I am using Red Hat 8 (2.4.18-14) with Iptable
(V1.2.6.a) , the layout of my net is:
Host A ---------- Firewall ------
Host B
(Outside)
(My_WS)
Net A: 172.19.100.0 - 172.19.100.31
Netmask : 255.255.255.224
IP A: 172.19.100.28
GW: 172.19.100.30
Net B: 172.19.100.32 - 172.19.100.63
Netmask: 255.255.255.224
IP B: 172.19.100.50
GW: 172.19.100.33
And for the Firewall:
Eth0: 172.19.100.30
Eth1: 172.19.100.33
Both with netmask 255.255.255.224
The rules for the Firewall are:
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out
source destination
1 0 0 ACCEPT all -- lo *
0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out
source destination
1 0 0 ACCEPT all -- * lo
0.0.0.0/0 0.0.0.0/0
Chain FORWARD (policy DROP 0 packets, 0 bytes)
num pkts bytes target prot opt in out
source destination
1 0 0 ACCEPT tcp -- eth0 eth1
0.0.0.0/0 172.19.100.50 tcp dpt:80
2 0 0 ACCEPT all -- eth0 eth1
0.0.0.0/0 0.0.0.0/0 state
RELATED,ESTABLISHED
3 0 0 ACCEPT all -- eth1 eth0
0.0.0.0/0 0.0.0.0/0
The forward is enable in the FW (echo "1" >
/proc/sys/net/ipv4/ip_forward)and the routing table
is:
Kernel IP routing table
Destination Gateway Genmask Flags
Metric Ref Use Iface
172.19.100.32 * 255.255.255.224 U
0 0 0 eth1
172.19.100.0 * 255.255.255.224 U
0 0 0 eth0
127.0.0.0 * 255.0.0.0 U
0 0 0 lo
default 172.19.100.1 0.0.0.0 UG
0 0 0 eth0
I want that everything from Net B can go out, but from
Net A only to host B is allow.
Ok, where we go, if I tray to the webserver on host B
from host A everything is OK, then I make a ping form
host B to host A and also work. But if I down the
interface on host B and then bring it up again, when I
ping host A from host B doesn't work. I tray with
another hosts on LAN B (say 172.19.100.54) and it's
the same, all the packets are lost.
The only way I found to work is first make a ping to
the FW from host B and then retry
to host A.
Thanks for your help.
Sorry, about my english.
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