### To see if the kernel modules are loaded:
```
lsmod | grep ip_tables
To see the effective rules:
```
```
iptables -L
```
or, if you want to see the NAT rules:
```
iptables -t nat -L
```
In Debian there are a number of firewall packages that can set up the iptables rules for you. (I have not tried any of them, I usually roll out my own when I need it).
```
apt-cache search firewall | grep firewall | less
```