How to Change Linux IP address

Q. How do I change ip address in Linux?

A. There are different ways to change IP address in Linux

(a) Command Line tools
(b) Modify configuration files
(c) Use GUI tools

Task: Display current IP address and setting for network interface called eth0

Use ifconfig command:

# ifconfig eth0

Output:

eth0      Link encap:Ethernet  HWaddr 00:30:48:5A:BF:46
inet addr:10.5.123.2  Bcast:10.5.123.63  Mask:255.255.255.192
          inet6 addr: fe80::230:48ff:fe5a:bf46/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:728204 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1097451 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:62774749 (59.8 MiB)  TX bytes:1584343634 (1.4 GiB)
          Interrupt:177

Task: Change IP address 

 

You can change ip address using ifconfig command itself. To set IP address
192.168.1.5, enter command:

# ifconfig eth0 192.168.1.5 netmask 255.255.255.0 up

# ifconfig eth0


To make permanent changes to IP address you need to edit configuration file according to your Linux distribution.

How to Change Linux IP address

Q. How do I change ip address in Linux?

A. There are different ways to change IP address in Linux

(a) Command Line tools
(b) Modify configuration files
(c) Use GUI tools

Task: Display current IP address and setting for network interface called eth0

Use ifconfig command:

# ifconfig eth0

Output:

eth0      Link encap:Ethernet  HWaddr 00:30:48:5A:BF:46
inet addr:10.5.123.2  Bcast:10.5.123.63  Mask:255.255.255.192
          inet6 addr: fe80::230:48ff:fe5a:bf46/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:728204 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1097451 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:62774749 (59.8 MiB)  TX bytes:1584343634 (1.4 GiB)
          Interrupt:177

Task: Change IP address 

 

You can change ip address using ifconfig command itself. To set IP address
192.168.1.5, enter command:

# ifconfig eth0 192.168.1.5 netmask 255.255.255.0 up

# ifconfig eth0


To make permanent changes to IP address you need to edit configuration file according to your Linux distribution.

Linux change IP address

Q. How do I change ip address in Linux?

A. There are different ways to change IP address in Linux

(a) Command Line tools
(b) Modify configuration files
(c) Use GUI tools

Task: Display current IP address and setting for network interface called eth0

Use ifconfig command:

# ifconfig eth0

Output:

eth0      Link encap:Ethernet  HWaddr 00:30:48:5A:BF:46
          inet addr:10.5.123.2  Bcast:10.5.123.63  Mask:255.255.255.192
          inet6 addr: fe80::230:48ff:fe5a:bf46/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:728204 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1097451 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:62774749 (59.8 MiB)  TX bytes:1584343634 (1.4 GiB)
          Interrupt:177

Task: Change IP address 

 

You can change ip address using ifconfig command itself. To set IP address
192.168.1.5, enter command:

# ifconfig eth0 192.168.1.5 netmask 255.255.255.0 up

# ifconfig eth0


To make permanent changes to IP address you need to edit configuration file according to your Linux distribution.

check banned ip address in Linux

 

 

How do I find or check IP's that are currently banned using iptables command in Linux? How do I verify that IP address 1.2.3.4 is banned or not in Linux?

The correct syntax to block an IP address under Linux using iptables is as follows:

 
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS -j DROP
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS/MASK -j DROP

Open a command-line terminal (select Applications > Accessories > Terminal), or login to remote server using the ssh and then type the following command block an ip address 1.2.3.4 as follows:

# /sbin/iptables -A INPUT -s 65.55.44.100 -j DROP

To view blocked IP address, enter:

# iptables -L INPUT -v -n

OR

# iptables -L INPUT -v -n | less

Task: Check Banned IP's Linux

Use the grep command as follows to verify that an IP address 1.2.3.4 is blocked or not:

# iptables -L INPUT -v -n | grep "1.2.3.4"

How Do I Delete or Unblock IP Address 1.2.3.4?

Use the following syntax to delete or unblock an IP address under Linux, enter:

# iptables -D INPUT -s 1.2.3.4 -j DROP

Finally, make sure you save the firewall:

# service iptables save

check banned ip address in Linux

 

 

How do I find or check IP's that are currently banned using iptables command in Linux? How do I verify that IP address 1.2.3.4 is banned or not in Linux?

