| 1 |
Marco wrote: |
| 2 |
> Hi all, |
| 3 |
> |
| 4 |
> I set up my first firewall on my notebook (not running any services |
| 5 |
> reachable from outside) using iptables. Since I am new to the topic, |
| 6 |
> could you please verify if the output of 'iptables -L -v' is |
| 7 |
> considered to be a safe firewall? Thanks! |
| 8 |
> |
| 9 |
> Chain INPUT (policy DROP 0 packets, 0 bytes) |
| 10 |
> pkts bytes target prot opt in out source |
| 11 |
> destination |
| 12 |
> 0 0 ACCEPT all -- lo any anywhere |
| 13 |
> anywhere |
| 14 |
> 0 0 ACCEPT all -- eth0 any anywhere |
| 15 |
> anywhere state RELATED,ESTABLISHED |
| 16 |
> 0 0 REJECT tcp -- eth0 any anywhere |
| 17 |
> anywhere reject-with tcp-reset |
| 18 |
> 0 0 REJECT udp -- eth0 any anywhere |
| 19 |
> anywhere reject-with icmp-port-unreachable |
| 20 |
> 0 0 DROP udp -- eth0 any anywhere |
| 21 |
> anywhere udp spt:bootps |
| 22 |
> 0 0 LOG all -- eth0 any anywhere |
| 23 |
> anywhere LOG level warning prefix `INPUT ' |
| 24 |
> 1 79 ACCEPT all -- wlan0 any anywhere |
| 25 |
> anywhere state RELATED,ESTABLISHED |
| 26 |
> 0 0 REJECT tcp -- wlan0 any anywhere |
| 27 |
> anywhere reject-with tcp-reset |
| 28 |
> 0 0 REJECT udp -- wlan0 any anywhere |
| 29 |
> anywhere reject-with icmp-port-unreachable |
| 30 |
> 0 0 DROP udp -- wlan0 any anywhere |
| 31 |
> anywhere udp spt:bootps |
| 32 |
> 0 0 LOG all -- wlan0 any anywhere |
| 33 |
> anywhere LOG level warning prefix `INPUT ' |
| 34 |
> |
| 35 |
> Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) |
| 36 |
> pkts bytes target prot opt in out source |
| 37 |
> destination |
| 38 |
> 0 0 LOG all -- any any anywhere |
| 39 |
> anywhere LOG level warning prefix `FORWARD ' |
| 40 |
> 0 0 LOG all -- any any anywhere |
| 41 |
> anywhere LOG level warning prefix `FORWARD ' |
| 42 |
> |
| 43 |
> Chain OUTPUT (policy ACCEPT 5 packets, 1691 bytes) |
| 44 |
> pkts bytes target prot opt in out source |
| 45 |
> destination |
| 46 |
> 0 0 ACCEPT all -- any lo anywhere |
| 47 |
> anywhere |
| 48 |
> 0 0 LOG all -- any eth0 anywhere |
| 49 |
> anywhere LOG level warning prefix `OUTPUT ' |
| 50 |
> 1 52 LOG all -- any wlan0 anywhere |
| 51 |
> anywhere LOG level warning prefix `OUTPUT ' |
| 52 |
> |
| 53 |
> |
| 54 |
It all depends on what you're trying to do. My internet facing boxes |
| 55 |
have a default OUTPUT policy of DROP and I only allow certain traffic |
| 56 |
off of the box (helps protect me from unauthorized services). Also, |
| 57 |
you're dropping bootps (same ports as dhcp) on udp so I don't think you |
| 58 |
can get a dhcp address like that. If you're running any services you |
| 59 |
won't be able to talk to them (ssh). Turn off forwarding in the kernel |
| 60 |
config (via /etc/sysctl.conf) as well. |
| 61 |
|
| 62 |
It also took me a few runs to figure out the firewall config (due to the |
| 63 |
rules and formatting). The last two output rules can be combined into |
| 64 |
one. Have 1 log line at the bottom of your tables and that will take |
| 65 |
care of that. Clean and short configs will help immensely when things |
| 66 |
don't work. |
Archives