/var/log/messages HowTo - Linux / Unix Q & A from nixCraft

CentOS 7 Run Script When Network Interface is Up (Network Manager)

last updated October 15, 2018 in CentOS, Linux, Networking, RedHat and Friends

I want to run a shell script or other program immediately after my network interface goes up on a CentOS 7 / RHEL 7 server. I created /sbin/ifup-local, but it is not working on a CentOS 7 box but works perfectly on CentOS 6. I am using NetworkManager with CentOS 7. How do I run ifup-post or ifup-pre scripts?

Linux Command To Find SATA Link Speed Such as 1.5 / 3.0 / 6.0 Gbps [ Hard Disk ]

last updated October 1, 2018 in Hardware, Linux, Troubleshooting

How do I find out my SATA link speed? How do I make sure my sata hard disk is working at 6Gbps speed and how do I verify this on a Linux server running on HP or IBM amd64 hardware?

Linux: Neighbour Table Overflow Error and Solution

last updated December 19, 2011 in CentOS, Linux, Troubleshooting

I setup a CentOS Linux based Linux server running as a gateway and firewall server. However, I’m getting the following messages in the /var/log/messages log file:

Dec 20 00:41:01 fw01 kernel: Neighbour table overflow.
Dec 20 00:41:01 fw01 last message repeated 20 times

Dec 20 00:41:01 fw03 kernel: [ 8987.821184] Neighbour table overflow.
Dec 20 00:41:01 fw03 kernel: [ 8987.860465] printk: 100 messages suppressed.

Why does kernel throw “Neighbour table overflow” messages in syslog? How do I fix this problem under Debian / CentOS / RHEL / Fedora / Ubuntu Linux?

Ubuntu Linux Set Iscsi Initiator

last updated July 2, 2010 in Ubuntu Linux

ISCSI is a network protocol standard that allows the use of the SCSI protocol over TCP/IP networks. How do I setup Iscsi Initiator under Ubuntu Linux? How do I format and connect to an iSCSI volume under Ubuntu Linux? How do I store VMware or Virtualbox virtual machine images using iscsi storage?

CentOS / Redhat Linux: Install Keepalived To Provide IP Failover For Web Cluster

last updated May 3, 2017 in CentOS, High Availability, KeepAlived, Linux, Nginx, RedHat and Friends, UNIX

Keepalived provides a strong and robust health checking for LVS clusters. It implements a framework of health checking on multiple layers for server failover, and VRRPv2 stack to handle director failover. How do I install and configure Keepalived for reverse proxy server such as nginx or lighttpd?

BIND: Max open files (1024) is smaller than max sockets (4096) Error and Solution

last updated May 1, 2009 in Bind dns, CentOS, Debian / Ubuntu, Networking, Package Management, RedHat and Friends, Troubleshooting

While going though my logs I found that BIND9 on Debian version 5.x is giving a warning which read as follows:

max open files (1024) is smaller than max sockets (4096)

How do I fix this problem?

BIND: Clocks are Unsynchronized Error and Solution

last updated February 1, 2009 in Bind dns, CentOS, Debian / Ubuntu, FreeBSD, HP-UX Unix, Linux, Networking, OpenBSD, Package Management, RedHat and Friends, Solaris-Unix, Suse, Troubleshooting, Ubuntu Linux, UNIX

Q. I’ve configured BIND named TSIG as documented here. It worked for some time, but my /var/log/messages got the errors as follows:

zone example.org/IN: refresh: failure trying master 71.22.11.22#53 (source 0.0.0.0#0): clocks are unsynchronized: 9 Time(s)
zone example.org/IN: refresh: failure trying master 71.22.11.22#53 (source 71.22.11.22#0): clocks are unsynchronized: 9 Time(s)

How do I fix these errors under Debian Linux 64 bit etch server?