[Dnsmasq-discuss] Hello! Also, question about /etc/ethers and /etc/hosts

[Matus UHLAR - fantomas]

Hello,

I use dnsmasq partly because it's lightweight DNS server, partly because 
most of router firmwares provide it as DNS/DHCP server.

On 13.09.23 20:18, TRUNKLES via Dnsmasq-discuss wrote:
> I'd like to start by just asking a simple question I've not managed to find 
> an answer to anywhere else: are /etc/ethers and /etc/hosts supposed to 
> supersede dynamic IP allocaiton?

I don't think anything is supposed to supersede dynamic allocation.
I use /etc/hosts and /etc/ethers as a bit more universal way to achieve 
static DHCP allocation.

the upside is that /etc/hosts is used by system libraries to resolve hosts 
even if DNS is not running.

> Suppose I have all of my "known" devices (MAC addresses) in /etc/ethers, 
> are those supposed to appear to dnsmasq as implicit --dhcp-host= 
> declarations, to take precedence over dynamic host IP allocation as 
> provided by --dhcp-range= statements in the conf file?

I am sure both hosts/ethers and --dhcp-host declaration override dhcp-range, 
because dhcp-range is only to be used for hosts undefined in the above.

I'm not sure whether --dhcp-host overrides /etc/hosts and /etc/ethers, but 
logically I'd expect that explicit dnsmasq configuration would override 
system settings.

> And as for the things that don't work at all part: As deployed, probably 
> badly configured by me, dnsmasq is apparently recognising the /etc/ethers 
> entry and matching it with /etc/hosts, because that shows up and looks 
> good in /var/lib/misc/dnsmasq.leaes, but then, also allocating it a 
> dynamic IP address, which results in entries like this:
>
>1694633632 41:c4:b7:ff:16:a3 192.168.111.126 192.168.111.20 # media-server *
>
> That not only looks wrong, but is wrong enough that if I stop dnsmasq and 
> then restart it, it refuses to run until I've deleted that file.  Clearly, 
> I've done something terrible somewhere, but I still find it interesting 
> that dnsmasq would produce a lease file that is so wrong that it segfaults 
> upon trying to read it back upon restart.

yes, this looks wrong. web search for dhcp.leases file format returns:

https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2006q2/000732.html

However I have no idea how you came to this problem, you should have version 
2.86 installed:

https://packages.ubuntu.com/search?keywords=dnsmasq

Are you sure that only dnsmasq modified dhcp.leases file?

-- 
Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
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