Fix one different IP for each wifi network

<< different configuration profiles for different networks. >>

oh, you need network locations:

Use network locations on Mac - Apple Support

bhavasam wrote:

Thank you, but it seems like I didn't explain myself properly.

I connect to different Wifi networks. For some of them, I need to have a fixed IP, because I use my machine as a server. So, for my home network, I need to be 192.168.0.10, but when I go outside and connect to a restaurant Wifi, I can't use that same IP, so I need to let the DHCP server assign me an IP automatically. The problem is, I haven't been able to find how to set up different configuration profiles for different networks. There seems to be only one window for your Network Settings, shared across all the networks, which you can imagine is a bit of a pain in the *** because every time I hop networks I have to configure the IPs again, and sometimes it might take 20 or 30 minutes of troubleshooting why my networks doesn't have Internet Access until I remember that I have assigned a fixed IP.

How can I do this in MacOS? I want some networks to give me a fixed IP, and others to just assign based on available IPs by the DHCP server

Your current approach seeks to have the network world bend to your will, and that seldom works out.

The IPv4 network design you envision is not going to be portable across networks not cooperating for the management of your IPv4 (or various IPv6) client. You may well disrupt local networking activity with errant IP address assignments or ARP shenanigans, too. Whether that is attempting 0.0.0.0 as you seem to have tried, or some other multicast address, or conflicting with the IP of some locally-important network gear or server.

For networks that are cooperating, the DHCP server can be configured to vend a specific and consistent network-locally-appropriate IP address. You can’t control this assignment from the client, but the DHCP server administrator can control it from the DHCP server.

You might conceivably be able to use a global-scope IPv6 address here, but I’d wager more than a few small networks don’t play well with routing globally-scoped IPv6. And whether your apparently-wants-fixed-IPv4 local apps and services know from IPv6?

There are quite possibly other impediments awaiting for your portable-server design too, including the need for proper reverse DNS for some authenticated network services. Some DNS and DHCP servers can cooperate to provide this, though most small networks are not running authoritative DNS services.

Pragmatically, you’re going to need to fix whatever of your local services expect fixed IP addressing, migrating to using some other means of locating and connecting. That might be switching to a 127/8 address, or maybe running some entirely-local authoritative DNS server, or otherwise. Probably the easiest is to stuff all your client and server giblets into a VM guest, and NAT it all within your own little private fixed-address network universe. This if you want a “roaming” server.

And some questions:

Details of whatever local network services are getting tangled would be interesting.

Which particular network services?

Can DDNS (potentially) work?

PS: you’re definitely not going to get the same IPv4 subnet address assignment across disparate networks; a “globally fixed private IPv4 address’, as it may.

the way your devices are designed to operate on typical networks is to rely on Dynamic Host Configuration Protocol (DHCP) to assign a temporary and strictly-local IP address for each device.

These address are provided by the Router/Gateway for the network. This is generally the default, unless you have changed this by modifying parameters in your main Router.

each Mac is then set to Configure TCP-IP v4 addresses via [__Using DHCP ]

a complete elaboration would require writing a small booklet.

MUCH more information is available about any facet, just ask.

bhavasam wrote:

Hi! I need to set up a different fixed IP for the Wifi networks that my laptop connects to. I used a fixed IP at home and all my devices expect the IP to be the same, but when I go outside I have to change that IP and it becomes a burden having to do this two or three times per week.

Please teach me how can I fix my IP only for one network. Thanks!

I'm confused by what you are requesting.

FYI, you can only control the IP address used by your devices on a network that you control & manage.....such as your own home network. You cannot control the IP address of your Mac when connected to anyone else's network.

You should review the following article & post a clarification of exactly what you are doing & trying to achieve since after reading your post multiple times I still don't understand.

Writing an effective Apple Support Communities Question - Apple Community

When a device (such as a Mac) starts up using DHCP, it gives itself a "self-assigned" pseudo-random identifier so that it can be uniquely addressed on the local network. These address are from a specific range of non-routable reserved IP address that start with 169.254.xxx.yyy

Then it broadcasts request for a valid local IP address from the nearest DHCP Server (typically your MAIN Router). The router responds with an address for that device to use and some DNS numbers and the device substitutes them for defaults. they assignment is called a "lease' and typically alsyts for about a day and s the renewed.

When you find a device that still has its "self-assigned" IP Address, it is an indication that "no one will talk to me" and give me a better, more usable IP address.

the IP address dispensed by DHCP are from a reserved set of "strictly-local" private IP v4 addresses:

192.168.0.0 – 192.168.255.255

172.16.0.0 – 172.31.255.255

10.0.0.0 – 10.255.255.255

these addresses are not valid on the Internet at large, and are unreachable from the internet.

Your Router 'acts as your agent' when talking to the Internet, and does Network Address Translation (NAT) substituting its own Internet-accessible IP address for the local addresses in all transactions.

When information comes back from the Internet, and seems destined for a specific local device, your Router applies a state-wise firewall. Only legitimate responses to queries that each device appears to have made are actually forwarded to your devices. All unsolicited queries are discarded by default.

bhavasam wrote:

How can I do this in MacOS? I want some networks to give me a fixed IP, and others to just assign based on available IPs by the DHCP server

You cannot control the IP given to you while you are using other people's networks unless that network's administrator assign's your device a specific reserved IP address. Public WiFi networks typically use DHCP to dynamically provide devices with an IP address & you should not be assigning yourself a specific IP address....each time you use that public WiFi you will likely receive a different IP Address depending on the lease times of that DHCP server.

First, do you know what IP address you used, so that you never do that again?

try turning Wi-Fi off to regain control. Use the Wi-Fi icon in the menuBar if you can't get into settings.