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Linux - Networking: Package `net-tools` (deprecated)

Linux - Networking: Package net-tools (deprecated)

Package `net-tools`

Package

sudo yum install net-tools
rpm -aq | grep net-tools

`ifconfig` Utility

ifconfig
- Stands for (interface configuration)
- used to configure, control, and display information about network interfaces.
- replaced by the ip command from the iproute suite.
Device

CMD	DESC
`ifconfig`	Display includes active network interfaces.
`ifconfig -a`	Display only active interfaces.
`ifconfig devce_id`	Display a specific network interface.
`ifconfig devce_id up`	Activates a specific network interface.
`ifconfig devce_id down`	Deactivates a specific network interface.

Runtime Configure

CMD	DESC
`ifconfig eth0 192.168.1.100 netmask 255.255.255.0`	Assigns an IP address for a specific interface.
`ifconfig eth0 broadcast 192.168.1.255`	Assigns a broadcast address to an interface.
`ifconfig devce_id hw ether new_MAC_address`	Change a new MAC address to a network interface.

`ifconfig`: Interface Info

ifconfig
# ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
#         inet 192.168.204.153  netmask 255.255.255.0  broadcast 192.168.204.255
#         inet6 fe80::20c:29ff:fe5b:ce78  prefixlen 64  scopeid 0x20<link>
#         ether 00:0c:29:5b:ce:78  txqueuelen 1000  (Ethernet)
#         RX packets 166189  bytes 241795084 (230.5 MiB)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 13913  bytes 2465843 (2.3 MiB)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
#         inet 127.0.0.1  netmask 255.0.0.0
#         inet6 ::1  prefixlen 128  scopeid 0x10<host>
#         loop  txqueuelen 1000  (Local Loopback)
#         RX packets 0  bytes 0 (0.0 B)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 0  bytes 0 (0.0 B)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
#         inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
#         ether 52:54:00:c5:c9:4d  txqueuelen 1000  (Ethernet)
#         RX packets 0  bytes 0 (0.0 B)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 0  bytes 0 (0.0 B)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Interface Name:
- the name of a physical or virtual network interface.
- ens160
Flags: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>
- UP: The interface is enabled.
- BROADCAST: The interface supports broadcasting.
- RUNNING: The interface is operational.
- MULTICAST: The interface supports multicast.
MTU (Maximum Transmission Unit):
- mtu 1500: the maximum size of packets (in bytes) that can be transmitted without fragmentation.
IPv4 Address Details:
- inet: 192.168.204.153: the IPv4 address assigned to the interface.
- netmask: 255.255.255.0: the subnet mask.
- broadcast: 192.168.204.255: the broadcast address.
IPv6 Address Details:
- inet6: fe80::20c:29ff:fe5b:ce78: the link-local IPv6 address.
- prefixlen 64: Specifies the subnet mask for IPv6.
- scopeid: Indicates the scope of the address (<link> means it’s local to the link).
MAC Address:
- ether 00:0c:29:5b:ce:78: the Media Access Control (MAC) address of the interface.
Transmit Queue Length
- txqueuelen 1000 (Ethernet): 1000 packets can be queued in the kernel for transmission before they are sent to the network hardware.
- interface type is Ethernet
Statistics:
- RX packets 166189: The number of packets received.
- RX bytes 241795084 (230.5 MiB): Total data received.
- RX errors, dropped, overruns, frame: All error counts for received packets are 0.
- TX packets 13913: The number of packets transmitted.
- TX bytes 2465843 (2.3 MiB): Total data transmitted.
- TX errors, dropped, overruns, carrier, collisions: All error counts for transmitted packets are 0.

Loopback Interface
- loopback interface used for communication within the local machine.
- name: lo
Flags: flags=73<UP,LOOPBACK,RUNNING>
- UP: The interface is enabled.
- LOOPBACK: Indicates it is a loopback interface.
- RUNNING: The interface is operational.
MTU (Maximum Transmission Unit):
- mtu 65536 allows larger packet sizes since it does not involve physical hardware.

