Re: [gentoo-user] IPTABLES syntax change?

[Michael Orlitzky]

On 12/30/12 22:21, Walter Dnes wrote:
>   OK, here is version 2.  I had "an excellent adventure" along the way.
>

I'm doing the upgrade on our servers right now, and there's another
possible gotcha: the newer iptables (requiring conntrack) requires
NETFILTER_XT_MATCH_CONNTRACK support in the kernel. This is in contrast
to the state matches which used NETFILTER_XT_MATCH_STATE.

To minimize downtime during the switch, I'm doing,

  1. Rebuild the kernel, enable conntrack and disable state.

  2. Fix my iptables-config script to use the conntrack stuff

  3. Create a dummy set of rules that allows me to SSH in (without
     state matching)

  4. Run and save those rules

  5. Reboot to new kernel

  6. SSH in and run iptables-config

  7. Save the rules


> [0:0] -A INPUT -s 192.168.123.248/29 -i eth0 -j ACCEPT
> [0:0] -A INPUT -s 169.254.0.0/16 -i eth0 -j ACCEPT
> [0:0] -A INPUT -i lo -j ACCEPT
> [0:0] -A INPUT -m conntrack --ctstate INVALID,NEW -j UNSOLICITED
> [0:0] -A INPUT -p tcp -m multiport --dports 0:1023,6000:6063 -j BAD_DPORT
> [0:0] -A INPUT -p udp -m multiport --dports 0:1023,6000:6063 -j BAD_DPORT
> [0:0] -A INPUT -s 69.63.176.0/20 -j FECESBOOK
> [0:0] -A INPUT -s 69.220.144.0/20 -j FECESBOOK
> [0:0] -A INPUT -s 69.63.176.0/20 -j FECESBOOK
> [0:0] -A INPUT -s 69.171.224.0/19 -j FECESBOOK
> [0:0] -A INPUT -s 200.58.112.0/20 -j FECESBOOK
> [0:0] -A INPUT -s 213.155.64.0/19 -j FECESBOOK
> [0:0] -A INPUT -s 10.0.0.0/8 -j PRIVATE_LOG
> [0:0] -A INPUT -s 127.0.0.0/8 -j PRIVATE_LOG
> [0:0] -A INPUT -s 172.16.0.0/12 -j PRIVATE_LOG
> [0:0] -A INPUT -s 192.168.0.0/16 -j PRIVATE_LOG
> [0:0] -A INPUT -p icmp -j ICMP_IN
> [0:0] -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

These rules will be evaluated in order. I have no evidence for this, but
I suspect you're better off accepting the ESTABLISHED,RELATED stuff
earlier in the chain so you don't slow down the packets that you want.