iainr

I set both network cards for DHCP. Then I typed "service network restart"

Here is my address according to ifconfig:

eth0: 192.168.1.103
eth1: 192.168.1.102

These are DHCP addresses, because the DHCP server gives out addresses in the range 192.168.1.100 to 192.168.1.199

I ping each of those addresses from Windows ME:

If I ping the router from the server:

Same if I ping the windows ME computer.

DANG, how am I getting an IP address then!!!

Here are the contents of those files I see other people asking for:

cat /etc/sysconfig/network
NETWORKING=yes
FORWARD_IPV4=yes
HOSTNAME=localhost.localdomain

DOMAINNAME=localdomain

# Gateway configuration
GATEWAYDEV=eth1
GATEWAY=

cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp

cat /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
ONBOOT=yes
BOOTPROTO=dhcp

Have you tried rebooting the box? That will reload the kernel and, since everything looks OK but still doesn't work, that is definitely something worth trying at this stage.

Hi iainr,

The server is always switched off when I'm not using it, because it's very noisy and I work in a cubicle. So it's been rebooted several times.

Could ICMP be disabled somehow? How can I test to see if other protocols are working? I can get an IP after all...

Yes ICMP could be turned off. There is a file in /proc/net I think you do a echo "1">/proc/net/somefile but I cant find it on my system right now. I'll look some more.

cat /proc/sys/net/ipv4/icmp_echo_ignore_all
0

If you get a 1 then you will ignore all icmp pings. So you should do this:
echo "0" >/proc/sys/net/ipv4/icmp_echo_ignore_all

/bin/bash

I appreciate all your help! please don't give up

I already modified this file (previous page)... it gave me the ability to ping 127.0.0.1 and my own IP. Before that i couldn't even ping myself, but now I can.

Still can't ping anyone else though. What puzzles me is how can I get an IP address from the router but not be able to ping it? And I can not access the Linux server from Windows using https:?

Could it be related to iptables? it could be rejecting all outgoing and incoming traffic? what can I type to find out?

I'd suggest job #1 is to disable the NIC you intend to use for the ADSL modem, and get the Linux box working as an ordinary network client. Something like "ifconfig eth1 down". That should also kill any forwarding for now. To eliminate all possible confusion you could go as far as removing the card from the server.

Only after the Linix machine can play ball with the XP boxes, without sulking, would it be safe to use it as a firewall/router.

The job it will need to do is to convince all the XP machines that IT is an ADSL modem/router. That means it must provide the same services: DHCP and routing/NAT.

It is difficult tracking down problems on a live network, so always try to isolate and identify each problem. Make things a simple as possible. I see the second NIC as a continual source of uncertainty, so I'd suggest removing it until it's needed.

Sorry for not paying attention. I have read this whole thread but I have read several more just like it and I sometimes forget the specifics of what has and hasn't been done.

You could try tcpdump. Here is what it might look like if you sent one ping out to your router on eth0:

# tcpdump -i eth0
tcpdump: listening on eth0
20:11:27.276087 arp who-has jimmyneutron tell spongebob
20:11:27.276509 arp reply jimmyneutron is-at 0:65:5:df:f4:5e
20:11:27.276533 spongebob > jimmyneutron: icmp: echo request (DF)
20:11:27.277193 jimmyneutron > spongebob: icmp: echo reply



Is this still how the routing table looks because if so then your default route is wrong.
You have eth1 -> 192.168.2.1 = default gateway and I think it should be eth0. You could try changing GATEWAYDEV=eth1 to eth0 in /etc/sysconfig/network .

OK here's what I did:

- netconfig -d eth1 ip=192.168.1.99 (was 192.168.1.2)
- service network restart
- ifconfig eth0 down
- ifconfig:
eth1: Link encap:Ethernet HWaddr: 00:09:6B:63:15:4F
----- inet addr: 192.168.1.66 Bcast: 192.168.1.255 Mask: 255.255.255.0
----- UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
----- RX packets:1 errors:0 dropped:0 overruns:0 frame:0
----- TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
----- collisions:0 txqueuelen:100
----- RX bytes:64 (64.0 b) TX bytes:64 (64.0 b)
----- Interrupt:25 Memory:fbfe0000-fbff0000

lo: Link encap: Local loopback
----- inet addr:127.0.0.1 Mask:255.255.255.0
(etc)

- ping -I eth1 192.168.1.1
PING 192.168.1.1 (192.168.1.1) from 192.168.1.66 eth1: 56(84) bytes of data.
(pause) CTRL+C
--- 192.168.1.1 ping statistics ---
8 packets transmitted, 0 packets received, 100% packet loss

