Linux network tool

Posted on |

Linux network commands

ip

ip command is used to edit and display the configuration of network interfaces, routing, and tunnels. On many Linux systems, it replaces the deprecated ifconfig command.

1
2
3
4
5
6
7
8
9
ip link  del docker0   # delete a virtual network interface 
ip addr add 192.168.0.1  dev eth1  #assign IP to a specific interface(eht1)
ip addr show #check network interface 
ip addr del 192.168.0.1 dev eth1 
ip link set eth1 up/down
ip route [show] 
ip route add 192.168.0.1 via 10.10.20.0 dev eth0  #add static route 192.168.0.1
ip route del 192.168.0.1  #remove static route
ip route add default via 192.168.0.1 # add default gw

netstate

netstate used to display active sockets/ports for each protocol (tcp/ip)

1
2
netstat -lat 
netstat -us

nmcli

nmcli is a Gnome command tool to control NetworkManager and report network status: 

1
2
nmcli  device status 
nmcli connection show =

route

route

1
2
3
4
route  ==>  ip route (modern version) ##print router 
route add -net sample-net gw 192.168.0.1 
route del -net link-local netmask  255.255.0.0  #delete a virtual network interface 
ip route flush  # flashing routing table

tracepath

tracepath is used to traces path to a network host discovering MTU along this path. a modern version is traceroute.

1
2
3
4
tracepath 192.168.0.1 
``` 
### networking service

systemctl restart networking
/etc/init.d/networking restart

or

service NetworkManager stop

1
2
3
4
5
6
7
8
9
## network interface 
location at `/etc/network/interfaces` 
`eno1` is onboard Ethernet(wired) adapter. if machines has already `eth1` in its config file, for the second adapter, it will use `eno1` rather than using `eth2`.
[ifconfig](https://www.ibm.com/support/knowledgecenter/ssw_aix_71/i_commands/ifconfig.html) is used to set up network interfaces such as Loopback, Ethernet network interface: a software interface to networking hardware, e.g.  physical or virtual. physical interface, such as `eth0`, namely Ethernet network card. virtual interface such as `Loopback`, `bridges`, `VLANs` e.t.c.

ifconfig -a
ifconfig eth0 #check specific network interface
ifconfig eth0 192.168.0.1 #assign static IP address to network interface
ifconfig eth0 netmask 255.255.0.0 #assign netmask

ifconfig docker0 down/up 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
replaced by `ip` command later.
### why enp4s0f2 instead of eth0
[change back to eth0](https://www.itzgeek.com/how-tos/mini-howtos/change-default-network-name-ens33-to-old-eth0-on-ubuntu-16-04.html)
```shell
lspci | grep -i "net"
dmesg | grep -i eth0
ip a 
sudo vi /etc/default/grub
	GRUB_CMDLINELINUX="net.ifnames=0 biosdevname=0"
update-grub
# update  /etc/network/interfaces 
auto eth0
iface eth0  inet static 
sudo reboot

Unknown interface enp4s0f2

due TO /etc/network/interfaces has auto enp4s0f2 line, which always create this network interface , when restart the networking service.

ping hostname with docker0

usually there may be have multi network interfaces(eth0, docker0, bridge..) on a remote host, when ping this remote host with exisiting docker network (docker0), by default will talk to the docker0, which may not the desired one.

build LAN cluster with office PCs

  • setup PC IPs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
master node: 
IP Address:  192.168.0.1 
netmask: 24
Gateway: null
DNS serer:  10.3.101.101 
worker node:
IP address:  192.168.0.12
netmask: 24
Gateway: 192.168.0.1
DNS: 10.255.18.3
``` 
* `ufw disable` 
*  update `/etc/hosts` file:
192.168.0.1 master
192.168.0.12 worker 

if need to update the default hostname to `worker`, can modify `/etc/hostname` file, and reboot.

* ping test :

```script 

ping -c 3 master 
ping -c 3 worker
  • set ssh access(optionally)

sudo apt-get install openssh-server 
ssh-keygen -t rsa 
# use custmized key
cp rsa_pub.key authorized_key

refer

Ubuntu add static route

10 useful IP commands