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3 Replies Latest reply: Feb 26, 2013 9:02 PM by 993094 RSS

Could not ping and access a server after changing its ip

993094 Newbie
Currently Being Moderated
I could not ping and access a (destination) machine from another (source) machine after changing destination machine ip although I modified hosts file and hosts map in the source machine
I can access the destionation using IP. This problem happened in case of using hostname not IP

My source machine is omcsp4 (192.6.6.40) and destination machine is omcsp8 (10.57.217.80).
Here is the host file for two machines:

omcsp4
hosts:
10.57.217.80     omcsp8
127.0.0.1     localhost     
192.6.6.40     omcsp4     omcsp4.localdomain omc_splat omc_4gl omc_pm loghost
#Firewall
192.6.6.200 FIREWALL

hosts.equiv
omcsp4
omcsp8

omcsp8
hosts:
#
# Internet host table
#
127.0.0.1     localhost     
10.57.217.80     omcsp8     omcsp8.localdomain omc_splat omc_4gl omc_pm loghost
192.6.6.40 omcsp4

hosts.equiv:
omcsp8
omcsp4

Here's logfile when I try to ssh on both machine
hostname
omcsp4
bash-3.00# grep omcsp8 h /etc/hosts
10.57.217.80 omcsp8
bash-3.00# ypcat hosts | grep omcsp8
10.57.217.80 omcsp8
bash-3.00# ping -a omcsp8
no answer from omcsp8(192.6.6.180)
bash-3.00# ping 10.57.217.80
10.57.217.80 is alive
bash-3.00# ssh 10.57.217.80
The authenticity of host '10.57.217.80 (10.57.217.80)' can't be established.
RSA key fingerprint is c7:d6:32:81:bb:6e:b5:f0:d0:5f:9f:05:f4:6e:be:3f.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.57.217.80' (RSA) to the list of known hosts.
Password:
Last login: Thu Feb 21 19:42:08 2013 from omcsp1
Sun Microsystems Inc. SunOS 5.10 Generic January 2005
You have new mail.
# hostname
omcsp8
# ping omcsp4
omcsp4 is alive
# ifconfig -a
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
ce0: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
inet 10.57.217.80 netmask ffffff00 broadcast 10.57.217.255
ether 0:14:4f:67:32:cb
#
#
#
# exit
Connection to 10.57.217.80 closed.
bash-3.00# hostnae me
omcsp4
bash-3.00# id
uid=0(root) gid=0(root)
bash-3.00# cd /var/yp
bash-3.00# make hsost osts
updated hosts
pushed hosts
bash-3.00# ping -a omcsp8
no answer from omcsp8(192.6.6.180)
bash-3.00# grep omcsp8 /etc/hosts
10.57.217.80 omcsp8
bash-3.00# ypcat hosts | grep omcsp8
10.57.217.80 omcsp8

Edited by: 990091 on Feb 25, 2013 6:10 PM
I've change from "server" to "machine" to avoid misunderstand
  • 1. Re: Could not ping and access a server after changing its ip
    rukbat Guru Moderator
    Currently Being Moderated
    Why would ping be enabled on a server?
    That is a security vulnerability.

    You may need to spend some time with your favorite web search site (for example: Google) researching why and how to enable ping or whether you even should enable ping.
  • 2. Re: Could not ping and access a server after changing its ip
    993094 Newbie
    Currently Being Moderated
    Update for this situation
    omcsp4
    IP: 192.6.6.40
    omcsp8
    old IP: 192.6.6.180
    new IP: 10.57.217.80

    When I ping from omcsp4 to omcsp8, there's no answer and the hostname is resolved as *192.6.6.180* which is the old IP. But in hosts file, the IP is the new one.
    omcsp4:omcadmin > ping -a omcsp8
    no answer from omcsp8(192.6.6.180)
    omcsp4:omcadmin > grep omcsp8 /etc/hosts
    10.57.217.80 omcsp8
    omcsp4:omcadmin > ypcat hosts | grep omcsp8
    10.57.217.80 omcsp8     
    omcsp4:omcadmin > ping 10.57.217.80
    10.57.217.80 is alive

    These above operations show that the hosts file and NIS are both updated with the new IP address of omcsp8. But when i ping omcsp8 (by name) it returns the old IP address. So the question is from where the system omcsp4 resolve the hostname omcsp8???
  • 3. Re: Could not ping and access a server after changing its ip
    993094 Newbie
    Currently Being Moderated
    Finally I found that problem.
    The reason is I haven't restarted network service on the source machine. So that the source machine still resolves the destination machine's name as the old address which is not available since it is changed to the new one.
    I've restarted the network service on source machine by this command and it works fine:
    +# svcadm restart network/physical+

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