Red Hat System Administration I

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Guided Exercise: Validate Network Configuration

In this exercise, you inspect the network configuration of one of your servers.

Outcomes

  • Identify the current network interfaces and network addresses.

As the student user on the workstation machine, use the lab command to prepare your system for this exercise.

This command prepares your environment and ensures that all required resources are available.

[student@workstation ~]$ lab start net-validate

Instructions

  1. Use the ssh command to log in to servera as the student user. The systems are configured to use SSH keys for authentication and passwordless access to servera.

    [student@workstation ~]$ ssh student@servera
...output omitted...
[student@servera ~]$

  2. Locate the network interface name that is associated with the 52:54:00:00:fa:0a Ethernet address. Record or remember this name and use it to replace the enX placeholder in subsequent commands.

    Important

    Network interface names are determined by their bus type and the detection order of devices during boot. Your network interface names vary according to the course platform and hardware in use.

    On your system, locate the interface name (such as ens06 or en1p2) that is associated with the 52:54:00:00:fa:0a Ethernet address. Use this interface name to replace the enX placeholder that is used throughout this exercise.

    [student@servera ~]$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enX: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:00:fa:0a brd ff:ff:ff:ff:ff:ff

  3. Display the current IP address and netmask for all interfaces.

    [student@servera ~]$ ip -br addr
lo          UP          127.0.0.1/8 ::1/128
enX:        UP          172.25.250.10/24 fe80::3059:5462:198:58b2/64

  4. Display the statistics for the enX interface.

    [student@servera ~]$ ip -s link show enX
2: enX: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 52:54:00:00:fa:0a brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast
    89014225   168251   0       154418  0       0
    TX: bytes  packets  errors  dropped carrier collsns
    608808     6090     0       0       0       0

  5. Display the route information.

    [student@servera ~]$ ip route
default via 172.25.250.254 dev enX proto static metric 100
172.25.250.0/24 dev enX proto kernel scope link src 172.25.250.10 metric 100

  6. Verify that the router is accessible.

    [student@servera ~]$ ping -c3 172.25.250.254
PING 172.25.250.254 (172.25.250.254) 56(84) bytes of data.
64 bytes from 172.25.250.254: icmp_seq=1 ttl=64 time=0.196 ms
64 bytes from 172.25.250.254: icmp_seq=2 ttl=64 time=0.436 ms
64 bytes from 172.25.250.254: icmp_seq=3 ttl=64 time=0.361 ms

--- 172.25.250.254 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 49ms
rtt min/avg/max/mdev = 0.196/0.331/0.436/0.100 ms

  7. Show all the hops between the local system and the classroom.example.com system.

    [student@servera ~]$ tracepath classroom.example.com
 1?: [LOCALHOST]                      pmtu 1500
 1:  bastion.lab.example.com                               0.337ms
 1:  bastion.lab.example.com                               0.122ms
 2:  172.25.254.254                                        0.602ms reached
     Resume: pmtu 1500 hops 2 back 2

  8. Display the listening TCP sockets on the local system.

    [student@servera ~]$ ss -lt
State      Recv-Q Send-Q      Local Address:Port         Peer Address:Port
LISTEN     0      128               0.0.0.0:sunrpc            0.0.0.0:*
LISTEN     0      128               0.0.0.0:ssh               0.0.0.0:*
LISTEN     0      128                  [::]:sunrpc               [::]:*
LISTEN     0      128                  [::]:ssh                  [::]:*

  9. Return to the workstation system as the student user.

    [student@servera ~]$ exit
logout
Connection to servera closed.
[student@workstation ~]$

Finish

On the workstation machine, change to the student user home directory and use the lab command to complete this exercise. This step is important to ensure that resources from previous exercises do not impact upcoming exercises.

[student@workstation ~]$ lab finish net-validate

This concludes the section.

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