IP Address Change

An IP address change needs following steps

I stay in the same firewall zone

change IP address
restart networking or reboot

I move out to the DMZ

change IP address
change nameservers (DNS)
change timeservers (NTP)
change mail relay (SMTP)
restart all these services or reboot

One day when there is Puppet available in the DMZ then it will handle the later part.

Networking Infrastructure

Zone	Name Server (DNS)	Time Server (NTP)	Mail Relay (SMTP)
default	`129.129.190.11` `129.129.230.11`	`pstime1.psi.ch` `pstime2.psi.ch` `pstime3.psi.ch`	`smtpint.psi.ch`
dmz/tier3	`192.33.120.5` `192.33.121.5`	`dmztime1.psi.ch` `dmztime2.psi.ch`	`smtpdmz.psi.ch`
source	networking::nameservers	net_client::servers	mta::relays

Select the Network Interface Device

To see what network interfaces are available, use

ip link show

(all RHEL versions) or

nmcli device status

(starting from RHEL8)

Edit the IP Configuration of a Network Interface

The configuration is done in the file /etc/sysconfig/network-scripts/ifcfg-$DEVICE.

An example configuration for a static IP address as set up by the kickstart file looks like:

TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
IPADDR=129.129.187.41
PREFIX=24
GATEWAY=129.129.187.1
DNS1=129.129.190.11
DNS2=129.129.230.11
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=eui64
NAME=ens160
UUID=db60a82b-2a4c-4077-b4c1-5dd0e2476be1
DEVICE=ens160
ONBOOT=yes

Here you need to change the IPADDR and possibly the GATEWAY and rarely the PREFIX. The last two can be looked up in QIP, but the usual pattern is *.*.*.1 for the gateway and a prefix of 24.

When moving to a different zone, then you need also to adapt the DNS servers.

If you alterntively change to DHCP, then you can use this:

TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=dhcp
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=eui64
NAME=ens160
UUID=b5e9cf25-056d-4acb-958c-7a443300e1e1
DEVICE=ens160
ONBOOT=yes

This will be active after boot or

systemctl restart NetworkManager

(RHEL8) or

systemctl restart network.service

(RHEL7)

Note if you are in need of a new UUID run uuidgen.

Change Time Server (NTP)

Adapt in the file /etc/chrony.conf the server list and the initstepslew config with the respective time servers.

systemctl restart chronyd.service

applies the changes.

Change Server for Outgoing Mails

This depends on the software running on the system.

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