I'm trying to set up Dachstein to sit between our LAN and our ISP. I can
ping the loopback and everything in the LAN from the firewall box, but I
cannot ping the external gateway nor anything else outside the LAN. The
LEAF ping FAQ suggest that my firewalling rules need to be tweaked, but
being new to firewalling and to Linux I need guidance. The details:
Running Dachstein 1.0.2 floppy image. uname -a reports:
Linux firewall 2.2.19-3-LEAF #1 Sat Dec 1 12:15:05 CST 2001 i386 unknown
Our LAN uses 192.168.0.x addresses and Dachstein assumes internal
addresses of 192.168.1.x, so I have attempted to make all necessary
changes. I have also attempted to assign the firewall a static internal
address of 192.168.0.3, which is within the range of IP addresses
excluded from distribution on our LAN's DHCP server.
The final topology will be:
ISP - firewall - LAN hub - server and workstations
Right now for configuration and testing purposes, I have:
ISP - LAN hub - server, workstations, and firewall (firewall's two NICs
are for now both plugged into the hub)
Yes, I know, that means our LAN is wide open. So hack us now while you
have the chance.
For what it's worth, our ISP is the Internet caf� next door. I've
connected their hub to our hub.
ip addr show reports:
1: lo: <LOOPBACK,UP> mtu 3924 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 brd 127.255.255.255 scope global lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:e0:7d:d5:7e:8a brd ff:ff:ff:ff:ff:ff
inet 65.167.30.126/27 brd 65.167.30.127 scope global eth0
3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:e0:7d:ac:0c:0f brd ff:ff:ff:ff:ff:ff
inet 192.168.0.3/24 brd 192.168.0.255 scope global eth1
ip route show reports:
65.167.30.96/27 dev eth0 proto kernel scope link src 65.167.30.126
192.168.0.0/24 dev eth1 proto kernel scope link src 192.168.0.3
ping 65.167.30.174 from the firewall reports:
ping: sendto: Network is unreachable
Just to show that this is a valid address, pinging 65.167.30.174 from a
workstation does work if it is configured to the external net, and the
Internet connection works fine.
ipchains -nvL reports:
Chain input (policy DENY: 0 packets, 0 bytes):
pkts bytes target prot opt tosa tosx ifname mark
outsize source destination ports
0 0 DENY icmp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 5 -> *
0 0 DENY icmp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 13 -> *
0 0 DENY icmp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 14 -> *
26 9020 DENY all ----l- 0xFF 0x00 eth0
0.0.0.0 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
255.255.255.255 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
127.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
224.0.0.0/4 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
10.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
172.16.0.0/12 0.0.0.0/0 n/a
2648 581K DENY all ----l- 0xFF 0x00 eth0
192.168.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
0.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
128.0.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
191.255.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
192.0.0.0/24 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
223.255.255.0/24 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
240.0.0.0/4 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
192.168.0.0/24 0.0.0.0/0 n/a
302 30694 DENY all ----l- 0xFF 0x00 eth0
65.167.30.126 0.0.0.0/0 n/a
0 0 REJECT all ----l- 0xFF 0x00 eth0
0.0.0.0/0 127.0.0.0/8 n/a
0 0 REJECT all ----l- 0xFF 0x00 eth0
0.0.0.0/0 192.168.0.0/24 n/a
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 137
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 135
1240 104K REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 137
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 135
12 576 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 138:139
416 91743 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 138
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 137:138 -> *
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 135 -> *
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 137:139 -> *
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 135 -> *
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 113
39 1712 ACCEPT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 1024:65535
0 0 REJECT udp ----l- 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 161:162
0 0 ACCEPT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 53
0 0 ACCEPT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 68
0 0 DENY udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 67
23 3453 ACCEPT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 1024:65535
21 1708 ACCEPT icmp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> *
0 0 ACCEPT ospf ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 n/a
6 300 DENY all ----l- 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 n/a
0 0 REJECT udp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 * -> 161:162
0 0 REJECT udp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 161:162 -> *
4633 813K ACCEPT all ------ 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 n/a
Chain forward (policy DENY: 0 packets, 0 bytes):
pkts bytes target prot opt tosa tosx ifname mark
outsize source destination ports
0 0 DENY icmp ----l- 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 5 -> *
0 0 MASQ all ------ 0xFF 0x00 eth0
192.168.0.0/24 0.0.0.0/0 n/a
0 0 DENY all ------ 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 n/a
Chain output (policy DENY: 0 packets, 0 bytes):
pkts bytes target prot opt tosa tosx ifname mark
outsize source destination ports
66 5448 fairq all ------ 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
0.0.0.0 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
255.255.255.255 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
127.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
224.0.0.0/4 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
10.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
172.16.0.0/12 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
192.168.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
0.0.0.0/8 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
128.0.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
191.255.0.0/16 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
192.0.0.0/24 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
223.255.255.0/24 0.0.0.0/0 n/a
0 0 DENY all ----l- 0xFF 0x00 eth0
240.0.0.0/4 0.0.0.0/0 n/a
0 0 DENY all ------ 0xFF 0x00 eth0
192.168.0.0/24 0.0.0.0/0 n/a
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 137
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 135
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 137
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 135
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 138:139
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 * -> 138
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 137:138 -> *
0 0 REJECT udp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 135 -> *
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 137:139 -> *
0 0 REJECT tcp ------ 0xFF 0x00 eth0
0.0.0.0/0 0.0.0.0/0 135 -> *
66 5448 ACCEPT all ------ 0xFF 0x00 *
0.0.0.0/0 0.0.0.0/0 n/a
Chain fairq (1 references):
pkts bytes target prot opt tosa tosx ifname mark
outsize source destination ports
0 0 RETURN ospf ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 n/a
0 0 RETURN ospf ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 n/a
0 0 RETURN udp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 * -> 520
0 0 RETURN udp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 520 -> *
0 0 RETURN tcp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 * -> 179
0 0 RETURN tcp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 179 -> *
0 0 RETURN tcp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 * -> 53
0 0 RETURN tcp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 53 -> *
0 0 RETURN udp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 * -> 53
0 0 RETURN udp ------ 0xFF 0x00 * 0x1
0.0.0.0/0 0.0.0.0/0 53 -> *
0 0 RETURN tcp ------ 0xFF 0x00 * 0x2
0.0.0.0/0 0.0.0.0/0 * -> 23
0 0 RETURN tcp ------ 0xFF 0x00 * 0x2
0.0.0.0/0 0.0.0.0/0 23 -> *
0 0 RETURN tcp ------ 0xFF 0x00 * 0x2
0.0.0.0/0 0.0.0.0/0 * -> 22
0 0 RETURN tcp ------ 0xFF 0x00 * 0x2
0.0.0.0/0 0.0.0.0/0 22 -> *
/var/log/messages is nearly 300K of deny messages. Here's a snip:
Sep 17 13:09:56 firewall kernel: Packet log: input DENY eth0 PROTO=17
192.168.0.1:138 192.168.0.255:138 L=210 S=0x00 I=17289 F=0x0000 T=128 (#10)
Sep 17 13:09:57 firewall kernel: Packet log: input DENY eth0 PROTO=17
192.168.0.35:138 192.168.0.255:138 L=211 S=0x00 I=2907 F=0x0000 T=128 (#10)
192.168.0.1 is the server on our LAN. 192.168.0.35 is a workstation on
our LAN.
Observations or suggestions, anyone?
--
Warren Post, Voluntario Naciones Unidas
Departamento de Inform�tica
Municipalidad de Santa Rosa de Cop�n, Honduras
http://www.santarosahistorica.org/
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