Helping people with computers... one answer at a time.
DSL modems are typically provided by your ISP. Most people don't realize that you can often purchase your own ... but should you?
What opinion do you have about buying a modem instead of using one supplied by the ISP. Presently I use a dsl modem supplied by my phone co. which is also my ISP. Somewhere in my web rambling I read that modems seem to invite spies, malware and viruses. I don't know how but that's what i think the writer said. As I've been perusing today's newsletter I also see that you mention that it's feasible for people to see our internet addresses if two PC's are behind the same router,which mine are. Do you have any feelings or fears about such things? One thing I don't like about my modem is that the default address of the modem must always remain the same. I am thinking that perhaps with a different modem I could have some leeway in changing the address from time to time as I do with my router.
There's a fair amount of confusion evident in the question, because the modem isn't really related to many of the things mentioned. That's fine, and I'll do my best to clear that up.
Purchasing a modem, rather than using the ISP provided one, isn't all that common but can occasionally be useful. In fact, I had at least one case where I actually had to buy my own. On eBay, no less.
A modem - short for modulator/demodulator - is simply a device that converts one type of electrical signal to another. Originally, it was specifically used for dialup where electrical signals used to connect to your computer were converted, or "modulated", into sounds or audio signals that could go over regular telephone lines. The reverse, listening for incoming audio signals and "demodulating" or converting them to the electrical signals used by the attached computer was the other half of the job.
Very, very technically they're not modulating and demodulating quite the same way any more, but the concept still applies. These days your modem probably takes one type of signal as input - an Ethernet connection - and acts as a converter between that and the DSL signal that travels on your phone line.
But that's really all a modem is - a glorified signal converter that's just a part of getting your computer physically connected to your ISP.
There's nothing about a modem that might "invite spies, malware and viruses". It's hard to even explain why, other than to say that the very concept doesn't apply. I suppose just connecting to the internet is a kind of invitation, but the modem neither helps nor hinders malware any more than valid internet traffic. It's just a conduit.
Similarly, when you connect to your ISP, you are assigned an IP address. That IP address is either assigned to one computer, if you're not using a router, or to the router if you are. All the computers you might have connected to that router have local IP addresses that are not visible on the internet. When any of those computers access the internet they all look like they're at the same internet IP address assigned by your ISP.
Your modem didn't play a role in that. Again, it's just a conduit getting your computer or router connected to your ISP.
Changing your modem - or your router for that matter - will probably not have any affect on your IP address. Certainly powering off your modem might cause the next IP address you're assigned to be different - or not. It all depends on how your ISP assigns and re-uses IP addresses.
Having the same IP address for a lengthy period of time shouldn't make you uncomfortable, either. Most people have them for months, or, in my case, years since I've specifically been assigned an unchanging or "static" IP address. Without a court order your IP address actually tells very little about you. (And with a court order it probably wouldn't matter if your IP was changing frequently.)
Now, there is one potential point of confusion: so far I've talked about modems and routers being separate devices, and usually they are.
But sometimes they're not.
Occasionally some models will also include the functionality of a router.
Nothing in my discussion above changes: it's not inviting malware, and it has no additional impact on how often your internet IP address changes. It just means you don't need an additional router.
So, what about buying your own?
In short, I wouldn't unless there was a reason you needed to.
By using your ISP's modem you're getting their support, and a guarantee that if something changes they'll be responsible to replace the modem as needed. And yes, things do change - not all DSL is the same, and if you do purchase a modem of your own you'll need to make sure it's compatible with your ISP's system.
In my case, my ISP was transitioning its technology, and when my modem failed they no longer had replacements for it. I was on some old DSL technology, but they couldn't provide me a modem to be used with it. (What's worse is that technically with the new technology I was also no longer eligible for service being slightly too far away, so they couldn't just upgrade me.)
That's why I landed on eBay, desperately searching for a replacement modem. (Which I found.)
That's also in part why they're no longer my ISP.
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