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82
votes
9answers
93k views

When does `cron.daily` run?

When do entries in cron.daily (and .weekly and .hourly) run, and is it configurable? I haven't found a definitive answer to this, and am hoping there is one. I'm running RHEL5 and CentOS 4, but for ...
78
votes
5answers
147k views

What version of RHEL am I using?

From the shell and without root privileges, how can I determine what Red Hat Enterprise Linux version I'm running? Ideally, I'd like to get both the major and minor release version, for example RHEL ...
65
votes
15answers
11k views

Hundreds of failed ssh logins

Every night I get hundreds, sometimes thousands, of failed ssh logins on my RedHat 4 server. For firewall reasons from remote sites, I need to run on the standard port. Is there anything I should be ...
55
votes
2answers
12k views

Why is it so difficult to upgrade between major versions of Red Hat and CentOS?

"Can we upgrade our existing production EL5 servers to EL6?" A simple-sounding request from two customers with completely different environments prompted my usual best-practices answer of "yes, but ...
41
votes
3answers
6k views

How to handle security updates within Docker containers?

When deploying applications onto servers, there is typically a separation between what the application bundles with itself and what it expects from the platform (operating system and installed ...
38
votes
6answers
4k views

How can you tell what a server actually does? [closed]

I've been handed 3 Linux boxes, 1 front facing with apache on it and another 2 which, as far as I can tell, don't do an awful lot. All running on Redhat. The question is simple: How can I tell what ...
34
votes
1answer
8k views

Why are my XFS filesystems suddenly consuming more space and full of sparse files?

I've run XFS filesystems as data/growth partitions for nearly 10 years across various Linux servers. I've noticed a strange phenomenon with recent CentOS/RHEL servers running version 6.2+. Stable ...
32
votes
5answers
7k views

How do admins maintain user accounts across hundreds of linux servers?

Dealing with hundreds of RHEL servers, how can we maintain local root accounts and network user accounts? Is there an active directory type solution that manages these from a central location?
28
votes
6answers
5k views

Hardware Firewall Vs. Software Firewall (IP Tables, RHEL)

TL;DR My hosting company says IP Tables is useless and doesn't provide any protection. Is this BS? I have two, co-located servers. Yesterday my DC company contacted me to tell me that because I'm ...
27
votes
7answers
5k views

Reasons to disable / enable SELinux

In the line of this question on StackOverflow and the completely different crowd we have here, I wonder: what are your reasons to disable SELinux (assuming most people still do)? Would you like to ...
26
votes
5answers
45k views

How to install git to red hat enterprise linux 5.3 x64?

How can I configure yum to use some repository which has git rpms?
25
votes
3answers
11k views

The XFS filesystem is broken in RHEL/CentOS 6.x - What can I do about it?

Recent versions of RHEL/CentOS (EL6) brought some interesting changes to the XFS filesystem I've depended on heavily for over a decade. I spent part of last summer chasing down an XFS sparse file ...
19
votes
3answers
14k views

What is needed for a linux service to be supported by chkconfig?

I am trying to add to the auto start at boottime a linux service through the chkconfig -add <servicename> and I get a message saying service <servicename> does not support chkconfig ...
19
votes
4answers
10k views

Common wisdom about Active Directory authentication for Linux Servers?

What is the common wisdom in 2014 about Active Directory authentication/integration for Linux servers and modern Windows Server operating systems (CentOS/RHEL-focused)? Over the years since my first ...
19
votes
2answers
1k views

Best Practices for updating a previously unmaintained server RHEL5.7

A new RedHat EL5.6 server has been recently put under my care. It is immediately obvious that, for the previous 12 months, little to no attention has been given to any sort of package updates. ...
18
votes
7answers
73k views

What is the value of JAVA_HOME for CentOS?

I have install java through yum on CentOS, however another java programme needs to know what the JAVA_HOME environmental variable is. I know all about setting environmental variables, but what do I ...
18
votes
3answers
50k views

How do I enable apache modules from the command line in RedHat?

How do I enable apache modules from the command line in RedHat? On Debian/Ubuntu systems I use a2enmod to enable modules from the command line. Is there an equivalent for RedHat/CentOS type systems? ...
17
votes
5answers
29k views

How to update cURL CA bundle on RedHat?

