Network Configuration Lab

1. Examine the Network Configuration

In this lab, you examine the network configuration of the current system to identify the current network interfaces and basic network addresses.

Display the current IP address and netmask for all interfaces.

[student@server1 ~]$ ip addr
1:lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:0:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:4:00:00:00:0b brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.11/24 brd 192.168.0.255 scope global dynamic eth0
       valid_lft 12704sec preferred_lft 12704sec
    inet6 fe80::5054:ff:fe00:b/64 scope link
       valid_lft forever preferred_lft forever

Display the statistics for the eth0 interface.

[student@server1 ~]$ ip -s link show eth0
2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 52:4:00:00:00:0b brd ff:ff:ff:ff:ff:ff
    RX:bytes  packets  errors  dropped overrun mcast
    418398     4588     0       0       0       0
    TX:bytes  packets  errors  dropped carrier collsns
    360733     1730     0       0       0       0

Display the routing information.

[student@server1 ~]$ ip route
default via 192.168.0.254 dev eth0  proto static  metric 1024
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.101

Verify that the router is accessible.

[student@server1 ~]$ ping -c3 192.168.0.254
PING 192.168.0.254 (192.168.0.254) 56(84) bytes of data.
64 bytes from 192.168.0.254:icmp_seq=1 ttl=64 time=0.489 ms
64 bytes from 192.168.0.254:icmp_seq=2 ttl=64 time=0.510 ms
64 bytes from 192.168.0.254:icmp_seq=3 ttl=64 time=0.458 ms

--- 192.168.0.254 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 0.458/0.485/0.510/0.033 ms

Show all the hops between the local system and instructor.example.com.

[student@server1 ~]$ tracepath instructor.example.com
 1: instructor.example.com                                 0.522ms !H
     Resume:pmtu 65535

Display the listening TCP sockets on the local system.

[student@server1 ~]$ ss -lt
State      Recv-Q Send-Q      Local Address:ort          Peer Address:Port
LISTEN     0      128                     *:5630                    *:*
LISTEN     0      128                     *:unrpc                   *:*
LISTEN     0      128                     *:sh                      *:*
LISTEN     0      100             127.0.0.1:mtp                     *:*
LISTEN     0      128                    ::sunrpc                  :::*
LISTEN     0      128                    ::ssh                     :::*
LISTEN     0      128                    ::33079                   :::*
LISTEN     0      100                   :1:smtp                    :::*

2. Configure Network Settings with `nmcli`

In this lab, you configure network settings using nmcli, and you convert a system from DHCP to a static configuration.

Access your server1.example.com VM using the GUI console and log in as student.

View network settings using nmcli.

Show all connections.

[student@server1 ~]$ nmcli con show
NAME         UUID                                  TYPE            DEVICE
System eth0  5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03  802-3-ethernet  eth0

Display all configuration settings for the active connection.

[student@server1 ~]$ nmcli con show "System eth0"
connection.id:                         System eth0
connection.uuid:                       5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
connection.interface-name:             eth0
connection.type:                       802-3-ethernet
connection.autoconnect:                yes
connection.timestamp:                  1394813303
connection.read-only:                  no
connection.permissions:
...
IP4.ADDRESS[1]:                        ip = 192.168.0.11/24, gw = 192.168.0.254
IP4.DNS[1]:                            192.168.0.254
IP4.DOMAIN[1]:                         example.com
...

Show device status.

[student@server1 ~]$ nmcli dev status
DEVICE  TYPE      STATE      CONNECTION
eth0    ethernet  connected  System eth0
lo      loopback  unmanaged  --

Display the settings for the eth0 device.

