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NETWizz
Byte by bit
Bandwidth Hog
Joined: 20 May 2003
Posts: 2369
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 Posted: 01 Mar 2005 02:20:08 am Post subject: |
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Arcane Wizard wrote: alexrudd wrote: Not that they could detect you easily
It's pretty easy actually, you just show up on their network, so they could just check what your MAC adress is and use a MAC-scanner (kind of like an advanced metal detector) to find where you're hiding.
At least that's what they do at my college when you scan everybody on the entire network for open ports. 
Quote: As for not paying for internet, I've heard there are people that go around doing that. They have WiFi "sniffers" or whatever, and whenever they find an open network, they use a code to tell their friends. (Chalk mark on sidewalk, etc.) I've never done it, but I think it would be fun to try. Laptop or PDA with Wifi + autoconnect + play sound on connect, or a program that logs all WLANs found/connected to comes in handy. Especially usefull when you go to work/school with the train and want an almost continuous connection, just store the log with all it's settings and recall it when you start the trip.
It doesn't work quite that way.
By joining their network, DHCP on their router will give you an IP address which consists of their network id and your assigned node number as defined by the subnet mask.
On a standard Class-C home network:
192.168.0.7 / 255.255.255.0
The address of your node is 192.168.0.7 in this case and the first 24 bits (CDIR Notation) are masked out. Note that is the first 3 Octets (Bytes).
In this standard situation the 192.168.0 is the network address and 7 is your node number on the network. This network is defined as being 192.168.0.0 that is the network id. The broadcast id will be 192.168.0.255
Obviously, this means you will be able to see, ping, play multiplayer games with... anyone in the 192.168.0.0 network so you can talk to 192.168.0.1 to 192.168.0.254
Anything above or below you cannot talk too. If you do not belive me, try setting a computer up for 192.168.1.* I guarantee you that computer will not talk to any computer on 192.168.0.*
It quite simply belongs to a different network and as such you cannot talk through the MAC or the PHYSICAL layer of the OSI Model. You woulud need a router to connect the different networks, and even then it would be bending the rules on a for a Class C network.
Essentially, you have to borrow bits from the node address space when you subnet.
So, instead of 255.255.255.0 you could create 255.255.255.192
That would be
11111111.11111111.11111111.11000000
nnnnnnnn.nnnnnnnn.nnnnnnnn.sshhhhhh
ch for host, host = node e.g. printer or computer
n for network
s for subnet
That would leave you with only 6-bits to make host
You would have a small mess subnetting like that.
e.g. Networks
192.168.0.64 would be the first network id
192.168.0.65 through 192.168.0.126 would be for computers, nodes, hosts...
192.168.0.127 would be the brodcast address for that network
192.168.0.128 would be the next network.
Belive it or not, computers 192.168.0.65 and 192.168.0.129 would not be able to taok to each other because TCP/IP would classify them as belonging to a different subnet.
You could then use a router or two to to make them talk. You would need one router with ethernet 0 and ehternet 1 or two routers each with ethernet 0 and serial 0
If you had more than one router, you would have to connect the serial connections, configure the networks, setup a static route or install a routing protocol such as RIP or IGRP, and finally set a clockrate on one of the serial ports to clock the communications between routers.
What I am getting at is you cannot borrow in reverse. In other words, you are required to use at least a 24 bit mask with a class c address. You cannot use a smaller mask.
If you really want to setup networks, use a class b or a setup and good loard, add an entire extra byte to the subnet mask to make life easy.
e.g. 172.16.0.0 network uses 255.255.0.0 as default
if you use 255.255.255.0 you can make it into almost 255 networks
172.16.1
172.16.2
...
Would all be networks and easy to connnect together.
With the defualt mask of 255.255.0.0 for a Class B address such as the above, you would just use 172.16.*.*
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As for your neighbors.
When DHCP gives you an IP address, it also gets a copy of your MAC address.
XX-XX-XX-XX-XX-XX is the MAC address format.
Essentially, DHCP is saying XX-XX-XX-XX-XX-XX has leased 192.168.0.7 or whatever for a lease time.
When that lease expires it is up fro grabs though DHCP actually renews it before it expires. About 50% if I remember correctly. Standard lease is about 7-8 days.
Your MAC address is burned on your card and never changes. It is a unique identifyer. No two computers should have the same MAC address.
As for MAC addresses, they get stripped off and replaced when you cross subnets via routers or network routers and replaced with other ones.
In other words, a MAC address is only good for transferring data within a given SUBNET. It is not routeable. Hence the failure of Microsofts NetBuei protocol.
*/IP and */IPX as well as others can cross networks becuase they contain a Network ID number in addition to the Host ID number. Hence, they are routeable.
Your mac address cannot be determined from a different subnet. Well unless there is some program to ask your computer its MAC address via its IP address.
