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IPtables firewall on a router virtual machine running on a remote VMware ESXi host (it ran on Hetzner in this example). It requires a separate subnet, a dedicated vm router IP address and only supports IPv4.
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| #!/bin/bash | |
| ################################################################################ | |
| # 2014-08-03 | Jason Friedrich | |
| #------------------------------------------------------------------------------- | |
| # Version history: | |
| # v1.2 | 2022-06-27 | |
| # - Partial rewrite for net network structure | |
| # v1.1 | 2014-08-03 | |
| # - Complete rewrite for new network structure | |
| ################################################################################ | |
| ################################################################################ | |
| ## VARIABLES | |
| ################################################################################ | |
| ## BINARIES | |
| IPT='/sbin/iptables -v' | |
| ## ROUTER INTERFACES | |
| EXTINT='eth0' | |
| SUBINT='eth6' | |
| ALPHAINT='eth1' | |
| BETAINT='eth2' | |
| SRVINT='eth5' | |
| DOCKERINT='eth3' | |
| K8SINT='eth4' | |
| ## ROUTER NETWORKS | |
| SUBNET='1.2.3.4/29' | |
| ALPHANET='10.20.0.0/24' | |
| BETANET='10.30.0.0/24' | |
| SRVNET='10.200.0.0/24' | |
| DOCKERNET='10.50.0.0/24' | |
| K8SNET='10.60.0.0/24' | |
| ## ROUTER IPS | |
| EXTIP='2.3.4.5' | |
| SUBIP='3.4.5.6' | |
| ALPHAIP='10.20.0.1' | |
| BETAIP='10.30.0.1' | |
| SRVIP='10.200.0.1' | |
| DOCKERIP='10.50.0.1' | |
| K8SIP='10.60.0.1' | |
| ## PUBLIC INTERNET HOSTS | |
| HOMEOFFICE='4.5.6.7/24' | |
| TAILSCALE='xxx.xx.0.0/10' | |
| HETZNERBACKUP='188.40.2.186/32' | |
| HETZNERDNS01='213.133.98.98' | |
| HETZNERDNS02='213.133.99.99' | |
| HETZNERDNS03='213.133.100.100' | |
| QUADDNS01='1.1.1.1' | |
| QUADDNS02='9.9.9.9' | |
| ################################################################################ | |
| ## FUNCTIONS | |
| ################################################################################ | |
| function delfwrules { | |
| ## DELETE ALL EXISTING RULES | |
| echo 'INFO: Deleting all existing firewall rules' | |
| ${IPT} -F | |
| ${IPT} -X | |
| ${IPT} -t nat -F | |
| ${IPT} -t nat -X | |
| } | |
| function enablefwd { | |
| ## ENABLE IPV4 FORWARDING | |
| echo 'INFO: Enabling IPV4 forwarding' | |
| echo 1 > /proc/sys/net/ipv4/ip_forward | |
| echo 1 > /proc/sys/net/ipv4/conf/all/forwarding | |
| #echo 1 > /proc/sys/net/ipv6/conf/all/forwarding | |
| } | |
| function disablefwd { | |
| ## DISABLE IPV4 FORWARDING | |
| echo 'INFO: Disabling IPV4 forwarding' | |
| echo 0 > /proc/sys/net/ipv4/ip_forward | |
| echo 0 > /proc/sys/net/ipv4/conf/all/forwarding | |
| #echo 0 > /proc/sys/net/ipv6/conf/all/forwarding | |
| } | |
| function setdefpol { | |
| if [ "${1}" == "drop" ]; then | |
| ## DEFAULT POLICY = DROP | |
| echo 'INFO: Setting default policy to: DROP' | |
| ${IPT} -P INPUT DROP | |
| ${IPT} -P OUTPUT DROP | |
| ${IPT} -P FORWARD DROP | |
| elif [ "${1}" == "reject" ]; then | |
