The netadmin user is the preferred way of configuring networking The preferred way of administering any of the appliance network configuration is to use the netadmin user account. The netadmin user account enables you to change network, hostname and gateway settings without requiring root privileges. You can also use the netadmin user to reboot the appliance.

This section describes how to set the appliance's hostname and to ensure that it is locally resolvable even if the IP address of the appliance changes.

You can set the hostname locally, or using DHCP/DNS.

Setting the Hostname Locally

If you want the appliance to use the same hostname for all NICs, set the hostname in the /etc/sysconfig/network file. If you want to use different hostnames for individual NICs, set the hostname in the /etc/sysconfig/network-scripts/ifcfg-ethX file. X is the number of the interface, for example eth0.

Add the following line to the file:

HOSTNAME=london01

where london01 is the new hostname.

If you do not have a DNS entry for the host, or you require a failsafe when DNS is unavailable, then enter the hostname and FQDN in the etc/hosts file. Use the appliance's IP address if this is unlikely to change, or a loopback IP address other than 127.0.0.1 (which can interfere with the resolution of localhost and localdomain).

The following example uses london01 as the hostname, london.com as the domain name, and 192.168.0.100 as the IP address. Add only one of the example entries.

127.0.0.1           localhost.localdomain localhost
::1                 localhost6.localdomain6 localhost6

### Enter either this line if the IP address is known
192.168.0.100       london01.london.com london01

### Or this line to use a loopback address
127.0.0.2           london01.london.com london01

The following example uses the same host and domain names as above and shows commands to enter to ensure that the hostname is set correctly:

[tideway@london01 ~]$ hostname
london01
[tideway@london01 ~]$ hostname --domain
london.com
[tideway@london01 ~]$ hostname --fqdn
london01.london.com
[tideway@london01 ~]$ ping `hostname`
PING london01 (192.168.0.100) 56(84) bytes of data.
64 bytes from london01 (192.168.0.100): icmp_seq=1 ttl=64 time=0.050 ms
64 bytes from london01 (192.168.0.100): icmp_seq=2 ttl=64 time=0.047 ms
64 bytes from london01 (192.168.0.100): icmp_seq=3 ttl=64 time=0.042 ms
64 bytes from london01 (192.168.0.100): icmp_seq=4 ttl=64 time=0.041 ms

--- london01 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3002ms
rtt min/avg/max/mdev = 0.041/0.045/0.050/0.003 ms
[tideway@london01 ~]$

Setting the Hostname Using DHCP/DNS

Some networks are configured so that you can set your own hostname and update the DHCP and DNS servers accordingly.

To enable this for all NICs, set the DHCP_HOSTNAME in the /etc/sysconfig/network file. To enable this for individual NICs, set the DHCP_HOSTNAME in the /etc/sysconfig/network-scripts/ifcfg-ethX file. X is the number of the interface, for example eth0.

The following example uses london01 as the hostname and london.com as the domain name.

DHCP_HOSTNAME=london01.london.com

When the appliance renews its IP address with the DHCP server, the DHCP server will also update the DNS server with the hostname and IP address of the appliance.

Diagnosing Hostname Problems

Some issues are indicative of incorrectly configured hostnames.

Visualizations and Export do not Display

This problem can be identified if you see a 500 Error - Internal Server Error! page in the UI when
attempting to load visualizations. You will also see the following error message in $TIDEWAY/tomcat/logs/catalina.out:

java.net.UnknownHostException: local_hostname: local_hostname

where local_hostname is the hostname set on the machine.

To resolve this problem, see Setting the Hostname Locally.

Cannot Access the UI – 500 Internal Server Error

This error can have many causes, as it results from one or more of the tideway services failing to start. A common cause however is that localhost cannot be resolved. If this is the case errors of the following form are displayed when restarting the tideway services.

[current date/time] [error] couldn't resolve WKServer address
[current date/time] [error] Couldn't resolve hostname for WebKit Server