Poul Moller wrote:
Hi all,
I'm having a simple network but a strange problem that need some experts
eyes. My FC2 server that serves as a LTSP server has two "legs" in
different networks:
eth0: 10.0.0.1/24 (student network for thin clients)
eth1: 192.168.1.10/24 (school network with Internet access router at
192.168.1.1)
Here come the challege: On the server I can ping all hosts EXCEPT the
router 192.168.1.1 (the default gateway) ????????? The router is
perfectly alive and all hosts on the 192.168.1.0 net has Internet
access except the FC2 server. There must something I completely miss.
NOTE: the last line (default gw) in the "netstat -r" command takes 10
sec to display !!!!!!!!!
Any hint is greatly appreciated
Poul
Any possibility that a firewall is configured? Use
/sbin/iptables -L -v -n
to see the firewall rules.
Another debugging trick is to check whether the arp request for
the gateway is being comleted. Run ping in one window (or on one
console, or in the background) while you check arp in another window.
Or, just check arp immediately after you stop ping.
/sbin/arp -a -n
You're looking for an entry giving the default router's IP and
MAC address. An "incomplete" entry means that the trouble is
with arp...your server/router asked for the mac address of the
internet gateway but was not able to read a response successfully.
No entry at all would indicate that your server/router did not
even attempt to send a packet to the gateway and the difficulty
is with the routing tables.
[root@odin root]# cat /proc/sys/net/ipv4/ip_forward
1
[root@odin root]# netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt
Iface
10.0.0.0 * 255.255.255.0 U 0 0 0
eth0
192.168.1.0 * 255.255.255.0 U 0 0 0
eth1
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 192.168.1.1 0.0.0.0 UG 0 0 0
eth1
[root@odin root]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=odin
FORWARD_IPV4=true
NOZEROCONF=yes
GATEWAY=192.168.1.1
GATEWAYDEV=eth1
[root@odin root]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Intel Corp.|82547GI Gigabit Ethernet Controller
DEVICE=eth0
BOOTPROTO=none
BROADCAST=10.0.0.255
HWADDR=00:50:8D:E3:02:F4
IPADDR=10.0.0.1
NETMASK=255.255.255.0
NETWORK=10.0.0.0
ONBOOT=yes
TYPE=Ethernet
USERCTL=no
PEERDNS=no
IPV6INIT=no
GATEWAY=192.168.1.1
[root@odin root]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
# 3Com Corporation|3c905C-TX/TX-M [Tornado]
DEVICE=eth1
ONBOOT=yes
BOOTPROTO=none
IPADDR=192.168.1.10
NETMASK=255.255.255.0
HWADDR=00:0A:5E:22:AE:D6
USERCTL=no
PEERDNS=no
GATEWAY=192.168.1.1
TYPE=Ethernet
IPV6INIT=no
GATEWAYDEV=eth1
[root@odin root]# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
--- 192.168.1.1 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1000ms
[root@odin root]# ping 192.168.1.50
PING 192.168.1.50 (192.168.1.50) 56(84) bytes of data.
64 bytes from 192.168.1.50: icmp_seq=0 ttl=127 time=0.525 ms
64 bytes from 192.168.1.50: icmp_seq=1 ttl=127 time=0.218 ms
--- 192.168.1.50 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.218/0.371/0.525/0.154 ms, pipe 2
