I have two Pi systems on my LAN here at home, one just provides DNS using dnsmasq and the other has a big external USB drive for backups. The DNS Pi has a static IP of 192.168.1.2. If the DNS Pi dies I want to quickly configure the backup Pi to provide DNS. The main thing required for this to work is to give it a static IP of 192.168.1.2 and to configure dnsmasq on it. Copying the dnsmasq configuration across is easy enough, I can simply synchronise /etc/ and /etc/dnsmasq.d between the two systems and that's done. As long as I don't actually run dnsmasq on the backup machine all will be well. So, if/when the DNS Pi dies all I need to do is:- Configure the backup machine to have a static IP of 192.168.1.2 Copy the dnsmasq.leases file (I'm keeping a live copy of that) Start dnsmasq Simple! :-) Is the configuration in /etc/ *all* that's needed for a static IP? -- Chris Green

I'm always cautious of configuring any computer with a static IP address in the device's TCP configuration. It's all too easy to move a portable device onto a different LAN where the static IP may either be in the wrong subnet or may be within the scope of the LAN's DHCP server and so may, when Sod's Law is in operation, give another device the same address. Instead, I configure the router to allocate a reserved address (as an IP-to-MAC address mapping) for the devices that I want to have a "static" address. Most modern routers seem to allow reserved IPs to be configured. There is no need for the reserved addresses to be outside the scope of addresses that DHCP hands out. So you are using DHCP in exactly the same way as a normal (random-IP) setup, but forcing the router's DHCP to give certain devices fixed addresses. In your situation where you want either the main or the backup Pi to have the same IP, you could achieve this by tweaking the router's reserved addresses....

Do I just need to change dhcpcd.conf to get a static IP?

Sep 28, 2021 22 Replies

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The Natural Philosopher 4 years ago

I cannot but agree. In the end I ended up with a S/H Cisco SOHO router - rebadged linksys I think - which was reliable but too much of a room heater and replaced it with a draytek, which has been 100% reliable, but

if you need the internet thats only a few months broadband bill. I've had D link, Netgear and TP-link routers too - all have been at one time or another replaced due to flakiness.Ive got a Netgear whose ADSL performance went suspect after a thunderstorm in use as a WAP. It still isn't 100% reliable.

The use of BIND on root hints seems fine to me. DNS was never a huge network or CPU load. And it allows you to fully control DNS.

The lifetime of any political organisation is about three years before its been subverted by the people it tried to warn you about. Anon.

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Joe 4 years ago

+many for Draytek. I've also had a variety, of which Netgear (one of the many DG834s) was about the least bad, but the Draytek Vigor was easily way ahead of them all, only being abandoned when I went to FTTC. Many more facilities and somehow, a more professional configuration menu.

Joe

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Ahem A Rivet's Shot 4 years ago

These days my router is a refurbished office PC with a decent dual port NIC (as well as the onboard one) running FreeBSD. It's overkill (especially the 8Gb of RAM) but it handles PPPoE at gigabit speeds without breaking a sweat, is rock solid reliable and runs software I understand.

Steve O'Hara-Smith Odds and Ends at http://www.sohara.org/

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