BribieG Posted April 23, 2007 Posted April 23, 2007 We have 2 computers, desktop and laptop, with a wireless DLINK thingy on the kitchen bench near the phone. Last night I was on the laptop and contributed something to Wikipedia but forgot to log in. Wiki notes your IP address when this happens. Today I got a message back regarding my post on Wiki, but the message 'alert' came up while I was on my desktop machine. Technical question - is my detectable IP address, therefore, the DLINK wireless router as opposed to each individual machine? Raises the more serious question, say I lived in an apartment and someone else in the building accessed my broadband and downloaded something illegal like child porn.....? I understand that all the authorities need is an IP address, a time/date, and evidence that you've done something illegal - with the proliferation of wireless networks, many of them not passworded such as mum and dad broadband, these seem like very muddy waters!
Mcrackn Posted April 23, 2007 Posted April 23, 2007 Yep the IP address that gets traced is that given to you by your ISP. That's why people use port forwarding to send certain connections to certain PCs.
aztec Posted April 23, 2007 Posted April 23, 2007 Yep the IP address that gets traced is that given to you by your ISP. That's why people use port forwarding to send certain connections to certain PCs. I thought the MAC address was used for tracing, as you've discovered, IP addresses are unreliable for this purpose.
FMB Posted April 23, 2007 Posted April 23, 2007 I thought the MAC address was used for tracing, as you've discovered, IP addresses are unreliable for this purpose. The MAC address does not get sent out across the internet. McCrackn is correct that its the IP address provided by your ISP. There are some ways around it, like using proxy servers. If you are running a wireless network, SECURE IT!!! I found out the hard way. I had my wireless network secured, but after a power blackout, the router defaulted to factory settings. Someone (I assume my evil neighbour) had accessed my PC. Now I'm careful to ensure the wireless network is really secure and that nothing of any value on any of my computers is shared.
wheresbaz Posted April 23, 2007 Posted April 23, 2007 The MAC address does not get sent out across the internet. McCrackn is correct that its the IP address provided by your ISP. There are some ways around it, like using proxy servers.If you are running a wireless network, SECURE IT!!! I found out the hard way. I had my wireless network secured, but after a power blackout, the router defaulted to factory settings. Someone (I assume my evil neighbour) had accessed my PC. Now I'm careful to ensure the wireless network is really secure and that nothing of any value on any of my computers is shared. I just set up a list of mac addresses that are allowed to log on to my wireless router I assume this is safe enough do you have encryption or something else turned on. Cheers Bill
FMB Posted April 23, 2007 Posted April 23, 2007 I just set up a list of mac addresses that are allowed to log on to my wireless router I assume this is safe enough do you have encryption or something else turned on.Cheers Bill Assigning specific MAC addresses is pretty secure. They can't be faked (at least as far as I'm aware). I also use a pre-shared key which is long and totally meaningless to anyone i.e. not my kids or pets names.
Austen Posted April 23, 2007 Posted April 23, 2007 Your ADSL modem connects to your ISP and receives an IP address. Then your router (or router function of your modem) assigns a "private" IP address (usually in the 192.168.x.x or 10.x.x.x range) to each of your networked computers..(unless you have assigned each 'puter its own address). So, (generally) as long as your modem is "up" your (external) IP address doesn't change................ If your modem stays on 24/7 its address may not change, but if you keep turning your laptop / mums laptop / desktop / kids computers on-off through the day their "private" address will change each re-boot. (Taking the next available from your router)......... That'll do for now .... Austen. PS, "Spoofing" MAC address....Degree of difficulty = 1/10
BribieG Posted April 23, 2007 Author Posted April 23, 2007 thanks guys, that's what I suspected! Will secure my network, haven't bothered up to now as all neighbours for half a K all round are on walking frames (Bribie Island retirement capital of Australiasia) but you never know. "Hey, sonny, guess what I've found out about you .... cackle cackle ....." :P
DrP Posted April 23, 2007 Posted April 23, 2007 Assigning specific MAC addresses is pretty secure. They can't be faked (at least as far as I'm aware). MAC spoofing is as easy as falling off a log. Anything that relies entirely on MAC addresses for security in a public environment is just asking for trouble.
Austen Posted April 26, 2007 Posted April 26, 2007 MAC spoofing is as easy as falling off a log.............. Actually, It's now even easier than that !! I noticed that one of the Top-Tier brand modems had just released a firmware update for one of their range of modems, one of the new features built into the modem is "MAC Address Spoofing". :ph34r: :ph34r: :ph34r: Austen.
aztec Posted April 26, 2007 Posted April 26, 2007 Assigning specific MAC addresses is pretty secure. They can't be faked (at least as far as I'm aware). I also use a pre-shared key which is long and totally meaningless to anyone i.e. not my kids or pets names. If MAC addresses are not sent out across the network how does the router know which MAC address the packets are coming from???
