[Help] My Network cannot Ping Gateway!

[andersonlich]

I have no idea at all, but i wish someone can help me bout this.. cause im noobs bout linux networks. i have problem in network on ubuntu server 6.10, when i ping my other local network it is reply as you can see,

root@idc:/etc/network# ping 10.64.10.35
PING 10.64.10.35 (10.64.10.35) 56(84) bytes of data.
64 bytes from 10.64.10.35: icmp_seq=1 ttl=128 time=14.1 ms
64 bytes from 10.64.10.35: icmp_seq=2 ttl=128 time=0.400 ms
64 bytes from 10.64.10.35: icmp_seq=3 ttl=128 time=0.260 ms
64 bytes from 10.64.10.35: icmp_seq=4 ttl=128 time=0.328 ms

but when i ping my ipaddress gateway it isn't reply :

root@idc:/etc/network# ping 10.64.10.33
PING 10.64.10.33 (10.64.10.33) 56(84) bytes of data.

--- 10.64.10.33 ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5001ms

this is my ifconfig eth0

root@idc:/etc/network# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:07:E9:F3:34:95
          inet addr:10.64.10.36  Bcast:10.64.10.47  Mask:255.255.255.240
          inet6 addr: fe80::207:e9ff:fef3:3495/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1108 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1049 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:117349 (114.5 KiB)  TX bytes:289418 (282.6 KiB)

and my netstat -rn

root@idc:/etc/network# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.64.10.32     0.0.0.0         255.255.255.240 U         0 0          0 eth0
0.0.0.0         10.64.10.33     0.0.0.0         UG        0 0          0 eth0

and this is my /etc/networks/interfaces

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 10.64.10.36
        netmask 255.255.255.240
        network 10.64.10.32
        broadcast 10.64.10.47
        gateway 10.64.10.33
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 10.64.2.2 10.64.2.18

fiuhhh.. i have no idea bout.

some body can help me?

thanks..

anderson

[dilbert]

I don't know almost nothing about gateways, but ist it ok that your gateway has IP address 0.0.0.0?

I believe that this is a non-functional default address that is set only temporarily until for example a DHCP server sets the final address.

Maybe there is a DHCP server that haven't been started properly or somethimg like that.

Another question is the netmask. The last byte 240 (= 1111 0000) isn't a bit restrictive?

You could check the arptables of each box with "arp -en" to see what other connection each box sees. That is sometimes helpful to get a clue when ping and arpings are failing for no apparent reason.

[andersonlich]

root@idc:~# arp -ne
Address                  HWtype  HWaddress           Flags Mask            Iface
10.64.10.35              ether   00:11:2F:8E:E6:A7   C                     eth0
10.64.10.34              ether   00:0E:A6:37:FF:35   C                     eth0

this is result after i run the command of "arp -ne", any body can explain what does it means? and i my server can't ping my gateway address, so i cant connect to the internet or outside my LAN.

[dilbert]

It says that your neighboring computers that your computer can talk with, are 10.64.10.35 and 10.64.10.34. Your computer can see them over its (only active) Ethernet port eth0.

Your computer doesn't see x.x.x.33.

I think it would need to see x.x.x.32 as your gateway (properly configured what I'm not sure) to be able to see x.x.x.33.

To get a picture of your LAN, you get on every computer, run "ifconfig" and compare IP address and HWaddress (= MAC address) with the figures from "arp -en". You can run "arp -en" on these computers as well.

Now, "arp -en" says that there are 3 computers in your LAN.

This arp table is populated by arpings. Every time you send a new ping after some time, the network launches implicitely an arping before that. That arping matches IP addresses with Ethernet MAC addresses, because the Ethernet protocol doesn't know the IP protocol and works only with MAC address.
A subsequent ping then looks up the arp table to know to which MAC address to send the Ethernet packets when only the IP address is given.

So, no entry in arp table means no packets are sent off.