| ## DEFAULT POLICY = REJECT | |
| echo 'INFO: Setting default policy to: REJECT' | |
| ${IPT} -P INPUT REJECT | |
| ${IPT} -P OUTPUT REJECT | |
| ${IPT} -P FORWARD REJECT | |
| elif [ "${1}" == "accept" ]; then | |
| ## DEFAULT POLICY = ACCEPT | |
| echo 'INFO: Setting default policy to: ACCEPT' | |
| ${IPT} -P INPUT ACCEPT | |
| ${IPT} -P OUTPUT ACCEPT | |
| ${IPT} -P FORWARD ACCEPT | |
| else | |
| ## DEFAULT POLICY = DROP | |
| echo 'WARN: Keyword not identified, setting default policy to DROP' | |
| ${IPT} -P INPUT DROP | |
| ${IPT} -P OUTPUT DROP | |
| ${IPT} -P FORWARD DROP | |
| fi | |
| } | |
| function enablefw { | |
| # enable ip forwarding | |
| enablefwd | |
| # set default policy to drop | |
| setdefpol drop | |
| ################################################################################ | |
| ## BLACKLIST | |
| ################################################################################ | |
| # ${IPT} -A INPUT -i ${EXTINT} -s 37.187.195.49 -j DROP | |
| # ${IPT} -A INPUT -i ${EXTINT} -s 212.156.115.16 -j DROP | |
| # ${IPT} -A INPUT -i ${EXTINT} -s 195.93.172.17 -j DROP | |
| ################################################################################ | |
| ## FAILSAFE RULES | |
| ################################################################################ | |
| ## RELATED AND ESTABLISHED CONNECTIONS | |
| #${IPT} -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT | |
| #${IPT} -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT | |
| #${IPT} -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT | |
| ${IPT} -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT | |
| ${IPT} -A OUTPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT | |
| ${IPT} -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT | |
| ## FAILSAFE SSH | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -s ${HOMEOFFICE} -p tcp --dport 22 -j ACCEPT | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -s ${TAILSCALE} -p tcp --dport 22 -j ACCEPT | |
| ################################################################################ | |
| ## RULES FOR SUBNET | |
| ################################################################################ | |
| ## ALLOW EVERTYTHING IN, OUT AND FORWARD FOR SUBNET | |
| ${IPT} -A INPUT -d ${SUBNET} -i ${EXTINT} -p all -j ACCEPT | |
| ${IPT} -A FORWARD -d ${SUBNET} -i ${EXTINT} -o ${SUBINT} -p all -j ACCEPT | |
| ${IPT} -A FORWARD -s ${SUBNET} -i ${SUBINT} -o ${EXTINT} -p all -j ACCEPT | |
| ${IPT} -A OUTPUT -s ${SUBNET} -o ${EXTINT} -p all -j ACCEPT | |
| ################################################################################ | |
| ## INTERNAL NETWORKS | |
| ################################################################################ | |
| ## ALLOW INCOMING ALL FROM ALPHA NET OVER ALPHA INT | |
| ${IPT} -A INPUT -s ${ALPHANET} -i ${ALPHAINT} -p all -j ACCEPT | |
| ## ALLOW OUTGOING ALL TO ALPHA NET OVER ALPHA INT | |
| ${IPT} -A OUTPUT -d ${ALPHANET} -o ${ALPHAINT} -p all -j ACCEPT | |
| ## ALLOW FORWARDING ALL FROM ALPHA NET INCOMING ALPHA INT OUTGOING EXT INT | |
