diff --git a/knowledge base/turris.md b/knowledge base/turris.md
index db6d996..511e460 100644
--- a/knowledge base/turris.md	
+++ b/knowledge base/turris.md	
@@ -18,6 +18,9 @@
 uci show
 uci show 'dhcp'
 
+# Show what interface is the WAN.
+uci show network.wan.device | cut -d "'" -f 2
+
 # Configure a static IP address lease.
 uci add dhcp host
 uci set dhcp.@host[-1].name='hostname'
@@ -197,6 +200,7 @@ Most compatible upgrades are available on [Discomp].
 
 - [Led settings][wiki led settings] on the [wiki][turris wiki]
 - [opkg]
+- [uci]
 - [Supported SFP modules]
 
 ## Sources
@@ -217,6 +221,7 @@ Most compatible upgrades are available on [Discomp].
 
 <!-- internal references -->
 [opkg]: opkg.md
+[uci]: uci.md
 
 <!-- external references -->
 [discomp]: https://www.discomp.cz/
diff --git a/knowledge base/uci.md b/knowledge base/uci.md
new file mode 100644
index 0000000..f630e1b
--- /dev/null
+++ b/knowledge base/uci.md	
@@ -0,0 +1,40 @@
+# uci
+
+Command line utility for OpenWrt's UCI system.
+
+## TL;DR
+
+```sh
+# Show settings.
+uci show
+uci show 'dhcp'
+
+# Show what interface is the WAN.
+uci show network.wan.device | cut -d "'" -f 2
+
+# Configure a static IP address lease.
+uci add dhcp host
+uci set dhcp.@host[-1].name='hostname'
+uci set dhcp.@host[-1].mac='11:22:33:44:55:66'
+uci set dhcp.@host[-1].ip='192.168.1.2'
+
+# Show changes to the settings.
+uci changes
+uci changes 'dhcp'
+
+# Commit changes.
+uci commit
+uci commit 'dhcp'
+```
+
+## Further readings
+
+- [The UCI system]
+
+## Sources
+
+<!-- project's references -->
+[the uci system]: https://openwrt.org/docs/guide-user/base-system/uci
+
+<!-- internal references -->
+<!-- external references -->