- tcpdump -i eth1
tcpdump: listening on eth1
10:50:53.813121 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:53.818516 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:54.013607 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:55.209587 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:55.220135 arp who-has 192.168.1.2 (1:77:0:35:4:15) tell 192.168.1.1
10:50:55.308127 arp who-has 192.168.1.2 (24:fa:4:e0:0:50) tell 192.168.1.1
10:50:56.536855 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:56.550740 arp who-has 192.168.1.2 (1:71:0:50:4:e0) tell 192.168.1.1
10:50:57.748643 arp who-has 192.168.1.2 (b1:7c:4:e4:0:50) tell 192.168.1.1
(later)
>>> NBT UDP PACKET (137): QUERY; POSITIVE; RESPONSE; UNICAST
11:04:47.937319 192.168.1.122.netbios-dgm > 192.168.1.209.netbios.dgm:
>>> NBT UDP PACKET (138) Res=0x1002 ID-0x99 IP=192 (0xc0).168 (0xa8).1 (0x1).122 (0x7a) Port=138 (0x8a) Length=171 (0xab) Res2=0x0
SOURCE NAME=IBMFB1L0DH Name Type=0x20 (Server)
DestName=
WARNING: Short packet. Try increasing the snap length
etc.... CTRL+C

17 packets received by filter
0 packets dropped by kernel

- route -n
Kernel IP routing table
Destination -- Gateway -- Genmask ------- Flags Metric Ref Iface
192.168.1.0 - 0.0.0.0 ---- 255.255.255.0 - - U - - 0 - - - 0 - eth1
127.0.0.1 ---- 0.0.0.0 ---- 255.0.0.0 - - - - - -U - - -0 - - - 0 - -lo
0.0.0.0 ----- 192.168.1.1 - 0.0.0.0 - - - - - - -UG - -0 - - - 0 - eth1

(note, the routing table changes every time I change my IP addresses or what not. But I've never been able to get a gateway entry for eth0)

Additionally

(found this command in another thread) nmap -sP 192.168.1.0/24
says "Host (192.168.1.XXX) appears to be up"

Nmap run completed -- 256 IP addresses (20 hosts up) scanned in 6 seconds

AND, I have both shorewall and what seems to be a huge iptables file. Could these be interfereing with my connectivity somehow? How can I disable/test this?

Interesting

I tried running a tcpdump, and then while it was listening, to ping the Linux box from Windows ME.

Here's the result:

11:45:44.757229 arp who-has 192.168.1.66 tell 192.168.1.122
11:45:44.757247 arp reply 192.168.1.66 is-at 0:9:6b:63:15:4f
11:45:44.757496 192.168.1.122 > 192.168.1.66: icmp: echo request
11:45:44.757744 192.168.1.66 > 192.168.1.122: icmp: 192.168.1.66 protocol 1 port 16220 unreachable (DF) [tos 0xc0]
11:45:45.762476 192.168.1.122 > 192.168.1.66: icmp: echo request
11:45:45.762525 192.168.1.66 > 192.168.1.122: icmp: 192.168.1.66 protocol 1 port 15964 unreachable (DF) [tos 0xc0]
11:45:46.757343 192.168.1.122 > 192.168.1.66: icmp: echo request
11:45:46.757392 192.168.1.66 > 192.168.1.122: icmp: 192.168.1.66 protocol 1 port 15708 unreachable (DF) [tos 0xc0]
11:45:47.762253 192.168.1.122 > 192.168.1.66: icmp: echo request
11:45:47.762297 192.168.1.66 > 192.168.1.122: icmp: 192.168.1.66 protocol 1 port 15452 unreachable (DF) [tos 0xc0]
11:45:48.867112 192.168.1.122.1580 > 216.239.57.104.http: R 1945308827:1945308827(0) win 0 (DF)
11:45:49.755858 arp who-has 192.168.1.122 tell 192.168.1.66
11:45:49.756143 arp reply 192.168.1.122 is-at 0:50:ba:45:2c:5b

21 packets received by filter
0 packets dropped by kernel

OK well i solved the mystery.

I had to disable shorewall:

[root@localhost ]# shorewall stop

enable icmp

[root@localhost ]# echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

and delete, remove executable, and flush IP tables (after backing up onto floppy of course

[root@localhost ]# cd /etc/rc.d/init.d
[root@localhost ]# rm iptables
[root@localhost ]# chmod -x iptables // yes it makes another one
[root@localhost ]# iptables -F (get rid of all the default rulse
[root@localhost ]# iptables -P INPUT ACCEPT
[root@localhost ]# iptables -P OUTPUT ACCEPT
[root@localhost ]# iptables -P FORWARD ACCEPT

finally!!!

[root@localhost ]# ping 192.168.1.1
PING 192.168.1.1 from 192.168.1.66 : 56(84) bytes of data
64 bytes from 192.168.1.1: icmp_seq=0 ttl=128 time=726 usec
64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=403 usec
64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=402 usec

--- 192.168.1.1 ping statistics
3 packets transmitted, 3 packets received, 0% packet loss

*YAY*

Of course, i now have no firewall and no protection. But at least i can function better. Yeesh.

[root@localhost ]# cd /etc/rc.d/init.d
[root@localhost ]# rm iptables
[root@localhost ]# chmod -x iptables // yes it makes another one
[root@localhost ]# iptables -F (get rid of all the default rulse
[root@localhost ]# iptables -P INPUT ACCEPT
[root@localhost ]# iptables -P OUTPUT ACCEPT
[root@localhost ]# iptables -P FORWARD ACCEPT

You could replace all that with this:
service iptables stop
/sbin/chkconfig --level 12345 iptables off