Bridge Interface
- Interface Name: virbr0
- a virtual bridge interface used for virtual machines or containers.
Flags: flags=4099<UP,BROADCAST,MULTICAST>
- UP: The interface is enabled.
- BROADCAST: Supports broadcasting.
- MULTICAST: Supports multicast.
MTU (Maximum Transmission Unit):
- mtu 1500: specifies the maximum packet size.

Lab: Activate/Deactivate an Interface

# List all interfaces
ifconfig

# Get interface info
ifconfig ens224
# ens224: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
#         inet 192.168.204.170  netmask 255.255.255.0  broadcast 0.0.0.0
#         inet6 fe80::70eb:5c8e:a06e:f8e2  prefixlen 64  scopeid 0x20<link>
#         ether 00:0c:29:5b:ce:82  txqueuelen 1000  (Ethernet)
#         RX packets 2829  bytes 316014 (308.6 KiB)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 521  bytes 71586 (69.9 KiB)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# Deactivate an interface
ifconfig ens224 down
# verify
ifconfig ens224
# ens224: flags=4098<BROADCAST,MULTICAST>  mtu 1500
#         ether 00:0c:29:5b:ce:82  txqueuelen 1000  (Ethernet)
#         RX packets 2927  bytes 325316 (317.6 KiB)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 544  bytes 74548 (72.8 KiB)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# Activate an interface
ifconfig ens224 up
# verify
ifconfig ens224
# ens224: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
#         inet 192.168.204.171  netmask 255.255.255.0  broadcast 192.168.204.255
#         inet6 fe80::70eb:5c8e:a06e:f8e2  prefixlen 64  scopeid 0x20<link>
#         ether 00:0c:29:5b:ce:82  txqueuelen 1000  (Ethernet)
#         RX packets 0  bytes 0 (0.0 B)
#         RX errors 0  dropped 0  overruns 0  frame 0
#         TX packets 10  bytes 1454 (1.4 KiB)
#         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Lab: Assign a Static Runtime IP

# rename an inerface
ifconfig ens224 | grep "inet "
# inet 192.168.204.171  netmask 255.255.255.0  broadcast 192.168.204.255

# shutdown an interface device
ifconfig ens224 down

# assign a static IP
ifconfig ens224 192.168.204.100
ifconfig ens224 netmask 255.255.255.0

# Activate the interface device
ifconfig ens224 up

# verify
ifconfig ens224 | grep "inet "
# inet 192.168.204.100  netmask 255.255.255.0  broadcast 192.168.204.255

Reboot system and check ip

systemctl reboot

ifconfig ens224 | grep "inet "
# inet 192.168.204.171  netmask 255.255.255.0  broadcast 192.168.204.255

`route` Utility

route command
- used to view and manipulate the kernel’s IP routing table
- deprecated and has been replaced by the ip route command
Route Table

CMD	DESC
`route`	Display IP routing table
`route -n`	Display numerical addresses
`route add default gw 192.168.0.1`	Add a Default Route
`route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.1`	Add a static route to a specific network
`route change -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.2`	Change a Route
`route del -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.1`	Delete a Route

Lab: Displays IP Routing Table

route -n
# Kernel IP routing table
# Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
# 0.0.0.0         192.168.204.2   0.0.0.0         UG    100    0        0 ens160
# 0.0.0.0         192.168.204.2   0.0.0.0         UG    101    0        0 ens224
# 192.168.204.0   0.0.0.0         255.255.255.0   U     100    0        0 ens160
# 192.168.204.0   0.0.0.0         255.255.255.0   U     101    0        0 ens224