The correct syntax to block an IP address under Linux using iptables is as follows:

 
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS -j DROP
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS/MASK -j DROP

Open a command-line terminal (select Applications > Accessories > Terminal), or login to remote server using the ssh and then type the following command block an ip address 1.2.3.4 as follows:

# /sbin/iptables -A INPUT -s 65.55.44.100 -j DROP

To view blocked IP address, enter:

# iptables -L INPUT -v -n

OR

# iptables -L INPUT -v -n | less

Task: Check Banned IP's Linux

Use the grep command as follows to verify that an IP address 1.2.3.4 is blocked or not:

# iptables -L INPUT -v -n | grep "1.2.3.4"

How Do I Delete or Unblock IP Address 1.2.3.4?

Use the following syntax to delete or unblock an IP address under Linux, enter:

# iptables -D INPUT -s 1.2.3.4 -j DROP

Finally, make sure you save the firewall:

# service iptables save

Iptables Find / Check Banned IP Address

Linux: Iptables Find / Check Banned IP Address

How do I find or check IP's that are currently banned using iptables command in Linux? How do I verify that IP address 1.2.3.4 is banned or not in Linux?

The correct syntax to block an IP address under Linux using iptables is as follows:

 
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS -j DROP
/sbin/iptables -A INPUT -s BAN-IP-ADDRESS/MASK -j DROP
 

Open a command-line terminal (select Applications > Accessories > Terminal), or login to remote server using the ssh and then type the following command block an ip address 1.2.3.4 as follows:

# /sbin/iptables -A INPUT -s 65.55.44.100 -j DROP

To view blocked IP address, enter:

# iptables -L INPUT -v -n

OR

# iptables -L INPUT -v -n | less

Task: Check Banned IP's Linux

Use the grep command as follows to verify that an IP address 1.2.3.4 is blocked or not:

# iptables -L INPUT -v -n | grep "1.2.3.4"

How Do I Delete or Unblock IP Address 1.2.3.4?

Use the following syntax to delete or unblock an IP address under Linux, enter:

# iptables -D INPUT -s 1.2.3.4 -j DROP

Finally, make sure you save the firewall:

# service iptables save

Linux Random Password Generator Command

How do I generate random passwords on the Linux command line using the bash shell?

You can use the following shell function to generate random password. Edit ~/.bashrc file, enter:
$ vi $HOME/.bashrc
Append the following code:

 
genpasswd() {
local l=$1
[ "$l" == "" ] && l=16
tr -dc A-Za-z0-9_ < /dev/urandom | head -c ${l} | xargs
}

Save and close the file. Source ~/.bashrc again, enter:
$ source ~/.bashrc
To generate random password, enter:
$ genpasswd
To generate 8 character long random password, enter:
$ genpasswd 8

Linux Random Password Generator Command

How do I generate random passwords on the Linux command line using the bash shell?

You can use the following shell function to generate random password. Edit ~/.bashrc file, enter:
$ vi $HOME/.bashrc
Append the following code:

 
genpasswd() {
local l=$1
[ "$l" == "" ] && l=16
tr -dc A-Za-z0-9_ < /dev/urandom | head -c ${l} | xargs
}

Save and close the file. Source ~/.bashrc again, enter:
$ source ~/.bashrc
To generate random password, enter:
$ genpasswd
To generate 8 character long random password, enter:
$ genpasswd 8

Linux Random Password Generator Command

How do I generate random passwords on the Linux command line using the bash shell?

You can use the following shell function to generate random password. Edit ~/.bashrc file, enter:
$ vi $HOME/.bashrc
Append the following code:

 
genpasswd() {
 local l=$1
        [ "$l" == "" ] && l=16
       tr -dc A-Za-z0-9_ < /dev/urandom | head -c ${l} | xargs
}
 

Save and close the file. Source ~/.bashrc again, enter:
$ source ~/.bashrc
To generate random password, enter:
$ genpasswd
To generate 8 character long random password, enter:
$ genpasswd 8