Improve iptables and add port knocking for SSH

iptables/README.md

@@ -1,23 +1,18 @@
-# iptables & ipset
+# Iptables
 
 ```sh
-sudo apt install ipset
-```
-
-```sh
-sudo cp empty.rules /etc
-sudo touch /etc/{default,ipset}.rules
+sudo cp default.rules empty.rules /etc
 sudo cp *.service /etc/systemd/system
-sudo systemctl enable iptables ipset
-sudo systemctl start iptables ipset
+sudo systemctl enable iptables
+sudo systemctl start iptables
 ```
 
-## Presets
+## Apply and Report Rate Limits
+
+The `ratelimit.rules` file adds new chains to
+limit the rate of new connections based on /16 subnets.
 
 ```sh
-sudo ipset restore -f ipset.rules
-sudo iptables-restore -n connection.rules
-sudo iptables-restore -n service.rules
 sudo iptables-restore -n blackwhite.rules
 sudo iptables-restore -n knock.rules
 sudo iptables-restore -n ratelimit.rules

iptables/blackwhite.rules

@@ -2,12 +2,15 @@
 :BLACKLIST -
 :WHITELIST -
 
--A PREROUTING -j WHITELIST
 -A PREROUTING -j BLACKLIST
+-A PREROUTING -j WHITELIST
 
--A BLACKLIST -m set --match-set blacklist src -j DROP
+-A BLACKLIST -s 46.229.160.0/20 -m comment --comment SEMrushBot -j DROP
+-A BLACKLIST -s 114.119.160.0/21 -m comment --comment AspiegelBot -j DROP
 
--A WHITELIST -m set --match-set local src -j ACCEPT
--A WHITELIST -m set --match-set whitelist src -j ACCEPT
+-A WHITELIST -s 127.0.0.0/8 -m comment --comment localhost -j ACCEPT
+-A WHITELIST -s 10.0.0.0/8 -m comment --comment "RFC 1918" -j ACCEPT
+-A WHITELIST -s 172.16.0.0/12 -m comment --comment "RFC 1918" -j ACCEPT
+-A WHITELIST -s 192.168.0.0/16 -m comment --comment "RFC 1918" -j ACCEPT
 
 COMMIT

iptables/connection.rules

@@ -1,6 +0,0 @@
-*filter
-:CONNECTION -
--A INPUT -j CONNECTION
--A CONNECTION -i lo -j ACCEPT
--A CONNECTION -m state --state RELATED,ESTABLISHED -j ACCEPT
-COMMIT

iptables/default.rules

@@ -1,11 +1,15 @@
 *filter
 :INPUT DROP
+:CONNECTION -
 :SERVICE -
+-A INPUT -j CONNECTION
 -A INPUT -j SERVICE
--A SERVICE -p tcp --dport 22 -j ACCEPT
+-A CONNECTION -i lo -j ACCEPT
+-A CONNECTION -m state --state RELATED,ESTABLISHED -j ACCEPT
 -A SERVICE -p tcp --dport 25 -j ACCEPT
 -A SERVICE -p tcp --dport 80 -j ACCEPT
 -A SERVICE -p tcp --dport 143 -j ACCEPT
 -A SERVICE -p tcp --dport 443 -j ACCEPT
+-A SERVICE -p tcp --dport 22222 -j ACCEPT
 -A SERVICE -p udp --dport 53 -j ACCEPT
 COMMIT

iptables/ipset.rules

@@ -1,8 +0,0 @@
-create local hash:net
-create whitelist hash:net
-create blacklist hash:net
-
-add local 127.0.0.0/8
-add local 10.0.0.0/8
-add local 172.16.0.0/12
-add local 192.168.0.0/16

iptables/ipset.service

@@ -1,13 +0,0 @@
-[Unit]
-Description=ipset
-Before=network-pre.target iptables.service
-Wants=network-pre.target
-
-[Service]
-Type=oneshot
-ExecStart=ipset restore -f /etc/ipset.rules
-ExecStop=ipset save -f /etc/ipset.rules ; ipset destroy
-RemainAfterExit=yes
-
-[Install]
-WantedBy=multi-user.target