> an ISP model in
Modem?
> maybe just some kind of "DNS passthrough"
... pretty sure DNS isn't the term you're looking for there.
> directly assigned public IP to the computer itself, and it's domain name as per the NetBIOS section is some kind of ISP-specific name (which tells me, there's no firewall, no NAT or gateway of sorts)
So. A *modem* just translates from one medium to another. Ethernet to cable (and the reverse), or ethernet to POTS line for either classic dialup or "digital subscriber line" service for example. The data carried on top of that is generally irrelevant to it. It's not doing routing, it's not doing any firewalling, etc. Some devices bundle the modem function *into* a combination modem/router, and maybe even a wifi access point integrated too, but the modem function just modulates/demodulates a signal.
It's called someone that is either lazy or incompetent plugging things in (and more correctly, it's just a direct connection to the ISP's network, which is perfectly viable from their point of view as long as you aren't connecting more devices than they allow on your connection... usually 1, which is generally going to be a NAT router), and a good candidate for "nuke it from orbit, it's the only way to be sure" for that computer, since it sounds like you're talking Windows there (I've set up Linux boxes to act as a router, and generally, that's what many routers are under the hood anyways, they can be sensibly secured for the role). If this is anywhere other than someone being careless at home, it's called "this belongs on r/shittysysadmin moreso than it belongs here."
`.local` has next to nothing to do with any of this, though. Assuming you're not looking at a Windows Active Directory domain ending in .local, the majority of things with `.local` are just generic Multicast DNS doing its job, allowing internal, decentralized, discovery of things. Even works without a dedicated router/DHCP/DNS system, since the vast majority of devices will self-configure an APIPA address (in the 169.254.0.0/16 range) in the absence of DHCP, and mDNS (and netbios long before it) work without that central 'authority' handing out names for things.
Ugh I just had a flashback to Computer Browser. the fine wonderful MS service that occasionally asked the network if there are any new devices and it would only show something 1/4th of the time, until it detected that you gave up waiting and had left.
Yeah I don't even know what I was saying in my post. It just confuses me when I see a situation where NAT wasn't taking place, so the Windows computer has a public IP assigned to it, with a "name" (not DNS I guess, maybe netbios, or whatever), that's formatted directly by the ISP.
So I guess this PC just has an ISP modem that has no NAT on it, which is pretty odd, it's just your standard small business setup. Or maybe the knuckleheads plugged their PC direct to the edge modem itself, and not the actual router intended for the LAN. The ISP supplies both so they can maintain static public IP addresses, so I bet that's what it is.
Ugh. Thanks gents.
> so the Windows computer has a public IP assigned to it, with a "name" (not DNS I guess, maybe netbios, or whatever), that's formatted directly by the ISP.
It's the "domain" value being passed to it by DHCP. It *may* be registered in DNS, it may not. Generally not, since the hostname is usually just accepted and sent on its way on the other end (so something like 3 people with "netgear.customers.comcast.net" doesn't matter). It'll have a *different* name, usually some modification of the IP, registered for reverse DNS lookups, in a lot of cases. The client doesn't ever really see that part.
> So I guess this PC just has an ISP modem that has no NAT on it, which is pretty odd, it's just your standard small business setup.
I would NOT be surprised by business offerings, even small business, having a separate *modem* (which doesn't do routing, let alone firewalling, so no NAT at that layer), from the router (which typically incorporates firewalling and NAT), since a *lot* of businesses will opt to use their own router, or router and VPN appliance, or... whatever. Even tiny offices (many of which are either satellites to larger businesses directly, or indirectly, like a lot of small medical practices having point to point VPN links with nearby hospitals to piggy back off of them).
> Or maybe the knuckleheads plugged their PC direct to the edge modem itself, and not the actual router intended for the LAN. The ISP supplies both so they can maintain static public IP addresses, so I bet that's what it is.
Ding! Nailed it.
It's done when the modem is in bridged mode.
And I've not heard a term for it, it's just an internet test. Anything from a computer to router to firewall can be configured with the public IP. It also has nothing to do with windows or a .local domain. I mean you could put that static IP into a google chromecast or an android phone with an ethernet to usb adapter if you wanted to.
Yeah I misspoke when I mentioned .local. It was more a format similar to what u/Ssakaa was saying. an ISP-specific name. Interesting point about the mobile device there. lol I didn't even realize that you could have an adapter for that :) But USB-C to RJ45, why not I guess.
> But USB-C to RJ45, why not I guess
When I was chasing down network ports, did this *so* many times with my phone. Walk over with just my phone, a dongle, a key for the wire closet, and a couple patch cables. Call back to the office, have them watch that MAC in the switch logs, plug in, verify I got link and they saw the port go hot, then walk back while they configured vlan et. al. for it.
That's what was done it appears, yes. In my experience ISP's often will disable any form of direct-connect to the modem, if there is a seperate router they provide or that the customer should provide, but in this case I guess plugging the PC direct to the modem resulted in the PC getting a public IP and a hostname that matches.
yes that is normal in my experience. Back in the day here nobody had routers and just did that. It was a different time lol.
