# 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](https://git.psi.ch/linux-infra/puppet/-/blob/preprod/data/common.yaml#L538) | [net_client::servers](https://git.psi.ch/linux-infra/puppet/-/blob/preprod/data/common.yaml#L595) | [mta::relays](https://git.psi.ch/linux-infra/puppet/-/blob/preprod/data/common.yaml#L527) |
## 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](https://qip.psi.ch/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.