On 2005.10.25 13:40, Marc Peiser - marc@xxxxxxxxxxxxx wrote:
Hi,
I'm trying to setup a firewall at our data center and I think I'm missing a
few things here. I have a Class C ip range, lets call it 1.2.3.0/24. I have
a firewall running kernel 2.6.9 and iptables 1.2.11. My firewall has 2
network interfaces, on the external interface I've added an alias for each
external ip that I want to nat to internal servers:
eg. ifconfig eth0:0 1.2.3.10 netmask 255.255.255.0
(Is this the correct way to use multiple ip's?)
My servers on the inside interface are on the 192.168.0.0/24 network.
I'm able to ssh to an internal server via an external ip address.
The problem is I can't seem to connect out (via ssh, dns, www etc) from the
inside servers. There is a rule blocking these connections as it shows me in
the firewall logs:
Oct 25 18:27:22 fw1 kernel: IN=eth1 OUT=eth0 SRC=192.168.0.20 DST=4.3.2.1
LEN=60 TOS=0x00 PREC=0x00 TTL=63 ID=28642 DF PROTO=UDP SPT=32769 DPT=53
LEN=40
Oct 25 18:27:31 fw1 kernel: IN=eth1 OUT=eth0 SRC=192.168.0.20 DST=4.3.2.1
LEN=60 TOS=0x00 PREC=0x00 TTL=63 ID=18271 DF PROTO=TCP SPT=32792 DPT=22
WINDOW=5840 RES=0x00 SYN URGP=0
I've attached my firewall script, could someone please take a look at it and
give me a hand. Or if they have a similar setup, could you send me your
config. If there is a better way to do this, please let me know.
It appears there is no way to start an outbound connection.
You need a rule like this for each outbound service you allow.
$IPT -A FORWARD -i $INT_INTERFACE -o $EXT_INTERFACE -p tcp --dport 22 -m state
--state NEW -j ACCEPT
Many thanks,
Marc
