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blocked site

#1
is there a way that someone can block a site of a user over the internet.

like no software put on there computer but they cant access one site through there modem. the IP is changed many times but you still cant connect to it. cant ping it. nothing.

nothing in host file blocking it. nothing in IE and Firefox.
tested on 2 different computers on the network
both are dual boot. xp and vista. neither can connect.

no spy ware recorded and no viruses.

any ideas?

i have also left the modem unplugged power wise and disconnected to change my ip many times.

and if i reboot. open connection, then firefox. and try to access it, and no go. if netstat its only 2 connections trying to get to it as well.

and the site is up if i use my neighbors wierless LOL
any ideas? its bugging me
 
#3
Or they have your modems MAC address blocked. Gaming sites used to block MAC addresses if you were banned for misconduct.

We know because we tried to sneak back in and ruled out everything but the MAC.
 

fitz

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Political User
#4
Or they have your modems MAC address blocked. Gaming sites used to block MAC addresses if you were banned for misconduct.

We know because we tried to sneak back in and ruled out everything but the MAC.
it wouldn't be possible to block the source mac address as it would change after each router hop.
 

fitz

Woah.. I'm still here?
Staff member
Political User
#7
In all my network traces that I've done over my lifetime, unless I had access to the switches and routers in between, I have never been able to sniff the original MAC address.

and router does change the packet. It rewrites the header info that contains source/destination addresses. If they didn't change the source and destination MAC address, it wouldn't be able to route the packet correctly.

edit:
http://www.petri.co.il/csc_routers_switches_and_firewalls.htm
Routers replace the Ethernet MAC address of the source device with their own MAC address when they send a packet out an interface. When the response to that packet comes back, the new source of the packet is sending the response to the destination of the router. The router receives this, replaces the source address, changes the destination address to the original address, and sends the packet back to the original sender. This is a complex topic that we could spend a whole article covering so this is only meant to provide the most basic understanding of how this works.
 
Last edited:
#8
It basically comes down to the following:

Internet routers do not care where a packet came from, only where it's going. Therefore they leave the origniator mac address and ip address alone while forwarding it on to the next best hop for its destination.

Destination host then replies and addresses the packet to the originator mac and ip address and fires the packet off to the first routing device in the journey.

This I have learned in the three years I've been working at an ISP.
 

fitz

Woah.. I'm still here?
Staff member
Political User
#9
Really? All my network traces I've ever done tell me otherwise..

Cisco docs tell me otherwise.. the Source/Dest IP will stay the same, the MAC address HAS to change for the packet to be routed correctly..

http://www.ciscopress.com/articles/article.asp?p=102093&rl=1
Because Router-A is connected to Router-B via Ethernet, Router-A must send the IP packet inside an Ethernet frame addressed to Router-B. To determine the MAC address associated with the next hop router, the local ARP cache on the router is checked to see if an entry exists for the IP address of the next hop. If no entry exists, then the router must generate an ARP request, asking for the MAC address associated with the next hop IP address (this is a control plane operation). Once the correct destination MAC address is known, the routed frame destination MAC address can be rewritten. The source MAC address is also rewritten to the MAC address of the Ethernet 1 interface on Router-A so that Router-B knows it received the frame from Router-A. It is this process of rewriting the frame MAC addresses that represents the key concept of data plane operations—A router does not modify the source or destination IP addresses of IP packets that are being delivered, but rather it must rewrite the destination and source MAC address so that the IP packet can be delivered over the LAN to the next hop.
 
#11
i have changed to a new modem and it has done the trick.
i also called the IPS and that was no help. the dude didnt know squat.
and the site was facebook LOL its just weird that it was blocked from me seeing it with that modem weather it be mac address or something. not sure why it would be tho.
 

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