I am running into issues where the CA bundle that has been bundled with my version of cURL is outdated. curl: (60) SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL ...
17
votes
6answers
37k views

KVM Guest installed from console. But how to get to the guest's console?

I'm trying to install a fully virtualized guest (Fedora 14 x86_64) on KVM (RHEL 6), using command-line only (both hypervisor and guest). It goes without errors, and without a tangible result . I'd ...
16
votes
1answer
649 views

Install APC RedHat

i am trying to install apc on redhat so i did: pecl install apc i said yes to: Use apxs to set compile flags (if using APC with Apache)? [yes]: and i get this: checking for re2c... no ...
16
votes
3answers
9k views

SElinux: allow httpd to connect to a specific port

My system is running CentOS 6.4 with apache2.2.15. SElinux is enforcing and I'm trying to connect to a local instance of redis through my python/wsgi app. I get Error 13, Permission denied. I could ...
16
votes
3answers
13k views

Open source alternative for Canonical Landscape? [closed]

From Canonical: Landscape is an easy-to-use systems management and monitoring service that enables you to manage multiple Ubuntu machines as easily as one through a simple Web-based ...
15
votes
5answers
30k views

How to restart nginx?

For me, I run "killall nginx" and start it by "sbin/nginx", anyone has a better restart script? BTW: I install nginx from source, i do not find 'service nginx' command or /etc/init.d/nginx
15
votes
3answers
21k views

How to unzip files bigger than 4GB?

I'm using RHEL 5.6 and unzip-5.52-3.el5. I'm trying to unzip a big file, but I get the error: unzip -o test.zip -d unzip/ error: Zip file too big (greater than 4294959102 bytes) Archive: test.zip ...
15
votes
7answers
17k views

Automatically check for Security Updates on CentOS or Scientific Linux?

We have machines running RedHat-based distros such as CentOS or Scientific Linux. We want the systems to automatically notify us if there are any known vulnerabilities to the installed packages. ...
14
votes
2answers
1k views

How to prevent users from extending their window of valid login

Been working on some security hardening procedures for a RedHat box, and I wanted to know if would be possible to prevent a user from changing his password, once it's expired. For one of our clients ...
14
votes
3answers
28k views

How to list RPM dependencies?

Our production server is running CentOS release 5.2 (Final). How do I see/get/list all the dependencies of an already installed RPM package? For example: SQLite v3.3.6 is already installed in the ...
14
votes
2answers
3k views

What does the new full stop / period mean in the RHEL6 ls output?

We have scripts looking at the output of ls -l output for permission information that have been failing recently on RHEL v6 systems which appear to be showing an extra . at the end of the permission ...
14
votes
5answers
3k views

What dir should I deploy Rails apps into?

What would be a reasonable and logical directory into which to deploy my production Rails apps on a Linux system? Some candidates... /var/rails <= There's a /var/www so this would be consistent ...
14
votes
1answer
14k views

Is there still a use for irqbalance on modern hardware?

This question has been asked before, but I believe that the world has changed enough for it to be asked again. Does irqbalance have any use on today’s systems where we have NUMA-capable CPUs with ...
13
votes
3answers
2k views

Does my Oracle DBA need root access?

My Oracle DBA Colleague is requesting root access on our production servers. He is arguing that he need it to perform some operations like rebooting the server and some other tasks. I do not not ...
13
votes
2answers
6k views

Linux containers (LXC) on Red Hat/CentOS EL6 - lxc-create versus libvirt?

It's tricky trying to stay within the good graces of Red Hat and still plan for system longevity... I've been a proponent of Linux Containers (LXC) for over a year. My initial installations were ...
13
votes
4answers
4k views

How to identify NICs that are connected to the same switch from a Linux box?

