Explore information related to ip address

dhclient to persistently look for an IP address lease - Configure it Now

This article covers how to use dhclient command. Basically, Linux dhclient command can provide an IP lease until DHCP Server/Router grants one.

With this guide, you can easily configure Linux dhclient command to continuously requests an IP lease until one is granted by DHCP Server / Router.

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Force DHCP Client to Renew IP Address - Perform it now

This article covers how to force DHCP client to renew IP address. You need to use Dynamic Host Configuration Protocol Client i.e., dhclient command. 

The client normally doesn't release the current lease as it is not required by the DHCP protocol. Some cable ISPs require their clients to notify the server if they wish to release an assigned IP address. 

The dhclient command, provides a means for configuring one or more network interfaces using the Dynamic Host Configuration Protocol, BOOTP protocol, or if these protocols fail, by statically assigning an address.


Linux renew ip command using dhcp:

The -r flag explicitly releases the current lease, and once the lease has been released, the client exits. 

For example, open terminal application and type the command:

$ sudo dhclient -r

Now obtain fresh IP address using DHCP on Linux:

$ sudo dhclient


To start DHCP client in Linux:

1. To start the DHCP service, type the following command: # /etc/init.d/dhcp start.

2. To stop the DHCP service, type the following command: # /etc/init.d/dhcp stop. 

The DHCP daemon stops until it is manually started again, or the system reboots.


How can I renew or release an IP in Linux for eth0?

To renew or release an IP address for the eth0 interface, enter:

$ sudo dhclient -r eth0

$ sudo dhclient eth0

In this example, I am renewing an IP address for my wireless interface:

sudo dhclient -v -r eth0

sudo dhclient -v eth0


Command to release/renew a DHCP IP address in Linux:

1. ip a - Get ip address and interface information on Linux

2. ip a s eth0 - Find the current ip address for the eth0 interface in Linux

3. dhclient -v -r eth0 - Force Linux to renew IP address using a DHCP for eth0 interface

4. systemctl restart network.service - Restart networking service and obtain a new IP address via DHCP on Ubuntu/Debian Linux

5. systemctl restart networking.service - Restart networking service and obtain a new IP address via DHCP on a CentOS/RHEL/Fedora Linux

6. nmcli con - Use NetworkManager to obtain info about Linux IP address and interfaces

7. nmcli con down id 'enp6s0' - Take down Linux interface enp6s0 and release IP address in Linux

8. nmcli con up id 'enp6s0' - Obtian a new IP address for Linux interface enp6s0 and release IP address using DHCP

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Use Nmap to Scan Open Ports - How to

This article covers how to use Nmap to Scan Open Ports. Nmap is the world's leading port security network scanner. The Nmap hosted security tool can help you determine how well your firewall and security configuration is working.

How would you tell Nmap to scan all ports?
By default, Nmap scans the 1,000 most popular ports of each protocol it is asked to scan.
Alternatively, you can specify the -F (fast) option to scan only the 100 most common ports in each protocol or --top-ports to specify an arbitrary number of ports to scan.

The OS and Service scanning options are helpful for scanning a particular port or service to get more information.
If a service is running on a non-default port, it might be by design – or it might suggest there is a security breach.
Ports often have a default usage. Most ports under 1000 are dedicated and assigned to a specific service.

What file does Nmap use to determine which ports to scan?
Nmap needs an nmap-services file with frequency information in order to know which ports are the most common.

Malicious ("black hat") hackers (or crackers) commonly use port scanning software to find which ports are "open" (unfiltered) in a given computer, and whether or not an actual service is listening on that port. They can then attempt to exploit potential vulnerabilities in any services they find.

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IMAP server wants to alert you to the following error

This article will guide you the different causes for the error 'your IMAP server wants to alert you to the following'.

IMAP #Error code #0x800cccdd appears alongside the message "Your IMAP server closed the connection", which signifies that the "Send/Receive" feature—a setting that retrieves your #Outlook mail whenever connected to the Internet in order to keep your mail synced—has failed.

The error message "Your account temporarily blocked for #IMAP use. This may be happen if you exceed the maximum number of simultaneous IMAP connections allowed. Kindly try after some time" occurs when the mail client or different mail clients are trying to establish too many connections to IMAP server.

A server connection timeout means that a server is taking too long to reply to a data request made from another device. Timeouts are not a reply message: they show up when there isn't a reply and a server request is not fulfilled in a predetermined length of time.

To fix the mail server is not responding:

1. Check your internet connection.

2. Check your #SMTP server details.

3. Verify all usernames and passwords.

4. Check your SMTP server connection.

5. Change your SMTP port.

6. Control your #antivirus or #firewall settings.

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Troubleshooting DHCP client issues

This article will guide you on troubleshooting different DHCP #client issues. Whenever a DHCP server gets a request from a client it responds with a DHCP offer containing IP address being offered, #network mask offered, the amount of time that the client can use and keep it, the ip address of the DHCP server making this offer.

To #Troubleshoot DHCP:

1. Check for IP Address Conflicts. #DHCP clients connect to the network using a leased IP address.

2. Check Physical Connectivity.

3. Test connections with other Client using a Static #IP Address.

4. Confirm Switch #Port #Configuration.

5. Verify the source of Clients IP Address.

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ifconfig centos 7

This article will guide you on the steps to #install #ifconfig in #CentOS using the yum #package #manager.

The ifconfig command can tell you a lot about your Unix server's connection to your #network and the role it's playing in both generating and receiving network traffic.

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Restrict anonymous login and ban IP address of attacker Windows

This article will guide you on the steps to Restrict anonymous login and ban #IP address of attacker by using Local Group Policy Editor in #Windows which allows us to prevent anonymous login and #IPBan helps to ban IP of #attacker. 

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Configuring Static IP and Hostname in FreeBSD 12 Steps to take

This article will guide you on how to configure network settings in FreeBSD by setting static IP addresses and DHCP addresses.

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phpIPAM installation on CentOS

This article will guide you on how to install phpIPAM on CentOS 8.

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