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Old 11-01-2015, 03:52 PM   #1
willc86
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Where to start diagnosing my unix server? Cant not ping internal networks


Hello everyone,

I am just trying to go in the steps to diagnose my server. I added kubuntu to my laptop, installed open ssh client and server

the host name is shadow. So, from different unix and windows machine, I can not ping shadow

and from shadow, I can not ping to any box, whether it is unix and/or windows. So, pretty much both ways, I can not ping to or from shadow.

Also, when I do arp -a it only reveals my gateway which is 192.168.0.1
or is there another command to reveal all other IPs on the network?
 
Old 11-01-2015, 04:25 PM   #2
yancek
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The command below should show any machines which are up.

Quote:
nmap -sP 192.168.0.1/24
 
Old 11-01-2015, 07:39 PM   #3
chrism01
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Its also possible that the machines are set to drop ICMP pkts used by ping.
You can try http://linux.die.net/man/1/tcptraceroute or the telnet client.
 
Old 11-01-2015, 11:08 PM   #4
frieza
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what is the IP of shadow? and are you pinging it by IP address or by name?

If by name, by what mechanism are you informing your computer that that name shadow is a host name that belongs to an IP address (and by extension the IP address that belongs to that name), do you have a host file, NIS, internal DNS? basically, how, if at all are internal network host names resolved to IP addresses within your network?

Simply naming the machine 'shadow' does not mean that other machines on the network have access to that information, you need some form of address resolution, such as DNS, or NIS

I would start by looking up the address of shadow and pinging the IP, if that works then your issue is name resolution, if it doesn't then check the firewall on shadow to make sure it isn't discarding ICMP packets as suggested by chrism01
 
Old 11-13-2015, 05:52 AM   #5
willc86
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thanks for your reply!

I am going to try that. If it is a DNS issue, can I install samba on it to make it compliant with windows standards? I am just practicing creating a back up server incase my main one fails. I have a server called venus, and if venus ever fails, I would like shadow to take over until it is back up.

How would I check on the fire wall to see if it drops ICMP packets? or I can easily google that information? Does this involve IP tables?

thanks!
 
Old 11-13-2015, 10:36 AM   #6
serverpoint.com
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I think the fail over is depends on what service you are running inside the server.
 
Old 11-14-2015, 01:03 AM   #7
frieza
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Quote:
Originally Posted by willc86 View Post
thanks for your reply!

I am going to try that. If it is a DNS issue, can I install samba on it to make it compliant with windows standards? I am just practicing creating a back up server incase my main one fails. I have a server called venus, and if venus ever fails, I would like shadow to take over until it is back up.

How would I check on the fire wall to see if it drops ICMP packets? or I can easily google that information? Does this involve IP tables?

thanks!
if it's all linux i'd try either BIND9(dns) or and NIS server
 
Old 11-16-2015, 03:03 AM   #8
chrism01
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Quote:
How would I check on the fire wall to see if it drops ICMP packets? or I can easily google that information? Does this involve IP tables?
Yep, check the iptables cfg eg /etc/sysconfig/iptables or equiv. This assumes no intervening switch etc that may be doing that...
 
  


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