Unable to login using the nagiosadmin credentials

[sgiworks]

[root@ip-10-1-252-201 ec2-user]# ntpdate -u 0.centos.pool.ntp.org
26 Aug 12:07:43 ntpdate[1322]: no server suitable for synchronization found

[sgiworks]

No blocking of NTP packets

[mcapra]

Are there any internal NTP pools/servers your organization uses? You could try re-configuring your /etc/ntp.conf to use those pools instead of the default CentOS pools.

[sgiworks]

There are no internal NTP pools/servers

[mcapra]

Lets get some more verbose output from ntp. Can you run the following and share the output:

Code: Select all

ntpdate -uvd 0.centos.pool.ntp.org

[sgiworks]

Attached a output from ntpdate

[sgiworks]

Why does it show host found : mail.misbegotten.net

Because when I check on another server is shows correct host details, how can I update it on this server?

[mcapra]

Why does it show host found : mail.misbegotten.net

Because when I check on another server is shows correct host details, how can I update it on this server?

I'm not sure what you mean by "correct host details". When NTP asks for the time from a given pool, something similar to RRDNS will pass the request to one of the servers in the pool. mail.misbegotten.net is just one of those servers in the ntp pool. Getting the same server on 2 separate ntpdate requests against pool.ntp.org is unlikely unless you're querying a specific server.

The real issue is that your machine is trying to get the time from a remote server by transmitting a request but is not receiving a response back.

Are these machines (the functional and non-functional) at the same site with the same ISP? If not, you might inquire with the ISP to see if they're blocking NTP traffic. Again, this is definitely not unheard of since it's a common DOS vector. The ISP at the site might have a specific NTP server it has customers use.

Can you run a traceroute against one of those IPs in the output? traceroute 54.194.18.100 for example. You may need to yum install traceroute since it's not usually included with NLS. Feel free to PM the results of this if they contain sensitive network architecture information.

Other IPs that failed to return the time:

Code: Select all

transmit(54.194.18.100)
transmit(54.229.78.96)
transmit(54.171.104.100)
transmit(54.194.18.100)
transmit(54.229.78.96)
transmit(54.171.104.100)
transmit(54.194.18.100)
transmit(54.229.78.96)
transmit(54.171.104.100)
transmit(54.194.18.100)
transmit(54.229.78.96)
transmit(54.171.104.100)
transmit(54.194.18.100)
transmit(54.229.78.96)
transmit(54.171.104.100)

[sgiworks]

traceroute to 54.194.18.100 failed, NO CONNECTION

[mcapra]

Could you also answer this question:

Are these machines (the functional and non-functional) at the same site with the same ISP? If not, you might inquire with the ISP to see if they're blocking NTP traffic. Again, this is definitely not unheard of since it's a common DOS vector. The ISP at the site might have a specific NTP server it has customers use.

At this point, i'm fairly certain something on the network is filtering/blocking the requests NTP is making from this machine.