diff --git a/arch-install.md b/arch-install.md
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new mode 100644
diff --git a/arch-post-install.md b/arch-post-install.md
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diff --git a/criptsetup.md b/criptsetup.md
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diff --git a/dwm.md b/dwm.md
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diff --git a/iptables.md b/iptables.md
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index 0000000..38d8d0b
--- /dev/null
+++ b/iptables.md
@@ -0,0 +1,39 @@
+# Iptables.
+
+## Allow ssh traffic.
+~~~
+iptables -A INPUT -p tcp --dport=22 -j ACCEPT
+
+# -A  Append (End table) | -I Insert (Start table).
+# -p  Protocol.
+# -j  Action.
+~~~
+
+## Allow localhost traffic.
+~~~
+iptables -A INPUT -i lo -j ACCEPT
+
+# -i  Interface name.
+~~~
+
+## Allow ping.
+~~~
+iptables -A INPUT -p icmp -j ACCEPT
+~~~
+
+## Warning!!!.
+~~~
+iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
+~~~
+
+## Input policy drop.
+~~~
+iptables -P INPUT DROP
+~~~
+
+## Save/Restore rules from file.
+~~~
+iptables-save > ./filename.rules
+
+# iptables-restore < ./filename.rules
+~~~
diff --git a/letsencrypt.md b/letsencrypt.md
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diff --git a/pass.md b/pass.md
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diff --git a/qemu.md b/qemu.md
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index 4187352..1eeadb7
--- a/qemu.md
+++ b/qemu.md
@@ -3,14 +3,15 @@
 ## Install libs.
 
 ~~~
-sudo pacman -S qemu-full virt-manager libvirt
+sudo pacman -S qemu-full virt-manager libvirt dnsmasq dmidecode
 ~~~
 
 ## Configure libvirt.
 ~~~
 
-sudo virsh -c qemu:///system net-autostart default
-# or sudo virsh net-start default
+virsh -c qemu:///system net-autostart default
+
+# or virsh net-start default
 ~~~
 
 ## Create virtual disk.
diff --git a/st.md b/st.md
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diff --git a/touchpad.md b/touchpad.md
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diff --git a/wireguard.md b/wireguard.md
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diff --git a/xorg.md b/xorg.md
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index 3c8c00e..0a6249d
--- a/xorg.md
+++ b/xorg.md
@@ -1,7 +1,7 @@
 # Install.
 
 ~~~
-pacman -S xorg-server xorg-xinit libx11 libxinerama libxft webkit2gtk
+sudo pacman -S xorg-server xorg-xinit xorg-xrandr libx11 libxinerama libxft webkit2gtk
 vim .xinitrc
 > exec dwm
 ~~~