5-1 [Deploy, Configure and Maintain Systems] Configure Networking and Hostname Resolution Statically or Dynamically: Troubleshooting

Question 1

ip addr show eth0

Answer 1

Display IP information for a device

Question 2

ip -s link show eth0

inside output of
ip -s link show eth0

RX means sent
and TX is bytes received, which shows it is connected to some kind of network

2: eth0: mtu 9001 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 06:d7:d9:81:61:96 brd ff:ff:ff:ff:ff:ff
RX: bytes packets errors dropped overrun mcast
12798065 24964 0 0 0 0
TX: bytes packets errors dropped carrier collsns
4036735 17575 0 0 0 0

Answer 2

Display network statistics for a device

Question 3

ip route

Answer 3

Display routes for a device

Question 4

ip link

Answer 4

Display network devices

Question 5

tracepath

tracepath6

the pmtu size 1500
[root@abrarali1c ~]# tracepath yahoo.com
1?: [LOCALHOST] pmtu 9001
1: gateway 0.186ms pmtu 1500
1: no reply

Answer 5

Show all hops a packet has to go through and the MTA for each router

not all routers
support this require it to be enabled on the router

For ipv 6, Show all hops a packet has to go through and the MTA for each router

How to see maximum packet allowed through to an ip

Question 6

yum install traceroute
traceroute
traceroute6

Answer 6

older version command to trace and works on all routers

ipv 6 version of tracer that works on all routers

Question 7

ping yahoo.com

ping -c5 yahoo.com

ping6 yahoo.com

Answer 7

ping a ipv site till hit control c

ping a site 5 times and stop

ping a ipv 6 site

Question 8

ss

inside ss command
right side of third column for port
right side of fourth column for internal port mapping, not external ports/connections

older command:
netstat

Answer 8

utility used to look at listening ports, established connections, and investigate sockets

• a All, listening and established
• t Display TCP sockets
• n Show numbers instead of names and port number (ip address number with port number instead of ex: yahoo.com:smtp) for interfaces and ports
• u Display udp sockets
• l Show only listening sockets

Question 9

ss -tan, see if port 80 is there (likely not)
yum install httpd
systemctl httpd start
ss -tan, see if port 80 is there (should be there)
got to public ip on a browser
ss -tan, see if port 80 is there with an ip listening to it

Answer 9

use apache server to show port example in ss