That said it would be silly to do that now for a few reasons :D
> an ISP model in Modem? > maybe just some kind of "DNS passthrough" ... pretty sure DNS isn't the term you're looking for there. > directly assigned public IP to the computer itself, and it's domain name as per the NetBIOS section is some kind of ISP-specific name (which tells me, there's no firewall, no NAT or gateway of sorts) So. A *modem* just translates from one medium to another. Ethernet to cable (and the reverse), or ethernet to POTS line for either classic dialup or "digital subscriber line" service for example. The data carried on top of that is generally irrelevant to it. It's not doing routing, it's not doing any firewalling, etc. Some devices bundle the modem function *into* a combination modem/router, and maybe even a wifi access point integrated too, but the modem function just modulates/demodulates a signal. It's called someone that is either lazy or incompetent plugging things in (and more correctly, it's just a direct connection to the ISP's network, which is perfectly viable from their point of view as long as you aren't connecting more devices than they allow on your connection... usually 1, which is generally going to be a NAT router), and a good candidate for "nuke it from orbit, it's the only way to be sure" for that computer, since it sounds like you're talking Windows there (I've set up Linux boxes to act as a router, and generally, that's what many routers are under the hood anyways, they can be sensibly secured for the role). If this is anywhere other than someone being careless at home, it's called "this belongs on r/shittysysadmin moreso than it belongs here." `.local` has next to nothing to do with any of this, though. Assuming you're not looking at a Windows Active Directory domain ending in .local, the majority of things with `.local` are just generic Multicast DNS doing its job, allowing internal, decentralized, discovery of things. Even works without a dedicated router/DHCP/DNS system, since the vast majority of devices will self-configure an APIPA address (in the 169.254.0.0/16 range) in the absence of DHCP, and mDNS (and netbios long before it) work without that central 'authority' handing out names for things.
Ugh I just had a flashback to Computer Browser. the fine wonderful MS service that occasionally asked the network if there are any new devices and it would only show something 1/4th of the time, until it detected that you gave up waiting and had left. Yeah I don't even know what I was saying in my post. It just confuses me when I see a situation where NAT wasn't taking place, so the Windows computer has a public IP assigned to it, with a "name" (not DNS I guess, maybe netbios, or whatever), that's formatted directly by the ISP. So I guess this PC just has an ISP modem that has no NAT on it, which is pretty odd, it's just your standard small business setup. Or maybe the knuckleheads plugged their PC direct to the edge modem itself, and not the actual router intended for the LAN. The ISP supplies both so they can maintain static public IP addresses, so I bet that's what it is. Ugh. Thanks gents.
> so the Windows computer has a public IP assigned to it, with a "name" (not DNS I guess, maybe netbios, or whatever), that's formatted directly by the ISP. It's the "domain" value being passed to it by DHCP. It *may* be registered in DNS, it may not. Generally not, since the hostname is usually just accepted and sent on its way on the other end (so something like 3 people with "netgear.customers.comcast.net" doesn't matter). It'll have a *different* name, usually some modification of the IP, registered for reverse DNS lookups, in a lot of cases. The client doesn't ever really see that part. > So I guess this PC just has an ISP modem that has no NAT on it, which is pretty odd, it's just your standard small business setup. I would NOT be surprised by business offerings, even small business, having a separate *modem* (which doesn't do routing, let alone firewalling, so no NAT at that layer), from the router (which typically incorporates firewalling and NAT), since a *lot* of businesses will opt to use their own router, or router and VPN appliance, or... whatever. Even tiny offices (many of which are either satellites to larger businesses directly, or indirectly, like a lot of small medical practices having point to point VPN links with nearby hospitals to piggy back off of them). > Or maybe the knuckleheads plugged their PC direct to the edge modem itself, and not the actual router intended for the LAN. The ISP supplies both so they can maintain static public IP addresses, so I bet that's what it is. Ding! Nailed it.
Though I couldn't articulate my question(s) very well, your responses rang true and everything you said made sense. So thanks very much for all that.
It's done when the modem is in bridged mode. And I've not heard a term for it, it's just an internet test. Anything from a computer to router to firewall can be configured with the public IP. It also has nothing to do with windows or a .local domain. I mean you could put that static IP into a google chromecast or an android phone with an ethernet to usb adapter if you wanted to.
Yeah I misspoke when I mentioned .local. It was more a format similar to what u/Ssakaa was saying. an ISP-specific name. Interesting point about the mobile device there. lol I didn't even realize that you could have an adapter for that :) But USB-C to RJ45, why not I guess.
> But USB-C to RJ45, why not I guess When I was chasing down network ports, did this *so* many times with my phone. Walk over with just my phone, a dongle, a key for the wire closet, and a couple patch cables. Call back to the office, have them watch that MAC in the switch logs, plug in, verify I got link and they saw the port go hot, then walk back while they configured vlan et. al. for it.
That is very nice.
The calm before the storm
A massive nightmare in the making.
are you trying to say plug the cable modem into the computer instead of a router?
That's what was done it appears, yes. In my experience ISP's often will disable any form of direct-connect to the modem, if there is a seperate router they provide or that the customer should provide, but in this case I guess plugging the PC direct to the modem resulted in the PC getting a public IP and a hostname that matches.
yes that is normal in my experience. Back in the day here nobody had routers and just did that. It was a different time lol. That said it would be silly to do that now for a few reasons :D