Network Flashcards
lists all available network interfaces on your system
ip link show
view device and address info of device ens3
ip addr show ens3
show statistics about a specific network dev performance
ip -s link show ens3
tests connectivity to a machine
ping -c3 192.0.2.254
ping6 2001:db8:0:1::1
find other IPv6 nodes on the local network
ping6 ff02::1%ens4
show routing information
ip route
ip -6 route
trace the network traffic path to reach a remote host
tracepath access.redhat.com
mtr access.redhat.com
display socket statistics.
ss -ta
ss -plunt
Locate the network interface name that is associated with the 52:54:00:00:fa:0a Ethernet address
ip link
Display the current IP address and netmask for all interfaces
ip -br addr
Display the statistics for the enX interface.
ip -s link show enX
Display the listening TCP sockets on the local system
ss -lt
displays the status of all network devices
nmcli dev status
displays a list of all connections.
nmcli con show
displays a list of all active connections.
nmcli con show --active
adds an eno2 connection of the ethernet type for the eno2 network interface
nmcli con add con-name eno2 type ethernet ifname eno2
creates an eno3 connection of the ethernet type for the eno3 network interface with a static IPv4 network setting
nmcli con add con-name eno3 type ethernet ifname eno3 ipv4.method manual ipv4.addresses 192.168.0.5/24 ipv4.gateway 192.168.0.254
activates a network connection on the device that it is bound to
nmcli con up static-ens3
disconnects the network device and brings down the connection
nmcli dev disconnect ens3
list the current settings for a connection
nmcli con show static-ens3
update the static-ens3 connection to set the 192.0.2.2/24 IPv4 address and the 192.0.2.254 default gateway. automatically enable the connection at system boot.
nmcli con mod static-ens3 ipv4.addresses 192.0.2.2/24 ipv4.gateway 192.0.2.254 connection.autoconnect yes
update the static-ens3 connection to set the 2001:db8:0:1::a00:1/64 IPv6 address and the 2001:db8:0:1::1 default gateway
nmcli con mod static-ens3 ipv6.addresses 2001:db8:0:1::a00:1/64 ipv6.gateway 2001:db8:0:1::1
adds the 2.2.2.2 DNS server to the static-ens3 connection
nmcli con mod static-ens3 +ipv4.dns 2.2.2.2
loads all connection profiles
nmcli con reload
loads only the eno2 connection profile
nmcli con reload en02
deletes a connection from the system
nmcli con del static-ens3
view your current permissions
nmcli gen permissions
useful network manager commands
nmcli dev status
nmcli dev disconnect
nmcli con show
nmcli con up
nmcli con reload
nmclicon edit
nmcli con mod
nmcli con add
nmcli con del
NetworkManager config file format
ini
Connection properties
ip4.address1
ip4.method
ip4.gateway
ip4.dns
ip4.dns-search
ip4.ignore-auto-dns
connection.autoconnect
connection.id
connection.interface-name
connection.type
connection.uuid
802-3-ethernet.mac-address
What do you do after changing a connection config file?
nmcli con reload
nmcli con up static-ens3
Determine hostname
hostname
Where is hostname stored
/etc/hostname
Set hostname via cli
hostnamectl hostname example.com
How does stub resolver go about converting names to ips?
determines where to look based on /etc/nsswitch.conf . By default it uses /etc/hosts
Command to test hostname resolution
getent hosts hostname
Explain the content of /etc/resolv.conf
nameserver: up to 3 nameservers
search: suffixes to append to requests when querying just a hostname
domain: hostname resolution in a local network
Change dns with nmcli
nmcli con mod ID ipv4.dns IP
nmcli con down ID
nmcli con up ID
adds or removes an individual dns entry
nmcli con mod ID +ipv4.dns IP
test DNS server connectivity
dig example.com
host example.com
test DNS server connectivity specifically usin /etc/hosts
getent hosts example.com
