is on the LAN or not, this is done by checking the IP you are sending to with the subnet mask of the local system.

if the end point is on the LAN then the local computer sends a special packet to all systems on the lan that says "who has this IP and what is your MAC"
this is ARP/RARP. once the system has the MAC the packet is sent direct to that MAC address.

if the end point is not on the lan then the packet is sent to the default router.

once at the router the router uses much the same method to decide where to send the packet.

once at the local router of the end point the packet is sent by MAC address as with LAN.

the IP packet has a "return address" so every system along the way can see both where it is going and where it came from. an IP packet has other cruft atached to it, about 10% of each packet is cruft that makes IP work.


more info

http://www.networksorcery.com/enp/protocol/tcp.htm