commit 869384b30bbfac68d58bb04d45cb312b908b2940
parent 98b13422dc49c46e5a92b9d2cae676005b93e968
Author: pyratebeard <root@pyratebeard.net>
Date: Sun, 5 Feb 2023 23:40:58 +0000
Merge branch 'masq_of_the_dhcphantasm'
Diffstat:
1 file changed, 52 insertions(+), 0 deletions(-)
diff --git a/entry/20230205-masq_of_the_dhcphantasm.md b/entry/20230205-masq_of_the_dhcphantasm.md
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+The other day I wanted to test a new network device without connecting it to my home LAN. I knew the device was preconfigured to use DHCP so I very quickly set up one of my laptops as a DHCP server using [dnsmasq](https://dnsmasq.org/){target="_blank" rel="noreferrer"}.
+
+After making sure the `dnsmasq` package was installed on the laptop I disconnected it from the WiFi and plugged it into a switch.
+
+Configuring a static IP differs from system to system, but in this case I was using `netctl`. I took a copy of the example configuration file, /etc/netctl/examples/ethernet-static, put it into the /etc/netctl directory, and changed the 'Interface' and 'Address' variables
+```
+Description='A basic static ethernet connection'
+Interface=enp0s25
+Connection=ethernet
+IP=static
+Address=('192.168.1.1/24')
+#Routes=('192.168.0.0/24 via 192.168.1.2')
+Gateway='192.168.1.1'
+DNS=('192.168.1.1')
+
+## For IPv6 autoconfiguration
+#IP6=stateless
+
+## For IPv6 static address configuration
+#IP6=static
+#Address6=('1234:5678:9abc:def::1/64' '1234:3456::123/96')
+#Routes6=('abcd::1234')
+#Gateway6='1234:0:123::abcd'
+```
+
+Bringing the interface up with
+```
+sudo netctl start ethernet-static
+```
+
+The dnsmasq configuration file is usually /etc/dnsmasq.conf, or you can drop your own config files into /etc/dnsmasq.d/ (ensure you uncomment the include line in /etc/dnsmasq.conf).
+
+My setup was very simple
+```
+# specify ethernet device to operate on
+interface=enp0s25
+
+# disable dns
+port=0
+
+# configure dhcp range and lease time
+dhcp-range=192.168.1.10,192.168.1.12,8h
+```
+
+I didn't need to set a netmask as I am putting the DHCP server (my laptop) in the same range. Before starting `dnsmasq` it is a good idea to validate the configuration
+```
+dnsmasq --test
+```
+
+After starting the `dnsmasq` service I could plug my network device into the router and monitor for any assigned IPs in the file /var/lib/misc/dnsmasq.leases.
+
+There is much more you can do with `dnsmasq` if you want to use it for DHCP properly, but this shows how quick it can be to run it on a LAN or lab environment.