| ${IPT} -A FORWARD -s ${ALPHANET} -i ${ALPHAINT} -o ${EXTINT} -p all -j ACCEPT | |
| ## MASQUERADE INTERNAL IPS TO ALLOW INTERNET ACCESS FROM INTERNAL NETWORK | |
| ${IPT} -t nat -A POSTROUTING -s ${ALPHANET} -o ${EXTINT} -j MASQUERADE | |
| ## ALLOW INCOMING ALL FROM BETA NET OVER BETA INT | |
| ${IPT} -A INPUT -s ${BETANET} -i ${BETAINT} -p all -j ACCEPT | |
| ## ALLOW OUTGOING ALL TO BETA NET OVER BETA INT | |
| ${IPT} -A OUTPUT -d ${BETANET} -o ${BETAINT} -p all -j ACCEPT | |
| ## ALLOW FORWARDING ALL FROM BETA NET INCOMING BETA INT OUTGOING EXT INT | |
| ${IPT} -A FORWARD -s ${BETANET} -i ${BETAINT} -o ${EXTINT} -p all -j ACCEPT | |
| ## MASQUERADE INTERNAL IPS TO ALLOW INTERNET ACCESS FROM INTERNAL NETWORK | |
| ${IPT} -t nat -A POSTROUTING -s ${BETANET} -o ${EXTINT} -j MASQUERADE | |
| ## ALLOW INCOMING ALL FROM DOCKER NET OVER DOCKER INT | |
| ${IPT} -A INPUT -s ${DOCKERNET} -i ${DOCKERINT} -p all -j ACCEPT | |
| ## ALLOW OUTGOING ALL TO DOCKER NET OVER DOCKER INT | |
| ${IPT} -A OUTPUT -d ${DOCKERNET} -o ${DOCKERINT} -p all -j ACCEPT | |
| ## ALLOW FORWARDING ALL FROM DOCKER NET INCOMING DOCKER INT OUTGOING EXT INT | |
| ${IPT} -A FORWARD -s ${DOCKERNET} -i ${DOCKERINT} -o ${EXTINT} -p all -j ACCEPT | |
| ## MASQUERADE INTERNAL IPS TO ALLOW INTERNET ACCESS FROM INTERNAL NETWORK | |
| ${IPT} -t nat -A POSTROUTING -s ${DOCKERNET} -o ${EXTINT} -j MASQUERADE | |
| ## ALLOW INCOMING ALL FROM K8S NET OVER K8S INT | |
| ${IPT} -A INPUT -s ${K8SNET} -i ${K8SINT} -p all -j ACCEPT | |
| ## ALLOW OUTGOING ALL TO K8S NET OVER K8S INT | |
| ${IPT} -A OUTPUT -d ${K8SNET} -o ${K8SINT} -p all -j ACCEPT | |
| ## ALLOW FORWARDING ALL FROM K8S NET INCOMING K8S INT OUTGOING EXT INT | |
| ${IPT} -A FORWARD -s ${K8SNET} -i ${K8SINT} -o ${EXTINT} -p all -j ACCEPT | |
| ## MASQUERADE INTERNAL IPS TO ALLOW INTERNET ACCESS FROM INTERNAL NETWORK | |
| ${IPT} -t nat -A POSTROUTING -s ${K8SNET} -o ${EXTINT} -j MASQUERADE | |
| ################################################################################ | |
| ## ADMIN / SRV NETWORK ACCESS | |
| ################################################################################ | |
| ## ALLOW ALL INCOMING FROM SRV NET OVER SRV INT | |
| ${IPT} -A INPUT -s ${SRVNET} -i ${SRVINT} -p all -j ACCEPT | |
| ## ALLOW ALL OUTGOING TO SRV NET OVER SRV INT | |
| ${IPT} -A OUTPUT -d ${SRVNET} -o ${SRVINT} -p all -j ACCEPT | |
| ## ALLOW ALL FORWARDING FROM SRV NET OVER SRV INT TO ANY | |
| ${IPT} -A FORWARD -s ${SRVNET} -i ${SRVINT} -p all -j ACCEPT | |
| ## MASQUERADE SRV NET OVER EXT INT TO INTERNET | |
| ${IPT} -t nat -A POSTROUTING -s ${SRVNET} -o ${EXTINT} -j MASQUERADE | |
| ################################################################################ | |
| ## ROUTER VM | |
| ################################################################################ | |
| ## ALLOW INCOMING, OUTGOING, FORWARDING FROM LO OVER LO INT | |
| ${IPT} -A INPUT -i lo -j ACCEPT | |
| ${IPT} -A OUTPUT -o lo -j ACCEPT | |
| ${IPT} -A FORWARD -i lo -o lo -j ACCEPT | |
