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I'm working with a minimal installation of RHEL 6.

When I first turned this machine on, it couldn't ping anybody. It turned out that I needed to add the GATEWAY under /etc/sysconfig/networking and configure /etc/sysconfig/network-scripts/ifcfg-eth0 to point to the gateway and boot on start using DHCP.

As of now, I can access any other machine on the local network; I can even SSH into the machine I'm working with. What I still cannot do is access anything outside of the local network; I can't access the internet.

Consider:

[root@dbrepa ~]# ping dev-108a -c 4
PING dev-108a.some.domain.net (192.168.108.119) 56(84) bytes of data.
64 bytes from dev-108a.some.domain.net (192.168.108.119): icmp_seq=1 ttl=64 time=0.276 ms
64 bytes from dev-108a.some.domain.net (192.168.108.119): icmp_seq=2 ttl=64 time=0.249 ms
64 bytes from dev-108a.some.domain.net (192.168.108.119): icmp_seq=3 ttl=64 time=0.250 ms
64 bytes from dev-108a.some.domain.net (192.168.108.119): icmp_seq=4 ttl=64 time=0.259 ms

--- dev-108a.some.domain.net ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3000ms
rtt min/avg/max/mdev = 0.249/0.258/0.276/0.019 ms



[root@dbrepa ~]# ping example.com
PING example.com (93.184.216.119) 56(84) bytes of data.
^C
--- example.com ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, time 6741ms



[root@dbrepa ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.108.0   *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     1002   0        0 eth0
default         dc-108a.cool.do 0.0.0.0         UG    0      0        0 eth0

dev-108a is a server on our network, and as you can see I can speak to it with no issues. However, for example.com, I can retrieve the IP address from the DNS for example.com, in my case 93.184.216.119, but then ping just hangs. It's still working---it's still sending out packets, but none of them will get replies and this process will continue until kill.

As per the comments, I've brought the local firewall down (with service iptables stop) to no effect.

What could be going wrong? How am I getting an IP address while not able to access it?


I know that I am missing several core UNIX tools; I am at least missing:

  • man
  • dig
  • traceroute
  • telnet
  • wget
share|improve this question
    
Please, provide output of 'route' command –  Nikolay Aug 8 '13 at 20:07
    
name resolution is provided by DNS, even through ping. Pings could be filtered, yet DNS lookups will still go through –  Keltari Aug 8 '13 at 20:16
    
@Nikolay Thanks, and done. Note that dc-108a is our domain controller. –  Sean Allred Aug 8 '13 at 20:16
    
@Keltari yay learning! What could be filtering the pings? I brought the local firewall down (with service iptables stop) to no effect. (I'll edit that into my Q.) –  Sean Allred Aug 8 '13 at 20:17
    
@vermiculus. Could you ping your default router and see if you able to reach it? –  Nikolay Aug 8 '13 at 20:20

1 Answer 1

'What could be going wrong? How am I getting an IP address while not able to access it?"

You are getting IP address because your computer can successfully reach the DNS server which your computer was instructed to use.

To make sure you can communicate to the outside of the network you need to make sure you have correct network settings including IP address, subnet mask and router.

If there is firewall operating at the gateway you have to make sure your computer was granted access from inside the network to the outside.

If can provide output of the following commands it will be possible to debug it faster:

ifconfig -a
route
share|improve this answer
    
I think you may be on to something with the subnet mask. Do you know which file that is usually stored in? –  Sean Allred Aug 8 '13 at 20:20
    
Check if there is something in the /etc/sysconfig/network-scripts/ –  Nikolay Aug 8 '13 at 20:22
    
Not that I can see. –  Sean Allred Aug 8 '13 at 20:25
    
Good. Open ifcfg-eth0 and see what is inside. –  Nikolay Aug 8 '13 at 20:27
    
Everything looks normal. Do I need to tell it anything else? (That's the entire contents of the file.) –  Sean Allred Aug 8 '13 at 20:28

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