ISP address with cable connection

[MARKBLACK]

Hi I have just received this letter this morning from my ISP

*Thank you for your letter regarding your Internet service.
IP addresses are assigned each time your equipment searches for a connection. With conventional dial up this will be quite often.

As Broadband is constantly connected, your IP address will change less frequently.

In light of this it may be advisable to switch off your modem periodically,for example at night-time, thus creating a new IP address.
I hope this helps you with your query.*

Just wondering how much truth is in it.

MB

[Rick]

I’ve had the same IP address for months now
I never turn off the Modem except when there is a problem

Many cable modems get a new lease on life from the server ever 24 hours
The lease is for 24 hours at a time.

When you turn off the modem it gives up that IP address making it available to the next request for an address

If you are worried about maintaining the same address
Then By all means turn off the modem at night and
LEAVE it off for an extended period of time ( More than 1 Hour)


You can also release the IP ADY manually under the connection properties.
Then wait for an extended period of time before requesting a new ady
This is best done during the day when the network is busy to ensure you get a new one

[MARKBLACK]

I turn my machine off each night and end up with the same IP address the next day, Ive had the same address for 9 - 10 months, I want a different one each day for safety reasons. How do I release the IP ADY manually under the connection properties?

MB

[Budfred]

When you turn your machine off, do you also power off your modem??

[MARKBLACK]

Yes I turn the modem off I'm very safety midded.

below is three different dates the machine/modem was turned off each night. why dosen't the IP address change

May 6: 62.254.91.54

July 7: 62.254.91.54

October 4 62.254.91.54

[ErnieK]

Depending on the type of address your ISP supplies you with you will either have a static address.

With this type you retain the one address no matter whether you turn off or not. You could turn of 100 times a day if you wanted and you still retain the IP address.

or a DHPC (dynamically hosted)
(I think that is the correct name, if I am wrong - which I more than likely am - someone will put me right)

This type means that every time you connect to the net your are given a different IP address set by your ISP.

[MARKBLACK]

right this is how I see it, Ive always thought of *dial-up* being a service that the IP addres changers when you redial.

And the *cable modem* (connected all the time unless the modems disconnected) (broadband) as a static IP address I was confused when I contacted my ISP to be told once the modems been turned off a new IP address in given. I have monitored this for a couple of months so I know it hasn't changed. I just need more proof to tackle them again.

This is why I contacted you guys on here. I was very surprized to hear that Static IP address change when the modems turned off. where do I stand now.

MB

[MARKBLACK]

Ive checked the network connections and its set to obtain IP address automatically. I have a feeling my ISP has picked one for me to use and this one I get and keep all the time.

BTW I can't find anywhere, were it says DHPC

[david eaton]

DCHP actually, but I can't remember what it stands for!

David

[ErnieK]

The following link will explain what it is.

http://www.dhcp.org/

My ISP has three (3) types of Broadband connection.
1 = Static -- ALWAYS the same (least secure as it is always the same and can be watched for specificaly by someone unless you use a router with firewall)

2 = Dhcp -- DIFFERENT every time connection happens (this is the most secure as it is always different)

3 = Do not know name of -- Alterneting IP address within a set of about three IP addresses - every so often IP address will change to another within this set block - depending on how many users are surfing at the time. (in between the above two)

These are my explanations of them

[classicsoftware]

If you have a cable modem, the reason you have it is speed. You don't have to dial in and get an IP address from the ISP, it's always there. The ISP leases the IP addresses and you can have the same one for months before it expires as your earlier post demostrated. If you don't want to do this, get DSL or go back to dial up.

I never turn my modem off and I rarely ever turn my computers off.


If you want to be sevure get a nice Linksys router wich will act as a hardware firewall and prevent most creepy crawlers from getting at your computer from the outside. In addition, also get a software firewall like zone-alarm in case some creepy crawler gets behind the firewall, the software firewall will inform you and you can take appropriate action.

Don't expect the cable company to change the way they do things for your conevenience.

By the way, I've had the same IP address for 3 months, but you cant depend on it for things like remote control. If you do, they will change it and you will be screwed.

To test your system:

Go here

[MARKBLACK]

classicsoftware.

(Don't expect the cable company to change the way they do things for your conevenience.)

