Conflicting IP addresses

I recently got a lifetime ban from a discussion forum!!**?? Although I can be a bit hasty with comments sometime I never offend so this rather confused me. On making contact it appeared that the culprit was not me but somebody using the same IP address. I know IPs are variable but I thought that they only changed following a full log off.

What worries me is that if an IP is used to trace a serious crime I could have spent the last week in Strangeways, or even longer. A bit worrying.

Meldrew

There is no reason for an IP address to stay fixed for the entire session, though there may be a tendency to do so - but if a piece of equipment needs to be taken out/rebooted in ISP then connections may be dropped and re-connected.

if the police were seeking the location behind the IP address, then they would go to PlusNet and get the account at the time - PlusNet's systems record when the IP address was re-assigned, so unlikely you'd get a visit.

Discussion forums don't have access to that information and are unlikely be able to do much with it - where as banning an IP address is easy, but often futile as it is often easy to work around.

Assuming the person isn't on your connection, other than the odd pain dealing with such bans there isn't a huge amount to worry about - personally I got a fixed IP address from PlusNet which would generally stop such things, but I got it so I can remote access home

IP address spoofing wiki.

Apparently Digital Spy ban people on the basis of their IP address and then link it to the user name. Clearly it is possible to get them mixed up.

In reply to a post by meldrew:

Apparently Digital Spy ban people on the basis of their IP address and then link it to the user name. Clearly it is possible to get them mixed up.

True, but other than IP addresses, websites have little else to work with. Cookies can be set, but are just as easily deleted, so IP addresses are the best identifier, but far from perfect.

In reply to a post by meldrew:

Apparently Digital Spy ban people on the basis of their IP address and then link it to the user name. Clearly it is possible to get them mixed up.

DS banning people? Wow. There's a novelty

This was not a case of "spoofing", there is not much point spoofing the source address of a TCP connection. As he suggested it looks like he unfortunately ended up with the same dynamic IP of a banned member after reassignment.

Same IP but *not* at the same time. Unles you are on a fixed IP then the it's just one of a pool of addresses allocated to an ISP (isn't it?)

That is opinion. Not fact.

I'd have to agree with Spud2003, spoofing is pretty much impossible with TCP since it's like holding a telephone conversation where the replies are sent to someone else's telephone, and the connection has to be established in the first place via a three-way handshake, SYN, SYN-ACK, ACK. TCP connections are well protected against spoofing.

In reply to a post by longedge:

Same IP but *not* at the same time. Unles you are on a fixed IP then the it's just one of a pool of addresses allocated to an ISP (isn't it?)

Yes, but once it's banned the website has no way of knowing when the IP address changes hands.

Edited by Oliver341 (Wed 06-Apr-16 13:06:06)

In reply to a post by Oliver341:

Yes, but once it's banned the website has no way of knowing when the IP address changes hands.

Banning by IP is a bit like using a sledgehammer to crack a walnut. Its a blunt instrument that shouldn't be used - banning by user name makes more sense.

as more and more people use mobile devices and come through Carrier Grade NAT gateways, the number of IP addresses that websites see will be reducing - so a few thousand users behind one or two IPs is going to happen.

This was a problem back in 1999/2000 when NTL users were all behind HTTP proxy caches, and so websites only saw the IP of the proxy cache.

IP address is not user identifying.

In reply to a post by jchamier:

Banning by IP is a bit like using a sledgehammer to crack a walnut. Its a blunt instrument that shouldn't be used - banning by user name makes more sense.

But then people just keep creating new user names to evade the blocks.

In reply to a post by Oliver341:

In reply to a post by jchamier:

Banning by IP is a bit like using a sledgehammer to crack a walnut. Its a blunt instrument that shouldn't be used - banning by user name makes more sense.

But then people just keep creating new user names to evade the blocks.

The forum people can use the IP to see the same username from the same machine in a short period.

In short, the forum owners need to do more effort as I'm sure Seb and John do here.

In reply to a post by jchamier:

The forum people can use the IP to see the same username from the same machine in a short period.

But as you rightly say, IP addresses are dynamic in many cases so the user could switch IP address before creating each user name, usually it's just a matter of pressing disconnect/connect in the router and takes all of 5 seconds. There's only so much that can be done.

Edited by Oliver341 (Wed 06-Apr-16 16:54:55)

Agreed but blocking by IP will become farcical in the future and by banning an IP boards risk banning entire ISPs.

Bad news for advertising revenue.

In reply to a post by RobertoS:

That is opinion. Not fact.

Sorry, you need to read up on the difference between TCP and UDP and where faking the source address is useful and where it is not. If you faked the source address of an attempted TCP connection there would not be any successful connection, it doesn't matter with UDP since it is connectionless, "fire and forget", which is why it is used for DOS and the source address can be faked.

The article you linked to will just confuse the OP and give him the wrong idea.

Accepted . I wasn't thinking straight.

I can't edit or delete it of course, but I expect the OP will already have discounted my post, and certainly will if he reads this.

Assuming ipv6 does eventually get properly rolled out across all users and servers then blocking by ip would become more feasible - mainly because there are enough ipv6 addresses that static ips could be assigned to every home network (or even every device).

In reply to a post by ian72:

Assuming ipv6 does eventually get properly rolled out across all users and servers then blocking by ip would become more feasible - mainly because there are enough ipv6 addresses that static ips could be assigned to every home network (or even every device).

Yes theoretically possible....!