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Why don't these ebtables rules work right?

Link to this post 18 May 09

This is on a bridging firewall
eth0 it das internaught
eth1 is the trusted network

It is supposed to allow port 22 in from the internet (works)
and allow a specific box to connect to http and https server,
and allow nothing else for now out or in. It also is supposed to makesure no ip spoofing of the specific box happens.

The port 22 in works.
The http and https out doesn't


###The invisible bridge way:

/usr/sbin/brctl addbr br0
/usr/sbin/brctl addif br0 eth0
/usr/sbin/brctl addif br0 eth1
/sbin/ip link set br0 up
/sbin/ip link set eth0 up # don't ask me why
/sbin/ip link set eth1 up # don't ask me why
#/sbin/ip addr add 192.168.0.6 brd + dev br0
#/sbin/route add default gw 192.168.0.1 dev br0 ##Only needed if eth2 hasn't allready set default gateway

# ebtables...
# example rule: block all ICMP
ebtables -F FORWARD
ebtables -A FORWARD -p ip --ip-proto icmp -j DROP ## block all ICMP
#ebtables -A FORWARD -i eth0 -j DROP

##Here We allow SSH to pass through to the ssh server
#Incoming Connection From Internet #ebtables -i eth0 -o eth1 -p ip --ip-proto tcp --ip-destination-port 22 --ip-destination ip-of-the-ssh-server -j ACCEPT
#Reply by the server To Internet #ebtables -i eth1 -o eth0 -p ip --ip-proto tcp --ip-source-port 22 --ip-source ip-of-the-ssh-server -j ACCEPT
ebtables -A FORWARD -i eth0 -o eth1 -p ip --ip-proto tcp --ip-destination-port 22 --ip-destination 192.168.0.22 -j ACCEPT
ebtables -A FORWARD -i eth1 -o eth0 -p ip --ip-proto tcp --ip-source-port 22 --ip-source 192.168.0.22 -j ACCEPT

##Allow squid server to access HTTP and HTTPS servers on standard ports.
#Incoming Packets From HTTP Server on Internet# ebtables -i eth0 -o eth1 -p ip --ip-destination squidserver -d macaddress-of-squidserver --ip-proto tcp --ip-source-port 80 -j ACCEPT
#Outgoing Packets From Clients on School Network# ebtables -i eth1 -o eth0 -p ip --ip-source squidserver -s macaddress-of-squidserver --ip-proto tcp --ip-destination-port 80 -j ACCEPT
#Incoming Packets From HTTP Server on Internet# ebtables -i eth0 -o eth1 -p ip --ip-destination squidserver -d macaddress-of-squidserver --ip-proto tcp --ip-source-port 443 -j ACCEPT
#Outgoing Packets From Clients on School Network# ebtables -i eth1 -o eth0 -p ip --ip-source squidserver -s macaddress-of-squidserver --ip-proto tcp --ip-destination-port 443 -j ACCEPT
##Anti-spoofing rule (Only matches the IP address of squidserver, not MAC address)
ebtables -A FORWARD -i eth0 -o eth1 -p ip --ip-destination 192.168.0.22 -d 00:08:0D:54:13:C9 --ip-proto tcp --ip-source-port 80 -j ACCEPT
ebtables -A FORWARD -i eth1 -o eth0 -p ip --ip-source 192.168.0.22 -s 00:08:0D:54:13:C9 --ip-proto tcp --ip-destination-port 80 -j ACCEPT
ebtables -A FORWARD -i eth0 -o eth1 -p ip --ip-destination 192.168.0.22 -d 00:08:0D:54:13:C9 --ip-proto tcp --ip-source-port 443 -j ACCEPT
ebtables -A FORWARD -i eth1 -o eth0 -p ip --ip-source 192.168.0.22 -s 00:08:0D:54:13:C9 --ip-proto tcp --ip-destination-port 443 -j ACCEPT
##Anti-spoofing rule (Only matches the IP address of squidserver, not MAC address)
ebtables -A FORWARD -i eth0 -p ip --ip-source 192.168.0.22 -j DROP

ebtables -A FORWARD -i eth0 -j DROP

Link to this post 18 May 09

I am not an iptables expert and I am not sure about how you handle the ports 80 and 443 with those forward rules but how about simply doing something along the lines of:


iptables -A INPUT -p tcp -s xxx.xxx.xxx.xxx -d yyy.yyy.yyy.yyy -m tcp --syn --dport 80 -j ACCEPT

Link to this post 18 May 09

This is ebtables (ethernet bridge). It cannot use iptables and can't really screw with the protocal stuff IIRC (other than notice what proto is being used).

Link to this post 18 May 09

Bridge chain: FORWARD, entries: 8, policy: DROP
-p IPv4 --ip-proto icmp -j DROP
-p IPv4 -i eth0 -o eth1 --ip-dst 192.168.0.22 --ip-proto tcp --ip-dport 22 -j ACCEPT
-p IPv4 -i eth1 -o eth0 --ip-src 192.168.0.22 --ip-proto tcp --ip-sport 22 -j ACCEPT
-p IPv4 -d 0:8:d:54:13:c9 -i eth0 -o eth1 --ip-dst 192.168.0.22 --ip-proto tcp --ip-sport 80 -j ACCEPT
-p IPv4 -s 0:8:d:54:13:c9 -i eth1 -o eth0 --ip-src 192.168.0.22 --ip-proto tcp --ip-dport 80 -j ACCEPT
-p IPv4 -d 0:8:d:54:13:c9 -i eth0 -o eth1 --ip-dst 192.168.0.22 --ip-proto tcp --ip-sport 443 -j ACCEPT
-p IPv4 -s 0:8:d:54:13:c9 -i eth1 -o eth0 --ip-src 192.168.0.22 --ip-proto tcp --ip-dport 443 -j ACCEPT
-p IPv4 -i eth0 --ip-src 192.168.0.22 -j DROP

Why doesn't this work?

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