I don't expect the cable company to change anything, I want them to abide by their rules I was told my IP address would change every couple of months and it hasn't. I was happy with the dial-up they pestered me to change they said it would be better and safer I beleived them, one has to once in a while. I pay for a service I want that service.
MB

[classicsoftware]

It DOES NOT matter if your IP address changes every day or every month or every minute. If you do not have a firewall hardware & or software, you are not safe. Changing your IP addrres every day provides NO safety at all.

By the way, did you test your system at GRC?

[pave_spectre]

DHCP = Direct Host Configuration Protocol
Used so that administrators of large networks do not need to manually assign potentially hundreds even thousands of machines with IP addresses. Also allows more machines than there are available addresses to be used (obviously not all at the same time).

Strange as it may seem it is also possible to configure the DHCP server to permanently assign addresses to DHCP configured clients.

It is also possible even without such a configuration for a host to regularly obtain the exact same address via DHCP.
For example, the network segment of the college I attend uses DHCP for the clients. I use the same machine every day and every day it has the same address (I know this for a fact since Im constantly checking IPs so people can ping me and to enable access routers and switches).

The only possible explanation I have for this (dont quote me) is that the DHCP server can remember for a period of time who was assigned what addrress and automatically reassign that address if the user logs on within that time period.

[MARKBLACK]

yeah tested my system PASSED.

MB

[classicsoftware]

Passed as in stealth?????

Are you using a router???

[MARKBLACK]

Yeah passed as in stealth

No router used.

MB

[classicsoftware]

Are you running a software firewall???

If you are stealth, than don't worry about your IP address satying the same...

[MARKBLACK]

I'm running the XP firewall (win XP) I have put a tick in both these boxes Broadband Connection + local area network 2 'internet firewall'
I use to have just the broadband ticked but now Ive done them both.

I'm confused to why XP uses these two items, all I can work out is that ones for the 'broadband' and the others for the 'modem', so these two can work together.

Hope you can understand what I'm saying.
mb

[classicsoftware]

What device are you using to connect the computers VIA a LAN.
Is it a hub? or a router/switch?

[MARKBLACK]

just the plain old Cable modem. cable out of the back of the tower straight to the modem - then coxial cable to the NTL box out the front.

MB

[RCB03]

Hey all! Don't know if this will help but this has been my experience with my ISP here in NC. As long as my cable modem is powered up, my IP address will never change. If the modem is on when the lease expires(every 24 hrs. I think),the same IP will be automatically reassigned to me. As I rarely power down the modem, I have had the same IP for nearly a year now. If the modem is off when the lease expires, the IP that was mine is put into a pool of available IP addresses, but the server still remembers that my MAC addresss(hardware address that never changes) is related to the IP address that is now in the pool. Only if that IP is assigned to another user will my IP change.

I think that most cable modem users are like me and leave it on all the time so no ones IP ever changes. I actually powered down the pc and modem for a week once while on vacation just so no lightning damage could occur while I was away. Even after 7 days I still had the same IP. As long as you keep the OS updated and a good firewall running you should be fine as I have.

[no-mbr]

"yeah tested my system PASSED."

Ignorance IS bliss.....

Well, you're on your way to learning networking. You might want to remember that when people talk about TCPIP, they are talking about dozens of types of networking protocols.

DHCP is one type of TCPIP protocol. HOWEVER, there are many "brands" or flavors or configurations of DHCP, that can make it work differently.

How a computer happens to "get an address" can depend on many different conditions.

Now, if someone would like to add something about how firewalls handle connections that originate from their own address, or what happens when a user installs an active x object or plugin from their browser, by all means please do......"yeah tested my system PASSED."

[juniper]

To renew your IP address you would need to keep your modem off until your ISP's DHCP server reassigns that address to another PC. So turning it off durring the day is the most optimal but not guaranteed also changing your MAC address would work as the DHCP server binds the MAC address to the assigned IP address. ( Note you may have to call ISP to release if changing MAC address) Also if you are looking for security get a device that can NAT or PAT your address like a PIX501 or linksys this is the very easiest form of firewalling as you will use a non routable private address behind the appliance so only the appliance is on the internet and your PC is not unless you use packet forwarding. The PIX is the better with its fixup protocol abilities and PAT'ing flexibilty.

[karatekid3d]

DHCP = DYNAMIC HOST CONFIGURATION PROTOCOL