Columns:
- Destination:
  - Specifies the destination network or host.
  - 0.0.0.0:
    - Indicates the default route for all traffic not matching any specific destination.
  - 192.168.204.0: The
    - local subnet.
- Gateway:
  - The next-hop gateway for the route.
  - 192.168.204.2: Indicates that traffic destined for the listed Destination will be sent via this gateway.
  - 0.0.0.0: Indicates that the destination is directly reachable (no gateway is required).
- Genmask:
  - The subnet mask for the destination.
  - 0.0.0.0: Applies to all IP addresses (used for the default route).
  - 255.255.255.0: Applies to the subnet range 192.168.204.1–192.168.204.254.
- Flags:
  - Indicates the route’s properties.
  - U: The route is up (usable).
  - G: The route uses a gateway.
- Metric:
  - The cost of using this route.
  - Lower values are preferred when multiple routes exist.
  - 100 and 101 are metrics for the respective routes.
- Ref:
  - Unused in modern Linux systems (legacy field).
- Use:
  - Shows the count of lookups for this route (generally 0 for a new table).
- Iface:
  - The network interface associated with the route.
  - ens160 and ens224 are the interfaces for these routes.

`netstat` Utility

netstat command
- a network utility used to display active network connections, listening ports, routing tables, interface statistics, and other network-related information.
largely replaced by the ss command in newer Linux distributions

CMD	DESC
`netstat`	Display Active Network Connections
`netstat -t`	Display TCP Connections
`netstat -u`	Display UDP Connections
`netstat -l`	Display Listening Ports
`netstat -p`	Display Connections with Process Information
`netstat -tunlp`	Display Listening and Established Connections
`netstat -i`	Display Network Statistics
`netstat -r`	Display Routing Table
`netstat -rnv`	Display IP routing table

Lab: Displays IP Routing Table

netstat -rnv
# Kernel IP routing table
# Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
# 0.0.0.0         192.168.204.2   0.0.0.0         UG        0 0          0 ens160
# 0.0.0.0         192.168.204.2   0.0.0.0         UG        0 0          0 ens224
# 192.168.204.0   0.0.0.0         255.255.255.0   U         0 0          0 ens160
# 192.168.204.0   0.0.0.0         255.255.255.0   U         0 0          0 ens224

Kernel IP Routing Table
- shows how the system routes IP packets.
- Each row corresponds to a route in the routing table.
Columns:
- Destination:
  - The destination network or host to which packets are routed.
- Gateway:
  - The gateway (next-hop router) to reach the destination.
  - 0.0.0.0:
    - no gateway is needed;
    - the destination is directly reachable.
- Genmask:
  - The subnet mask applied to the destination to define the network’s size.
- Flags:
  - Indicates the route’s type.
  - Common flags:
    - U: The route is up (usable).
    - G: The route uses a gateway.
- MSS:
  - Maximum Segment Size for TCP connections over this route (0 means default).
- Window:
  - TCP window size (unused here).
- irtt:
  - Initial round-trip time (unused here, often 0).
- Iface:
  - The network interface used for the route.

Default Route:
- Destination:
  - 0.0.0.0
  - default route, meaning all traffic not matching any other route goes here.
- Gateway:
  - 192.168.204.2
  - next-hop router for traffic to non-local networks.
- Genmask:
  - 0.0.0.0
  - applies to all addresses.
- Flags: UG
  - Up and uses a Gateway.
- Iface:
  - ens160 and ens224
  - two interfaces are configured with the same default gateway.
Local Subnet:
- Destination:
  - 192.168.204.0
  - local subnet for this interface.
- Gateway:
  - 0.0.0.0
  - no gateway is needed, directly connected.
- Genmask:
  - 255.255.255.0
  - covers IPs from 192.168.204.1 to 192.168.204.254.
- Flags: U
  - Up, directly reachable.
- Iface:
  - ens160 and ens224
  - both interfaces are on the same subnet.

TOP

Note_Tech

Linux - Networking: Package net-tools (deprecated)

Package net-tools

ifconfig Utility

ifconfig: Interface Info

Lab: Activate/Deactivate an Interface

Lab: Assign a Static Runtime IP

route Utility

Lab: Displays IP Routing Table

netstat Utility

Lab: Displays IP Routing Table

Linux - Networking: Package `net-tools` (deprecated)

Package `net-tools`

`ifconfig` Utility

`ifconfig`: Interface Info

`route` Utility

`netstat` Utility