[student@server1 ~]$ nmcli dev show eth0
GENERAL.DEVICE:                        eth0
GENERAL.TYPE:                          ethernet
GENERAL.HWADDR:                        52:54:00:00:00:0B
GENERAL.MTU:                           1500
GENERAL.STATE:                         100 (connected)
GENERAL.CONNECTION:                    System eth0
GENERAL.CON-PATH:                      /org/freedesktop/NetworkManager/ActiveConnection/1
WIRED-PROPERTIES.CARRIER:              on
IP4.ADDRESS[1]:                        ip = 192.168.0.11/24, gw = 192.168.0.254
IP4.DNS[1]:                            192.168.0.254
IP4.DOMAIN[1]:                         example.com
IP6.ADDRESS[1]:                        ip = fe80::5054:ff:fe00:b/64, gw = ::

As the root user create a static connection with the same IPv4 address, network prefix, and default gateway. Name the new connection static-eth0.

Since access to your machine is provided over the primary network connection, setting incorrect values during network configuration may make your machine unreachable. This is why you should run this lab from the GUI console.

[student@server1 ~]$ sudo nmcli con add con-name "static-eth0" ifname eth0 type ethernet ip4 192.168.0.11/24 gw4 192.168.0.254
Connection 'static-eth0' (f3e8dd32-3c9d-48f6-9066-551e5b6e612d) successfully added.

Modify the new connection to add the DNS setting.

[student@server1 ~]$ sudo nmcli con mod "static-eth0" ipv4.dns 192.168.0.254

View all connections.

[student@server1 ~]$ nmcli con show
NAME         UUID                                  TYPE            DEVICE
static-eth0  f3e8dd32-3c9d-48f6-9066-551e5b6e612d  802-3-ethernet  --
System eth0  5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03  802-3-ethernet  eth0

View the active connection.

[student@server1 ~]$ nmcli con show --active
System eth0  5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03  802-3-ethernet  eth0

Activate the new connection.

[student@server1 ~]$ sudo nmcli con up "static-eth0"
Connection successfully activated (D-Bus active path:/org/freedesktop/NetworkManager/ActiveConnection/3)

View the active connection.

[student@server1 ~]$ nmcli con show --active
NAME         UUID                                  TYPE            DEVICE
static-eth0  f3e8dd32-3c9d-48f6-9066-551e5b6e612d  802-3-ethernet  eth0

Test the connectivity using the new network addresses.

Verify the IP address.

[student@server1 ~]$ ip addr show eth0
2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:4:00:00:00:0b brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.11/24 brd 192.168.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe00:b/64 scope link
       valid_lft forever preferred_lft forever

Verify the default gateway.

[student@server1 ~]$ ip route
default via 192.168.0.254 dev eth0  proto static  metric 1024
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.101

Ping the DNS address.

[student@server1 ~]$ ping -c3 192.168.0.254
PING 192.168.0.254 (192.168.0.254) 56(84) bytes of data.
64 bytes from 192.168.0.254:icmp_seq=1 ttl=64 time=0.419 ms
64 bytes from 192.168.0.254:icmp_seq=2 ttl=64 time=0.598 ms
64 bytes from 192.168.0.254:icmp_seq=3 ttl=64 time=0.503 ms

--- 192.168.0.254 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 0.419/0.506/0.598/0.077 ms

Configure the original connection so that it does not start at boot and verify that the static connection is used when the system reboots.
1. Disable the original connection from auto starting at boot.
  [student@server1 ~]$ sudo nmcli con mod "System eth0" connection.autoconnect no
2. Reboot the system.
  [student@server1 ~]$ reboot

Once the system has rebooted, log back in and view the active connection.

[student@server1 ~]$ nmcli con show --active
NAME         UUID                                  TYPE            DEVICE
static-eth0  f3e8dd32-3c9d-48f6-9066-551e5b6e612d  802-3-ethernet  eth0

On the desktop1.example.com system as root, reset the server1.example.com system to revert all changes:
```
[root@desktop1 ~]# lab-resetvm
```

3. Edit Network Configuration Files

In this lab, you edit network configuration files and add an additional network address to each system.

Log in to server1.example.com via the console GUI as root and edit the /etc/sysconfig/network-scripts/ifcfg-eth0 to disable dhcp, set a static IP for 192.168.0.101, and add an additional address of 192.168.0.201/24.

