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Troubleshooting
Product ConnectXf
Version 3.10
Applies to Administrators
Level Advanced




My client PCs in a different network cannot access the Mail server

Symptoms

  • My server's IP is 172.16.2.38
  • A client having IP address as 172.16.1.2 is unable to access the server, whereas a client having IP address 172.16.2.12 is able to access the server.

Diagnosis

  • Since the server and clients are in two different network ranges, there would be no connection possible between the two, if the server's netmask is not correctly configured.
  • On closer inspection it was observed that the following are the network configurations on the server
cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=172.16.2.38 
NETMASK=255.255.255.0
GATEWAY=172.16.2.1

The Netmask is in Class C. The specified netmask value indicates that only clients in the range of 172.16.2.X can connect to the server.

Resolution

  • The netmask value needs to be changed as follows
cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=172.16.2.38
NETMASK=255.255.0.0
BROADCAST=172.16.255.255
GATEWAY=172.16.2.1

The Netmask is in Class B. The specified netmask value indicates that now clients in the range of 172.16.X.X can connect to the server.

Recommendations

For the impact and dependance of this change on other network elements, please ensure that you get this reviewed and approved by your network team.