DrP Posted April 26, 2007 Posted April 26, 2007 MAC addresses do not normally propagate across routers. They are only useful for LAN comms or for comms across bridges / switches.
aztec Posted April 26, 2007 Posted April 26, 2007 MAC addresses do not normally propagate across routers. They are only useful for LAN comms or for comms across bridges / switches. I thought the MAC address was embedded in the IP packet headers?
aztec Posted April 26, 2007 Posted April 26, 2007 I thought the MAC address was embedded in the IP packet headers? From techweb.com "Ethernet wraps the IP datagrams into its own frame format, which includes a header with source and destination MAC addresses (station addresses) and a trailer that contains checksum data." So my assertion that MAC addresses are used for tracking is correct, I believe. I could be wrong though, I am not into forensics.
aztec Posted April 26, 2007 Posted April 26, 2007 but if you keep turning your laptop / mums laptop / desktop / kids computers on-off through the day their "private" address will change each re-boot. (Taking the next available from your router)......... Not quite right, every time a request is made to a dhcp server you get a lease time, the value of which is usually configurable. So if you turn off your machine but turn it on before the lease time expires you will get the same address.
Austen Posted April 26, 2007 Posted April 26, 2007 Not quite right, every time a request is made to a dhcp server you get a lease time, the value of which is usually configurable. So if you turn off your machine but turn it on before the lease time expires you will get the same address. I was just trying to KISS for the OP, trying to show that on a home network the 'puters get their IP address from your router, NOT from the ISP ...... But I must admit, I didn't know that the router keeps (your 'puters MAC address) in memory and returns the same IP on computer re-boot if the lease is still valid. I thought that when your 'puter asked for an IP address, it always got the "next-available".............. So to take things to the extreme, if a router is configured with a range of (say) 10 IP address to hand out, with a lease time of 1 week, and this it does, then all 10 of the connected computers are turned off, and an eleventh one is turned on, there will be no spare IP Addresses available for the eleventh computer until the week has expired ? Austen.
aztec Posted April 26, 2007 Posted April 26, 2007 I was just trying to KISS for the OP, trying to show that on a home network the 'puters get their IP address from your router, NOT from the ISP ......But I must admit, I didn't know that the router keeps (your 'puters MAC address) in memory and returns the same IP on computer re-boot if the lease is still valid. I thought that when your 'puter asked for an IP address, it always got the "next-available".............. So to take things to the extreme, if a router is configured with a range of (say) 10 IP address to hand out, with a lease time of 1 week, and this it does, then all 10 of the connected computers are turned off, and an eleventh one is turned on, there will be no spare IP Addresses available for the eleventh computer until the week has expired ? Austen. Correct. You need to balance the lease time against number of devices.
Mcrackn Posted April 27, 2007 Posted April 27, 2007 I have my router set to assign a specific IP to each computer based on the MAC address. This way I have the same IP on each machine all the time (for setting up port forwarding for webscheduler, ftp, etc.) Saves me having to go to each PC and set a static address.
DrP Posted April 27, 2007 Posted April 27, 2007 From techweb.com"Ethernet wraps the IP datagrams into its own frame format, which includes a header with source and destination MAC addresses (station addresses) and a trailer that contains checksum data." So my assertion that MAC addresses are used for tracking is correct, I believe. I could be wrong though, I am not into forensics. Only in so much as for LAN sgement traffic. Packets that flow through a router (and some bridges too) get the source MAC replaced with the MAC address associated with the far side interface on the router normally*. When your PC sends a packet to an off LAN IP address, the destination MAC address in the packet is that of the router that your PC thinks it should ship the packet off to for delivery to the next hop/final destination. *simple home ADSL routers are a different case. Quite often these devices have their WAN interface configured with PPP. The ethernet MAC addresses have no place in the PPP world and simply don't get involved. If the home router is using PPPoE, then the router's own virtual MAC will be inserted into the outgoing packet. Unless your ISP uses their own equipment rather than Telstra Wholesale, its far far better to configure a home router to use PPPoA rather than PPPoE. Telstra in their (apparently) infinite wisdom have configured their equipment to consider multiple connect attempts (failed or otherwise) using PPPoE as an attack and to silently drop all PPPoE frames with your router's MAC address.
tonygib Posted April 27, 2007 Posted April 27, 2007 I have my router set to assign a specific IP to each computer based on the MAC address. This way I have the same IP on each machine all the time (for setting up port forwarding for webscheduler, ftp, etc.) Saves me having to go to each PC and set a static address. I actually do it the other way around. I hard set my IP's on each comp and then assign port forwarding to those specific IP's (ie only the computers that need them), hence everything else is blocked at my modem/router. I also turn off any DHCP,etc on the modem/router, so to stop any snooping, etc. Any remote management is off too and of course it goes without saying (well it should, but you would be surprised) that you change your modem password from the default. I'm also all wired, no wireless stuff, so while I'm not saying I'm rock solid secure, it should be pretty hard to 'break-in', hard enough that any script kiddies would just move on to an easier target.
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