Users Guide

Troubleshooting Your Application | Troubleshooting
OMNM 6.5.3 User Guide 701
Communication Problems
Firewalls may interfere with necessary communication between elements within or monitored by
your system. Best practice when installing is to bring the firewall down, install, then once you have
confirmed the installation runs, bring the firewall up with the appropriate ports open. (See
Resolving Port Conflicts on page 712, also see Ports Used on page 1021 and Ports and Application
To Exclude from Firewall
on page 1034.)
Managed devices often have Access Control Lists (ACLs) for management traffic. Best practice is
to use a management VLAN or subnet. Note also that in-path devices may filter management
traffic creating an obstacle to management messages. Overlapping address spaces may also
complicate network management. Identifying such “DMZs” and overlaps is part of network
analysis.
Preventing Discovery Problems
Ensure your firewall is not blocking network access to equipment you are trying to discover. The
following describes more preventive practices to do when you discover a mixed vendor/mixed class
network.
ICMP (Ping)
You can ping devices from a shell or the Network Tools portlet to insure it’s up and online.
Telnet/SSH
1 Manually telnet or SSH connect to a device to verify that you have the correct authentication
information (although Discovery Profiles’
Inspect function does this too).
NOTE:
Later versions of Windows do not include telnet by default. In addition to free telnet programs you can
download and install, like PuTTY, you can open a shell (Start > Run
cmd ) and type oware to get telnet
capabilities. Also: Use SSH v2 for Dell devices.
2 If you know the device, look at its configuration file and verify that the SNMP community
string is correct.
3 Discover the device.
4 If there are any problems with any devices, then ping them, and/or telnet to problem devices
and verify that telnet works/authentication is good.
5 If SNMP problems arise, use this application’s MIB browser tool to troubleshoot them.
To verify SNMP and WMI connections are working between your system and the devices in the
network, use the following tools:
SNMP
1 Open MIB Browser in the web client’s Network Tools portlet, or by right-clicking the device.
2 Select RFC1213, system, from the RFC Standard Mibs branch
3 If necessary, fill out the Authentication tab
4 Select the device tab and information will populate as soon as the query is answered.