CentOS 6 and 7 / RHEL Persistent DHCP Solution

It is very silly but the default on the ifup-eth script tells dhclient ( the program that obtains a DHCP IP address if you have selected DHCP in your ifcfg-eth* config file) to EXIT / QUIT if the first attempt to obtain a lease fails.

No amount of dhclient.conf settings will fix this because if dhclient is started with -1 (which it is by default) then dhclient will quit.

This is obviously very bad for MOST cases.  Say for example you have a power outage or you initially power on the system, if for some reason the link takes a few more seconds to come up, dhclient has probably already quit being unable to obtain a lease the first time.

So the option to set in your ifcfg-eth0 config file to solve the dhclient persistent issue:

PERSISTENT_DHCLIENT=1

The difference in how dhclient is started now looks like this:

/sbin/dhclient -H hostname -q -lf /var/lib/dhclient/dhclient-eth0.leases -pf /var/run/dhclient-eth0.pid eth0

If you don't have the option above you will see a "-1" which indicates that it would quit if the first lease attempt fails:

/sbin/dhclient -H hostname -1 -q -lf /var/lib/dhclient/dhclient-eth0.leases -pf /var/run/dhclient-eth0.pid eth0

 

If you are looking for the equivalent Debian/Ubuntu/Mint solution then check this dhclient solution.


Tags:

centos, rhel, persistent, dhcp, solutionit, default, ifup, eth, dhclient, obtains, ip, selected, ifcfg, config, obtain, lease, fails, conf, settings, outage, initially, unable, persistent_dhclient, sbin, hostname, lf, var, lib, leases, pf, pid, quot, indicates,

Latest Articles

  • Cisco CME How To Enable ACD hunt groups
  • How to install gns3 on Linux Ubuntu Mint
  • How to convert audio for Asterisk .wav format
  • Using Cisco CME Router with Asterisk as a dial-peer
  • Cisco CME How To Configure SIP Trunk VOIP
  • Virtualbox host Only Network Error Failed to save host network interface parameter - Cannot change gateway IP of host only network
  • Cisco CME and C7200 Router Testing and Learning Environment on Ubuntu 20+ Setup Tutorial Guide
  • Abusive IP ranges blacklist
  • How to Install Any OS on a Physical Drive from Windows Using VMware Workstation (Linux, Windows, BSD)
  • CDN Cloudflare how to set and preserve the real IP of the client without modifying application code on Apache
  • CentOS 7 fix Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=container error was 14: curl#6 -
  • Ubuntu Debian How To Install Recommended Packages Automatically
  • How to set Linux Ubuntu Redhat Debian Command Line http https socks proxy for yum apt
  • How to resize a pdf without losing much quality in Linux Mint Ubuntu Debian Redhat Solution
  • qemu: could not load PC BIOS 'bios-256k.bin' solution
  • Proxmox How To Custom Partition During Install
  • Hyper-V Linux VM Boots to Black Screen, Storage, NIC Not Found Issues
  • Ubuntu Mint How to Fix Missing/Broken /dev and /dev/pts which causes terminal to immediately close exit and not work
  • How high can a Xeon CPU get?
  • bash fix PATH environment variable "command not found" solution