Users Guide
Setup and Administration 55
Firewall Configuration on Systems Running Supported Red Hat Enterprise Linux
Operating Systems
If you enable firewall security when installing Red Hat Enterprise Linux,
the SNMP port on all external network interfaces is closed by default.
To enable SNMP management applications such as IT Assistant to discover
and retrieve information from Server Administrator, the SNMP port on at
least one external network interface must be open. If Server Administrator
detects that the SNMP port is not open in the firewall for any external
network interface, Server Administrator displays a warning message and logs
a message to the system log. See "Ports" for additional information.
You can open the SNMP port by disabling the firewall, opening an entire
external network interface in the firewall, or opening the SNMP port for at
least one external network interface in the firewall. You can perform this
action before or after Server Administrator is started.
To open the SNMP port using one of the previously described methods,
perform the following steps:
1
At the Red Hat Enterprise Linux command prompt, type
setup
and
press <Enter> to start the Text Mode Setup Utility.
NOTE: This command is available only if you have performed a default
installation of the operating system.
The
Choose a Tool
menu appears.
2
Select
Firewall Configuration
using the down arrow and press <Enter>.
The
Firewall Configuration
screen appears.
3
Select the
Security Level
. The selected
Security Level
is indicated by an
asterisk.
NOTE: Press <F1> for more information about the firewall security levels.
The default SNMP port number is 161. If you are using the X Windows GUI,
pressing <F1> may not provide information about firewall security levels on
newer versions of the Red Hat Enterprise Linux operating system.
a
To disable the firewall, select
No firewall
or
Disabled
and go to step 7.
b
To open an entire network interface or the SNMP port, select
High,
Medium,
or
Enabled
.
4
Select
Customize
and press <Enter>.
The
Firewall Configuration - Customize
screen appears.