| ## ALLOW INCOMING USEFUL ICMP TO EXT IP OVER EXT INT | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -p icmp --icmp-type 0 -j ACCEPT -m comment --comment "ICMP Echo Reply" | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -p icmp --icmp-type 3 -j ACCEPT -m comment --comment "ICMP Echo Request" | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -p icmp --icmp-type 8 -j ACCEPT -m comment --comment "ICMP Echo Request" | |
| ${IPT} -A INPUT -d ${EXTIP} -i ${EXTINT} -p icmp --icmp-type 11 -j ACCEPT -m comment --comment "ICMP Time Exceeded" | |
| ## ALLOW INCOMING USEFUL ICMP TO SUB IP OVER EXT INT (STRANGE HETZNER ROUTING) | |
| ${IPT} -A INPUT -d ${SUBIP} -i ${EXTINT} -p icmp --icmp-type 0 -j ACCEPT -m comment --comment "ICMP Echo Reply" | |
| ${IPT} -A INPUT -d ${SUBIP} -i ${EXTINT} -p icmp --icmp-type 3 -j ACCEPT -m comment --comment "ICMP Echo Request" | |
| ${IPT} -A INPUT -d ${SUBIP} -i ${EXTINT} -p icmp --icmp-type 8 -j ACCEPT -m comment --comment "ICMP Echo Request" | |
| ${IPT} -A INPUT -d ${SUBIP} -i ${EXTINT} -p icmp --icmp-type 11 -j ACCEPT -m comment --comment "ICMP Time Exceeded" | |
| ## ALLOW OUTGOING ALL FROM EXT IP OVER EXT INT | |
| ${IPT} -A OUTPUT -s ${EXTIP} -o ${EXTINT} -j ACCEPT | |
| ## ALLOW OUTGOING ALL FROM SUB IP OVER SUB INT, EXT INT | |
| ${IPT} -A OUTPUT -s ${SUBIP} -o ${SUBINT} -j ACCEPT | |
| ${IPT} -A OUTPUT -s ${SUBIP} -o ${EXTINT} -j ACCEPT | |
| ################################################################################ | |
| ## LOGGING | |
| ################################################################################ | |
| # create new rule for loggin | |
| ${IPT} -N LOGGING | |
| # apply rule to all chains | |
| ${IPT} -A INPUT -j LOGGING | |
| ${IPT} -A OUTPUT -j LOGGING | |
| ${IPT} -A FORWARD -j LOGGING | |
| # limit logging | |
| ${IPT} -A LOGGING -m limit --limit 5/min -j LOG --log-prefix "[iptables-dropped]: " --log-level 4 | |
| # only log dropped packages | |
| ${IPT} -A LOGGING -j DROP | |
| } | |
| function disablefw { | |
| disablefwd | |
| setdefpol accept | |
| } | |
| function fwdonly { | |
| enablefwd | |
| setdefpol accept | |
| ${IPT} -t nat -A POSTROUTING -s ${ALPHANET} -j MASQUERADE | |
| ${IPT} -t nat -A POSTROUTING -s ${BETANET} -j MASQUERADE | |
| ${IPT} -t nat -A POSTROUTING -s ${DOCKERNET} -j MASQUERADE | |
| ${IPT} -t nat -A POSTROUTING -s ${K8SNET} -j MASQUERADE | |
| ${IPT} -t nat -A POSTROUTING -s ${SRVNET} -j MASQUERADE | |
| } | |
| ################################################################################ | |
| ## MAIN | |
| ################################################################################ | |
| if [ "${1}" == "enable" ]; then | |
| delfwrules | |
| enablefw | |
| elif [ "${1}" == "disable" ]; then | |
| delfwrules | |
| disablefw | |
| elif [ "${1}" == "fwdonly" ]; then | |
| delfwrules | |
| fwdonly | |
| else | |
| echo "Usage: $(basename \"$0\") enable | disable | fwdonly" | |
| echo " enable: Enable firewall" | |
| echo " disable: Disable firewall" | |
| echo " fwdonly: Forwarding only (default policy: ACCEPT)" | |
| exit 0 | |
| fi |
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