Networking headbanging!

LizardKing · 31 May 2012 at 12:49

Bit of a weird one this!
Got a new install of CentOS that is unable to ping the internet, dns does resolve an IP and i can ping internal devices ok. Its purely external IP's that fail to ping.

I hear you shouting "no gateway set" or "bad routing table"

And i'd say the same, except the route is set as follows

Code:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.100.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.100.253 0.0.0.0         UG    0      0        0 eth0

ifconfig output

Code:

eth0      Link encap:Ethernet  HWaddr 00:19:DB:6F:55:0E
          inet addr:192.168.100.38  Bcast:192.168.100.255  Mask:255.255.255.0
          inet6 addr: fe80::219:dbff:fe6f:550e/64 Scope:Link
etc

The machine is set with a static IP address.

Anyone got any more ideas? I'm not to great when it comes to routes etc and I'm pretty much stumped.
Thanks

LizardKing · 31 May 2012 at 13:45

SMN said:
tracert get anything good? wget working? i.e. wget http://www.google.com

Unfortunately its the centos minimum install ISO and they have kindly skipped those applications off the install :confused:

But i can test ssh to a test server and it fails with that as well

LizardKing · 31 May 2012 at 14:49

Code:

[root@Hades ~]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=Hades
GATEWAY=192.168.100.253

Already set

I was expecting "default" and wildcards in the route table as well, strange that its not, it was set using
route add default gw 192.168.100.253

As well as defining it in the config files

I've got a feeling its going to be something as simple as that though!

LizardKing · 31 May 2012 at 15:30

Restart / rebooted and reinstalled all no joy! Extremely frustrating!

Just an observation
I've never noticed this before. the difference between specifying "-n" when running the route command

Code:

[root@Hades ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.100.0   *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     1002   0        0 eth0
default         192.168.100.253 0.0.0.0         UG    0      0        0 eth0
[root@Hades ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.100.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.100.253 0.0.0.0         UG    0      0        0 eth0
[root@Hades ~]#

LizardKing · 31 May 2012 at 16:13

Djwayne said:
ok so from the box can you ping the gateway? As thats an internal address from your previous post it should be fine if not and you can ping other internal addresses maybe worth looking at the gateway

Eureka
Pesky firewalls! we define rules against ip address's, this particular address was in a range that was set to deny icmp traffic (as well as ssh) :rolleyes:

Ping was never gonna work

I had corrected the problem this morning but my choice of using ping to test it was what sparked this thread. Lesson learned and only half a day wasted :cool:

Thanks for the input!