Append an entry to the file to specify the IPv4 address.

[root@server1 ~]# sed -i "s/dhcp/none/" /etc/sysconfig/network-scripts/ifcfg-eth0
[root@server1 ~]# echo "IPADDR1=192.168.0.101" >> /etc/sysconfig/network-scripts/ifcfg-eth0
[root@server1 ~]# echo "IPADDR2=192.168.0.201" >> /etc/sysconfig/network-scripts/ifcfg-eth0

Append an entry to the file to specify the network prefix.

[root@server1 ~]# echo "PREFIX1=24" >> /etc/sysconfig/network-scripts/ifcfg-eth0
[root@server1 ~]# echo "PREFIX2=24" >> /etc/sysconfig/network-scripts/ifcfg-eth0

Reload the configuration changes.
```
[root@server1 ~]# nmcli con reload
```

Restart the connection with the new settings.

[root@server1 ~]# nmcli con up "System eth0"

Look at new ifcfg-eth0 file and make sure network configuration changes took place:

[root@server1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
[root@server1 ~]# ip addr show dev eth0

Log in to desktop1.example.com and attempt to ping 192.168.201.
```
[root@desktop1 ~]# ping 192.168.0.201
```
From the desktop1.example.com system, reset the server1.example.com host to default settings:
```
[root@desktop1 ~]# lab-resetvm
```

4. Configure Host Names and Name Resolution

In this lab, you configure the system host name and name resolution.

Display the current host name.

[root@server1 ~]# hostname
server1.example.com

Display the host name status.

[root@server1 ~]# hostnamectl status
   Static hostname:server1.example.com
         Icon name:computer
           Chassis:n/a
        Machine ID:9f6fb63045a845d79e5e870b914c61c9
           Boot ID:d4ec3a2e8d3c48749aa82738c0ea946a
  Operating System:Red Hat Enterprise Linux Server 7.0 (Maipo)
       CPE OS Name:cpe:/o:redhat:enterprise_linux:7.0:beta:server
            Kernel:Linux 3.10.0-97.el7.x86_64
      Architecture:x86_64

Temporarily change the host name.
```
[root@server1 ~]# hostname testname
```
Display the current host name.
```
[root@server1 ~]# hostname
testname
```
View the configuration file providing the host name at network start.
```
[root@server1 ~]# cat /etc/hostname
server1.example.com
```
Reboot the system.
```
[root@server1 ~]# reboot
```

Display the current host name.

[root@server1 ~]# hostname
server1.example.com

Set hostname to survive reboots:

[root@server1 ~]# hostnamectl set-hostname testname.foo
[root@server1 ~]# cat /etc/hostname

Add a local nickname for the instructor server.

Look up the IP address of instructor.example.com.

[root@server1 ~]# host instructor.example.com
instructor.example.com has address 192.168.0.254

Modify /etc/hosts so that the name class has the IP address 192.168.0.254 and can be used to communicate with instructor.example.com.

[root@server1 ~]# vim /etc/hosts
[root@server1 ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.0.254 instructor.example.com class
192.168.0.254 content.example.com

Look up the IP address of class.

[root@server1 ~]# host class
Host class not found:2(SERVFAIL)
[root@server1 ~]# getent hosts class
192.168.0.254    instructor.example.com class

Ping class.

[root@server1 ~]# ping -c3 class
PING instructor.example.com (192.168.0.254) 56(84) bytes of data.
64 bytes from instructor.example.com (192.168.0.254):icmp_seq=1 ttl=64 time=0.397 ms
64 bytes from instructor.example.com (192.168.0.254):icmp_seq=2 ttl=64 time=0.447 ms
64 bytes from instructor.example.com (192.168.0.254):icmp_seq=3 ttl=64 time=0.470 ms

--- instructor.example.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.397/0.438/0.470/0.030 ms

Reset server1.example.com back to default settings.
```
[root@server1 ~]# lab-resetvm
```