Hello Sascha
Yes, there are advantages.
I think your first router (the avm-box) has only one ethernet port.
If you decide to setup a DMZ (for your Servers) and/or a separate
Network for wireless-LAN than it's very usefull to have more then one
ethernet-port available in your router.
For example:
[Internet]
|
|
|
[small_routerbox]
|
|
|
[DMZ] --- [Linux Router] --- [Wireless LAN]
|
|
|
[LAN]
The other thing is if you want to block unknown computers with unknown
MAC-Adresses or unknown MAC-Adress/IP-Adress combinations and you add
a new host, then you have to add the new rule on every host in your
network.
For example on my router there is a chain like that:
root@gateway:~# iptables -nvL eth0_MACCHECK
Chain eth0_MACCHECK (3 references)
pkts bytes target prot opt in out source destination
2091 130K RETURN all -- * * 192.168.9.4 0.0.0.0/0 MAC aa:bb:ee:ff:gg:hh
23 1687 RETURN all -- * * 192.168.9.8 0.0.0.0/0 MAC ii:jj:kk:ll:mm:nn
[...]
0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 7 level 4 prefix `FW: eth0_MACCHECK -j DROP '
0 0 DROP all -- * * 0.0.0.0/0 0.0.0.0/0
root@gateway:~#
You can see there is "RETURN" instead of "ACCEPT" in the chain above.
And this chain (eth0_MACCHECK) is used in my eth0_INPUT and
eth0_FORWARD chain.
root@gateway:~# iptables -nvL eth0_INPUT
Chain eth0_INPUT (1 references)
pkts bytes target prot opt in out source destination
228 18332 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
1 60 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
7 3784 ACCEPT udp -- * * 0.0.0.0/0 0.0.0.0/0 udp dpt:67
66 5016 eth0_MACCHECK all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmp type 8
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:113
0 0 ACCEPT udp -- * * 0.0.0.0/0 0.0.0.0/0 udp dpt:53
66 5016 ACCEPT udp -- * * 0.0.0.0/0 0.0.0.0/0 udp dpt:123
0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 7 level 4 prefix `FW: eth0_INPUT -j DROP '
0 0 DROP all -- * * 0.0.0.0/0 0.0.0.0/0
root@gateway:~#
You can see there is "eth0_MACCHECK" instead of "ACCEPT".
and last but not least my INPUT chain:
root@gateway:~# iptables -nvL INPUT
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
54 5958 eth2_INPUT all -- eth2 * 0.0.0.0/0 0.0.0.0/0
249 24910 eth1_INPUT all -- eth1 * 0.0.0.0/0 0.0.0.0/0
404 34536 eth0_INPUT all -- eth0 * 0.0.0.0/0 0.0.0.0/0
56 5698 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 LOG flags 7 level 4 prefix `FW: INPUT -j DROP '
root@gateway:~#
Here there is "eth0_INPUT" instead of "ACCEPT".
My forward-chains look similar to my input-chains with a few
differences and the eth0_MACCHECK chain is used in both INPUT and FORWARD.
You can use a brute-force-check chain too like that:
Chain brute_force_check (2 references)
pkts bytes target prot opt in out source destination
85619 13M all -- * * 0.0.0.0/0 0.0.0.0/0
state NEW recent: SET name: DEFAULT side: source
52330 7461K LOG all -- * * 0.0.0.0/0 0.0.0.0/0
state NEW recent: UPDATE seconds: 60 hit_count: 4 name: DEFAULT side: so
urce LOG flags 7 level 4 prefix `FW: brute_force_check '
52330 7461K DROP all -- * * 0.0.0.0/0 0.0.0.0/0
state NEW recent: UPDATE seconds: 60 hit_count: 4 name: DEFAULT side: so
urce
38676 7956K RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
I know there could be more security by dropping new packets without
the SYN-Flag set, and so on.
Perhaps you and or other people on the list can give me/us some hints
about that.
best regards
Mario Koppensteiner
On Sat, Mar 03, 2007 at 01:36:19AM -0800, sascha s wrote:
> hey list,
>
> im using two router to set up my internet connection and protect my home network. the first is just a little router from avm and the second is a pIII with linux and iptables. since the second box had some hardware trouble im considering to use just the first router and add the iptables rules to workstations (also linux). i dont use any special feature like vpn or something like that. are there any big advantages of having a dedicated linux router?
>
>
> thanks for help and best regards
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