You can use ARP and Reverse ARP to convert between MAC addresses and IP addresses.
You can typically do c:\>arp -a 192.168.0.7 or something similar to look up a MAC address of a computer. It will look up an ARP table.
BTW, hubs move traffic at the physical layer thus are stupid.
Switches, keep track of traffic at the Data Link Layer via MAC addresses. In other words, each time data is requesed or sent or a new computer appears it registers its IP address with a MAC address. The Switch then knows exactly where each computer is on the network by the use of an ARP table with MAC entries.
A router uses the Network Layer to connect networks together via routeable protocols such as TCP/IP to exchange data. They typically use routing protocols such as RIP or IGRP to keep track of the routers on the Wide-Area-Network.
Your College
It is more likely they run a Ping Sweep to sweep the entire DHCP range of addresses your college assigns. This consists of Ping on each address and port scan to find open ports. Unless they have a MAC address list that has your MAC address and Name by it, they will have a hard time tracking you. All they will see is such and such IP accessed something at a certain time. To them, their network is likely LAN that looks rather FLAT. In other words, they might know that a certain IP is doing bad things but not know the location of the computer with that IP address. It would take an awfully expensive swith to have a feature to tell you what port a particular IP address is using. Then they would just need to follow it to the patch pannel and they would know where you are plugged in. I serriously doubt they are that advanced.
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Sniffers
You are thinking of MiniStumber for the Pocket-PC or Network Stumbler for a laptop.
These programs spot networks and gather statistics. It is usually quite easy to find and u se an open network.
Before you do so, you should make sure to disable your Microsoft Networking Client and/or firewall yourself.
Remember, you do not want the person who's network you connect to also have access to any of your shared files.
Last edited by Guest on 01 Mar 2005 02:37:48 am; edited 1 time in total |
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Arcane Wizard
`semi-hippie`
Super Elite (Last Title)
Joined: 02 Jun 2003
Posts: 8993
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| Posted: 01 Mar 2005 02:47:33 am Post subject: |
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Jbirk wrote: It doesn't work quite that way.
If you can talk to their network, they can talk to you.
If your address is 192.168.1.* on a 192.168.0.* network you won't be on their network in the first place.
At least, by my standard, you're not on somebody's network when you can't talk to that network at all.
Quote: Your MAC address is burned on your card and never changes. It is a unique identifyer. No two computers should have the same MAC address. You can easily change your MAC address..
Quote: Your mac address cannot be determined from a different subnet. Well unless there is some program to ask your computer its MAC address via its IP address. But you know it's easy enough when you are in the same subnet range.
Quote: Your College
It is more likely they run a Ping Sweep to sweep the entire DHCP range of addresses your college assigns. This consists of Ping on each address and port scan to find open ports. Unless they have a MAC address list that has your MAC address and Name by it, they will have a hard time tracking you. All they will see is such and such IP accessed something at a certain time. To them, their network is likely LAN that looks rather FLAT. In other words, they might know that a certain IP is doing bad things but not know the location of the computer with that IP address. It would take an awfully expensive swith to have a feature to tell you what port a particular IP address is using. Then they would just need to follow it to the patch pannel and they would know where you are plugged in. I serriously doubt they are that advanced. However they do it, if I would use my laptop, which is connected to a wifi access point, to start scanning 145.92.*.* right now, an annoying fellow with a scanner showing the nearest wifi signal's mac address would show up in a matter of minutes.
Quote: Sniffers
You are thinking of MiniStumber for the Pocket-PC or Network Stumbler for a laptop. Yeah that's the stuff, couldn't remember the name. |
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NETWizz
Byte by bit
Bandwidth Hog
Joined: 20 May 2003
Posts: 2369
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| Posted: 01 Mar 2005 02:57:09 am Post subject: |
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Quote: If your address is 192.168.1.* on a 192.168.0.* network you won't be on their network in the first place.
At least, by my standard, you're not on somebody's network when you can't talk to that network at all.
No shit, though you can use their hardware. e.g. you can setup a whole range of like addresses that are different than theirs via static IP. All you need is to plugin or know the SSID of a wireless AP.
If they are using 192.168.0.* you can use 192.168.X.* where X is not 0
Set a static IP on all your computers and use their hardware.
You cannot easily change the MAC address though Widnows.
the MAC address is burned in ROM or EEPROM on your NIC.
At the very least it is in NVRAM. It is Non-Volitile Memory.
To change the MAC address, you would need a special utility to reflash the MAC address. Yes, I am sure some nics let you chagne it with a special program they include.
However, each NIC has a different process and usually this means Flashing. It is not "Easy"
Besides the first three XX-XX-XX usually are unchangeable. The represent the manufacturer. Elg Brodcomm, Intel, ...
When you authenticate to an Access Point, you can see its MAC address. True.
Last edited by Guest on 01 Mar 2005 02:57:39 am; edited 1 time in total |
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