network not recognizing new node.

bulliver · 10-22-2004, 03:10 PM

Hello All. Just went out and got a laptop today, and I am trying to install gentoo on it but I cannot get the networking to work. First of all, here is a crude ascii map of the network:

Code:

                                         | to internet
 Server:                              |
                              eth0     |  public IP
            ----------------------------------------------------
eth1      |  192.168.0.1                                      eth2  |  192.168.0.3
            |                                                                |
            |                                                                |
workstation 192.168.0.2                                    laptop 192.168.0.4

Before was only the server and workstation, which has worked fine. Today I added the laptop and configured it to be 192.168.0.4 and use 192.168.0.3 as the default gw. All the interfaces are physically installed and up and running, but I cannot ping from server to laptop or vice versa.

Servers ifconfig is:

Code:

eth0      Link encap:Ethernet  HWaddr 00:40:F4:5D:76:10
          inet addr:[x.x.x.x edited]  Bcast:255.255.255.255  Mask:255.255.252.0
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:622933 errors:0 dropped:0 overruns:0 frame:0
          TX packets:594974 errors:0 dropped:0 overruns:0 carrier:0
          collisions:4029 txqueuelen:1000
          RX bytes:431501388 (411.5 Mb)  TX bytes:222592242 (212.2 Mb)
          Interrupt:9 Base address:0xb00

eth1      Link encap:Ethernet  HWaddr 00:40:F4:39:9D:90
          inet addr:192.168.0.1  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:427589 errors:0 dropped:0 overruns:0 frame:0
          TX packets:476408 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:58318191 (55.6 Mb)  TX bytes:426609509 (406.8 Mb)
          Interrupt:5 Base address:0x2a00

eth2      Link encap:Ethernet  HWaddr 00:50:BF:A2:62:3F
          inet addr:192.168.0.3  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:60 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5348 (5.2 Kb)  TX bytes:336 (336.0 b)
          Interrupt:11 Base address:0xf800

Servers route is:

Code:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     *               255.255.255.0   U     0      0        0 eth1
192.168.0.0     *               255.255.255.0   U     0      0        0 eth2
x.x.x.0             *               255.255.252.0   U     0      0        0 eth0
loopback        localhost       255.0.0.0       UG    0      0        0 lo
default         x.x.x.x              0.0.0.0         UG    0      0        0 eth0

Ifconfig of laptop is:

Code:

eth0      Link encap:Ethernet  HWaddr 00:0F:B0:01:EF:AD
          inet addr:192.168.0.4  Bcast:255.255.255.255  Mask:255.255.252.0
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:64 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:480 (480.0 b)  TX bytes:7708 (7.5 Kb)
          Interrupt:11 Base address:0xa000

route of laptop is:

Code:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.0.0     *               255.255.255.0   U     0      0        0 eth0
loopback        localhost       255.0.0.0       UG    0      0        0 lo
default         192.168.0.3   0.0.0.0             UG    0      0        0 eth0

The server runs a NAT firewall for the workstation, so I basically doubled the rules for the laptop. I am not sure if this is the correct way to do this though. The new firewall script is:

Code:

EXTIF="eth0"
INTIF="eth1"
NBIF="eth2"

EXTIP="x.x.x.x"
INTNET="192.168.0.0/24"
INTIP="192.168.0.1"
NBIFIP="192.168.0.3"
UNIVERSE="0.0.0.0/0"
NBIP="192.168.0.4"

$IPTABLES -P INPUT DROP
$IPTABLES -F INPUT
$IPTABLES -P OUTPUT DROP
$IPTABLES -F OUTPUT
$IPTABLES -P FORWARD DROP
$IPTABLES -F FORWARD
$IPTABLES -F -t nat

$IPTABLES -X
$IPTABLES -Z

# INPUT chain
$IPTABLES -A INPUT -i eth1 -s 192.168.0.2 -d $UNIVERSE -j ACCEPT
$IPTABLES -A INPUT -i eth2 -s 192.168.0.4 -d $UNIVERSE -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -s $INTNET -d $UNIVERSE -j DROP
$IPTABLES -A INPUT -i $EXTIF -s $UNIVERSE -d $EXTIP -m state --state \
          ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A INPUT -s $UNIVERSE -d $UNIVERSE -j DROP

# OUTPUT chain
$IPTABLES -A OUTPUT -o lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT
$IPTABLES -A OUTPUT -o $INTIF -s $EXTIP -d $INTNET -j ACCEPT
$IPTABLES -A OUTPUT -o $INTIF -s $INTIP -d $INTNET -j ACCEPT
$IPTABLES -A OUTPUT -o $NBIF -s $EXTIP -d $NBIP -j ACCEPT
$IPTABLES -A OUTPUT -o $NBIF -s $NBIFIP -d $NBIP -j ACCEPT
$IPTABLES -A OUTPUT -o $EXTIF -s $UNIVERSE -d $INTNET -j DROP
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -d $UNIVERSE -j ACCEPT
$IPTABLES -A OUTPUT -s $UNIVERSE -d $UNIVERSE -j DROP

# FORWARD chain
$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -m state --state \
       ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT
$IPTABLES -A FORWARD -i $EXTIF -o $NBIF -m state --state \
        ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $NBIF -o $EXTIF -j ACCEPT
$IPTABLES -A FORWARD -j DROP

# NAT table
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j SNAT --to $EXTIP

Does someone know what I am missing, or have any troubleshooting tips? When I plug the laptop in place of the workstation it can connect to the net fine so I think the problem is with the NAT iptable rules.

Peacedog · 10-22-2004, 03:33 PM

This doesn't look correct to me anyway.

inet addr:192.168.0.4
Bcast:255.255.255.255
Mask:255.255.252.0

The broadcast and net mask look off. I might be wrong, but shouldn't the net mask be

Mask:255.255.255.0

good luck.

bulliver · 10-22-2004, 03:39 PM

That's a typo, sorry. I cut and paste the output of ifconfig on the server's eth0 and changed the values to that of the laptop, but forgot those ones. The *real* ifconfig of the laptop is:

Code:

eth0      Link encap:Ethernet  HWaddr 00:0F:B0:01:EF:AD
          inet addr:192.168.0.4  Bcast:192.168.0.255 Mask:255.255.255.0
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:64 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:480 (480.0 b)  TX bytes:7708 (7.5 Kb)
          Interrupt:11 Base address:0xa000

Peacedog · 10-22-2004, 03:44 PM

Well that looks good, you say you can plug the laptop in place of the workstation, and the connection is fine. If that's the case does the laptop retain it's xxx.xxx.xxx.4 address? If so, have you tried switching cables?
good luck.

bulliver · 10-22-2004, 03:49 PM

Ok I got it. I ran this command on the server:

Code:

# route add -host 192.168.0.4  dev eth2

Both workstation and laptop are NATed and connected to the internet. I guess before the packets for the laptop were being sent to the workstation because the device for 192.168.0.0 network was set on eth1.

Thanks PEACEDOG...

Peacedog · 10-22-2004, 03:52 PM

Glad you got it sorted, but, I can't take any credit. Good on you mate for sorting it yourself.

ugge · 10-23-2004, 05:33 PM

The main problem here is that both eth1 and eth2 on the server reside on the same network. Without this special routing rule the kernel can't deside where to send the packets, since there are two separate destinations.

This newly added route get precedence before the more general routes from the original configuration.