Kitz Forum
Computers & Hardware => Networking => Topic started by: tickmike on February 02, 2018, 06:37:26 PM
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Is it possible to have Two Different IP Address's on one computer.
Problem on my new backup server the network card is on a DMZ from my hardware firewall, 176.16.0.1 range on a dedicated port, No normal Internet access .
I want to be able to do the operating system updates.
So could I have a plug in WiFi dongle on IP = 192.168.0.1 range ? .
I do not want to keep changing the adapters config.
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Is it possible to have Two Different IP Address's on one computer.
Yes.
Just remember that the one configured for Internet access should be defined as the default gateway.
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Hi
I hope you don’t mind, but your server should still be able to access updated normally
Dmz does not stop internet access, it removes all barriers from the router/firewall that could potentially stop any traffic.
Be very careful with dmz to anything. In a commercial environment we never dmz anything but setup rules for only that’s needed
Many thanks
John
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It worked ok, There is a convenient USB socket on the top on the server case so I plugged the WiFi dongle into that, configured it and up-dated the server OS updates then un-plugged it until next time, I will not leave it plugged in .
@ d2d4j John will send a pm.
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btw in ipv6 you routinely have lots of ip addresses per nic. On any box if you have more than one nic, then you will always have at least one ip address per nic, so you are bound to have multiple ip addresses.
My ipad has two ipv4 addresses, one for the wi-fi nic and one for its 3g nic. It also has several ipv6 addresses for the wi-fi nic, including a link-local one (unique and meaningful only within the one wireless lan) and several global public routable ones that are valid on the internet. My router has three ipv4 addresses, two for its inwards-facing lan nic, one of which is global public routable is what all the boxes on the lan use normally, and the other extra one is just for admin convenience because it's fixed and memorable at 10.0.0.254 and is only used within the lan for easy admin access, it's easier than remembering the real static value. It also has an ipv4 address for its outward-facing dsl interface, which is also global public routable and static. It has one global routable public static ipv6 address which is for the lan i/f, and probably a link-local ipv6 address for that i/f too.
It's unusual to set multiple ipv4 addresses for the same single nic, and some old machines perhaps can't really deal with it very well. A windows box can have extra ipv4 addresses added to an i/f eg by using the netsh command. A modern o/s just works out what to do with them all and uses the right source ip address when it's talking to some other machine according to context. There is some well defined thing for ipv6 called the source address selection algorithm and this has been back-ported to ipv4 too I believe in post-winxp windows NT-family operating systems, so that it picks sensible source ip addresses that will work in a particular range of ips attached to whichever i/f and it will reply to incoming messages using the src ip that the sender expects, not some other random one that it owns but which will confuse the original sender.
Unfortunately a lot of machines don't know what to do with the various special ipv4 address ranges such as (possibly) 169.254.x.x (link-local) or the rfc1918 private ranges eg 192.168.*.*/16 10.*.*.*/8 and (the /12 one whatever that is) and don't know whether they are useful for internet access because they are NATed, or not and so should be dispreferred. This situation is as it is with ipv4 because these were thought up way too late in the history of the internet and software was already set in its ways. But with ipv6 the link-local address range and other special address ranges were defined right from the start so all software understands what to do and what not to do with these addresses. So no one ever tries to do something stupid like sending to the internet with an fe80::/10 source ip address because that is link-local so meaningful on the current lan, not beyond, and also every interface you have could [in theory] have the same duplicate ipv6 addresses from in that range. (Because fe80 ipv6 addresses are not unique they have labels attached to them within the o/s called scope identifiers which tell the o/s which i/f you are talking about, written as a %n suffixed on the end of the ipv6 address where n is eg 1 2 3 some simple [low] interface-number. It then knows which interface you are talking about if you mention an ip address complete with %n on the end eg fe80::b011:0c5%8)