Red Hat NETWORK PROXY SERVER 3.7 -, Installation Manual

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Chapter 6. Troubleshooting 27
6.5. Host Not Found/Could Not Determine FQDN
Because RHN configuration files rely exclusively on fully qualified domain names (FQDN), it is
imperative key applications are able to resolve the name of the RHN Proxy Server into an IP address.
Red Hat Update Agent
,
Red Hat Network Registration Client
, and the Apache HTTP Server are
particularly prone to this problem with the RHN applications issuing errors of "host not found" and
the Web server stating "Could not determine the server’s fully qualified domain name" upon failing to
start.
This problem typically originates from the
/etc/hosts
file. You may confirm this by examining
/etc/nsswitch.conf
, which defines the methods and the order by which domain names are re-
solved. Usually, the
/etc/hosts
file is checked first, followed by Network Information Service (NIS)
if used, followed by DNS. One of these has to succeed for the Apache HTTP Server to start and the
RHN client applications to work.
To resolve this problem, identify the contents of the
/etc/hosts
file. It may look like this:
127.0.0.1 this_machine.example.com this_machine localhost.localdomain.com localhost
First, in a text editor, remove the offending machine information, like so:
127.0.0.1 localhost.localdomain.com localhost
Then, save the file and attempt to re-run the RHN client applications or the Apache HTTP Server. If
they still fail, explicitly identify the IP address of the Proxy in the file, such as:
127.0.0.1 localhost.localdomain.com localhost
123.45.67.8 this_machine.example.com this_machine
Replace the value here with the actual IP address of the Proxy. This should resolve the problem. Keep
in mind, if the specific IP address is stipulated, the file will need to be updated when the machine
obtains a new address.
6.6. Connection Errors
If your are experiencing problems that you believe to be related to failed connections, follow these
measures:
•
Confirm the correct
rhn-org-httpd-ssl-key-pair-
MACHINE_NAME-VER-REL
.noarch.rpm
is installed on the RHN Proxy Server and the corresponding
rhn-org-trusted-ssl-cert-*.noarch.rpm
or raw CA SSL (client) certificate is installed
on all client systems.
•
Verify the client systems are configured to use the appropriate certificate.
•
If using one or more RHN Proxy Servers, ensure each Proxy’s SSL certificate is prepared correctly.
If using the RHN Proxy Server in conjunction with an RHN Satellite Server the Proxy should have
both its own server SSL key-pair and CA SSL (client) certificate installed, since it will serve in
both capacities. Refer to the SSL Certificates chapter of the RHN Client Configuration Guide for
specific instructions.
•
If the RHN Proxy Server is connecting through an HTTP Proxy, make sure the URL listed is valid.
For instance, the HTTP Proxy URL field should not contain references to protocols, such as http://
or https://. Only the hostname and port should be included in the form hostname:port, such as
corporate_gateway.example.com:8080.
•
Make sure client systems are not using firewalls of their own blocking required ports, as identified
in Section 2.4 Additional Requirements .