Initial Setup As a Linux administrator you have installed a fresh Linux box with 6 NICs eth0 to eth5. The eth0 interface is correctly configured and all other interfaces are currently up but without ...
13
votes
2answers
34k views

Upgrade CentOS 5.x to CentOS 6.x - tips and techniques

Now that CentOS 6.0 is making its way to the various mirror sites, I wanted to solicit opinions on the upgrade process. In working with the commercial RedHat 5.6 and 6.x distributions for the past few ...
13
votes
3answers
2k views

Pros and Cons of a Decentralized Puppet Architecture

We have around 300 RHEL servers that are currently connecting to a Puppetmaster server. However, we have noticed some performance bottlenecks and it is the point of failure in our system. I am ...
12
votes
3answers
5k views

How can I diff two Redhat Linux servers?

I have two servers that have should have the same setup except for known differences. By running: find / \( -path /proc -o -path /sys -o -path /dev \) -prune -o -print | sort > allfiles.txt I ...
12
votes
3answers
7k views

Persistent ip rule on Linux (Redhat)

How can I configure a persistent ip rule on Linux (specifically Redhat based distros)? Is there no built in method? Is my only option adding to /etc/rc.d/rc.local or creating my own rc.d script? ...
12
votes
1answer
12k views

What the heck is gssapi-with-mic?

Debugging a Nagios warning on ssh, I've discovered that gssapi-with-mic is causing long lags in authentication. I've turned it off, but what exactly am I missing? I gather that GSSAPI is a tool for ...
12
votes
1answer
2k views

Linux - if I change the hostname, which services need to be restarted?

I'm making some system hostname changes across a few environments and this got me thinking... When I change a server's hostname (live), what needs to be modified and which system services require a ...
12
votes
3answers
1k views

on Red Hat Enterprise and CentOS, what is creating /var/run/reboot-required?

On CentOS 5.8+ and Red Hat Enterprise 6+, when installing/updating packages, I notice a flag file /var/run/reboot-required is created when appropriate. On Ubuntu (and Debian too, I'm guessing), if ...
11
votes
4answers
6k views

Should I avoid putting two SSDs in a RAID1 configuration due to performance degradation?

I have a workstation system that will have two 64GB industrial SSDs, and the plan is to have both disks in a RAID1 configuration for redundancy which is set up in the kickstart. The system will be ...
11
votes
5answers
6k views

Quick way to restore or reload /etc/fstab settings?

I'm working with a complex /etc/fstab on a RHEL 6.x-based server. The system has a variety of mount options in use across eight partitions, including several bind mounts. I'm testing options and their ...
11
votes
2answers
56k views

How do I know if IP Multicasting is enabled on my network?

Is there a way to know if the Red Hat Linux Servers on my network have IP Multicasting enabled? The output that I get by running the cat /proc/net/igmp command is the following Idx Device : Count ...
11
votes
2answers
375 views

Name resolution difference between CentOS and Debian

I have a small Java program that loops calling InetAddress.getByName("example.com") every second. When I run it on a CentOS 6.4 box using 'strace -f' I see that /etc/resolv.conf is opened and read ...
10
votes
5answers
863 views

How to make my boss understand that a server fault is a bad thing?

I'm currently working in Tokyo for a smaller company that has just started serious online business. Recently we have been hitting the maximum open files issue on a rented VPS server causing services ...
10
votes
3answers
2k views

Why not use vmware tools for time synchronisation?

We have two VMWare environments running a bunch of (mainly) Redhat 5.9 and 6.4 guests. We are having issues with time drift (minutes ahead per week). We use ntp, syncing to the local domain ...
10
votes
2answers
46k views

How to set the domain name on GNU/Linux?

Similarly to hostname that can be changed in different ways: temporarily using the hostname command permanently using /etc/hostname (or /etc/sysconfig/network or /etc/HOSTNAME, these files are used ...
10
votes
3answers
28k views

How to “restart” particular network interface on RHEL?

In RHEL, instead of using service network restart command, how can i restart a particular network interface, lets say "eth1", with only one command. "Only one command" because that is the only ...
10
votes
2answers
3k views

yumdownloader vs repotrack

I'm working on CentOS 6.3. Recently I come across repotrack from yum-utils. yumdownloader --resolve and repotrack looks very similar, but it looks like yumdownloader download only part of ...
10
votes
4answers
14k views

How to change the time cron.daily is run in linux

I have a script in cron.daily that runs at a certain time every morning. I need to change the time that it is run. How do I change the time cron.daily runs the scripts?