I have setup an access point on my raspberry pi 4 following this guide: https://www.raspberrypi.com/documentation/computers/configuration.html#before-you-begin
I can connect to the wireless network, ping the ip address on the raspberry pi wlan interface, and dns seems to work fine.
But the NAT/routing is not working. I'm unable to access the internet or the rest of my network.
I believe this has something to do with docker and maybe messing up my iptables? But I don't know enough about iptables to explain why it isn't working. This is a dump of the iptables. I see the rule "-A POSTROUTING -o eth0 -j MASQUERADE" was added which should enable the nat routing for my access-point.
# Generated by iptables-save v1.8.7 on Sun Feb 26 12:27:58 2023
*filter
:INPUT ACCEPT [36647:6241476]
:FORWARD DROP [151:15122]
:OUTPUT ACCEPT [34684:33197826]
:DOCKER - [0:0]
:DOCKER-ISOLATION-STAGE-1 - [0:0]
:DOCKER-ISOLATION-STAGE-2 - [0:0]
:DOCKER-USER - [0:0]
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION-STAGE-1
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -i br-ea8912f60ffe -o br-ea8912f60ffe -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.17.0.3/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 9443 -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 80 -j ACCEPT
-A DOCKER -d 172.17.0.3/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 9000 -j ACCEPT
-A DOCKER -d 172.17.0.4/32 ! -i docker0 -o docker0 -p udp -m udp --dport 10001 -j ACCEPT
-A DOCKER -d 172.17.0.3/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 8000 -j ACCEPT
-A DOCKER -d 172.17.0.4/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 8443 -j ACCEPT
-A DOCKER -d 172.17.0.4/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 8080 -j ACCEPT
-A DOCKER -d 172.17.0.4/32 ! -i docker0 -o docker0 -p udp -m udp --dport 3478 -j ACCEPT
-A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 ! -s 172.80.0.0/24 -o br-ea8912f60ffe -j DROP
-A DOCKER-ISOLATION-STAGE-1 ! -d 172.80.0.0/24 -i br-ea8912f60ffe -j DROP
-A DOCKER-ISOLATION-STAGE-1 -j RETURN
-A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -j RETURN
-A DOCKER-USER -j RETURN
COMMIT
# Completed on Sun Feb 26 12:27:58 2023
# Generated by iptables-save v1.8.7 on Sun Feb 26 12:27:58 2023
*nat
:PREROUTING ACCEPT [1508:237688]
:INPUT ACCEPT [1207:192448]
:OUTPUT ACCEPT [15971:766826]
:POSTROUTING ACCEPT [8642:433956]
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 9443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 9000 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 8000 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.17.0.4/32 -d 172.17.0.4/32 -p udp -m udp --dport 10001 -j MASQUERADE
-A POSTROUTING -s 172.17.0.4/32 -d 172.17.0.4/32 -p tcp -m tcp --dport 8443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.4/32 -d 172.17.0.4/32 -p tcp -m tcp --dport 8080 -j MASQUERADE
-A POSTROUTING -s 172.17.0.4/32 -d 172.17.0.4/32 -p udp -m udp --dport 3478 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 9443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 9000 -j MASQUERADE
-A POSTROUTING -s 172.17.0.3/32 -d 172.17.0.3/32 -p tcp -m tcp --dport 8000 -j MASQUERADE
-A POSTROUTING -o eth0 -j MASQUERADE
-A DOCKER -i docker0 -j RETURN
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.17.0.2:443
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 9443 -j DNAT --to-destination 172.17.0.3:9443
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.17.0.2:80
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 9000 -j DNAT --to-destination 172.17.0.3:9000
-A DOCKER ! -i docker0 -p udp -m udp --dport 10001 -j DNAT --to-destination 172.17.0.4:10001
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8000 -j DNAT --to-destination 172.17.0.3:8000
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8443 -j DNAT --to-destination 172.17.0.4:8443
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8080 -j DNAT --to-destination 172.17.0.4:8080
-A DOCKER ! -i docker0 -p udp -m udp --dport 3478 -j DNAT --to-destination 172.17.0.4:3478
COMMIT
# Completed on Sun Feb 26 12:27:58 2023
I tried adding a specific rule for the subnet I'm trying to route with
sudo iptables -t nat -A POSTROUTING -s 192.168.4.0/24 ! -o eth0 -j MASQUERADE
I also tried cleaning the ip tables with sudo iptables -F , but docker seems to immediately change the file again
