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60
votes
15answers
9k 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 ...
51
votes
2answers
8k 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 ...
52
votes
5answers
3k views

How should an IT department choose a Linux distribution: Technical reasons

There is a lot of community feeling about what Linux distributions are appropriate for production server environments and what aren't. Some of this is based on the availability of commercial support. ...
29
votes
1answer
6k 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 ...
13
votes
2answers
30k 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 ...
6
votes
6answers
28k views

CentOS 5: How to resolve php53 RPM dependency conflict with php-foo and php-common?

We are running a CentOS 5.6 system, and want to install php53 with php-mcrypt. However, this introduces a dependency conflict between php-common & php53-common. Does anyone have a good workaround ...
7
votes
3answers
32k views

How to find RAID configuration/level and RPM speed having only remote access to the server?

Having only remote access (no physical access), to a server (that is SSH), how do I (or may be is it possible): find out whether it is RAID configured or not? If it is RAID configured, whether it ...
4
votes
3answers
2k views

Update Red Hat Enterprise Linux's Packages Only To Specific Point Release

Let's say that I have one RHEL6.2 64bit server running. Current latest version available is 6.4. Running "yum update" will update my server up to 6.4 straight away. What if I want to update only to ...
11
votes
5answers
4k 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 ...
53
votes
9answers
105k views

What version of RHEL am I using?

How can I determine from the shell with no privileges what the Red Hat Enterprise Linux version is, for example is it RHEL 4 or RHEL 5.1?
16
votes
4answers
4k 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 ...
24
votes
6answers
3k 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 ...
8
votes
3answers
19k views

Install Python 2.5 on RedHat/Centos

Current Python version is 2.4... yum upgrade python Gives Could not find update match for python Do I have to install from source?
7
votes
1answer
4k views

CentOS 5 - realtime patch

Where can I download precompiled CentOS 5 kernel including realtime patch? Or I need to compile it myself (if yes, how to do that)?
2
votes
4answers
7k views

How can I keep the RHEL version static (e.g. RHEL 5.1)?

For compatibility with a program : I need to keep one of our servers in a specific version, for example rhel 5.1 I would like to keep it as updated as possible, but not to change versions. What ...
4
votes
3answers
6k views

second ip address on the same interface but on a different subnet

Is it possible in CentOS 5.7 64bit to have a second IP address on one interface (eg. eth0) - alias interface configuration - in a different subnet? Here is the original config for eth0 more ...
3
votes
1answer
847 views

How can I run Startup Repair on a KVM virtualized Windows Server?

I have Windows Server 2008 R2 running virtualized in a KVM virtual machine. Recently the virtual machine decided to stop booting, and it offered to Launch Startup Repair. However, upon entering ...
2
votes
2answers
8k views

How to change Linux services startup/boot order?

As the question is clear from the title, how do I change Linux services startup/boot order?
1
vote
2answers
2k views

Hardware Requirements & Tuning - Flash Media Server 3.5 Interactive

I am trying to spec out a server to purchase (physically, not rented from someone like softlayer.com) to run an intranet instace of Flash Media Server 3.5 Interactive. In general, the server will ...
25
votes
7answers
4k 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 ...
4
votes
3answers
4k views

Understanding RedHat's recommended tuned profiles

We are going to roll out tuned (and numad) on ~1000 servers, the majority of them being VMware servers either on NetApp or 3Par storage. According to RedHats documentation we should choose the ...
9
votes
3answers
18k views

Sending audit logs to SYSLOG server

I'm running several RHEL based systems which utilize the audit functionality within the 2.6 kernel to track user activity and I need to have these logs sent to centralized SYSLOG servers for ...
12
votes
2answers
4k 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 ...
4
votes
4answers
951 views

Accidentally ran chmod 775 -R / (not ./) on linux server (RedHat)

I accidentally ran "chmod 775 -R /" instead of "chmod 775 -R ./" and changed the permissions for everything and now the server is broke. Anyone know how I can quickly fix this???
6
votes
2answers
9k views

Account Lockout with pam_tally2 in RHEL6

I am using pam_tally2 to lockout accounts after 3 failed logins per policy, however, the connecting user does not receive the error indicating pam_tally2's action. (Via SSH.) I expect to see on the ...
4
votes
1answer
639 views

Mounting a disk from SAN (RHEL 5.9)

Storage admin told me he put a 3TB drive on my server from the SAN and I was asked to mount it. The only information I know is that it's on LUN 1 and that the disk is 3TB. Multipath is setup and I ...
3
votes
3answers
13k views

Update RHEL Servers without Internet Connection

I plan to have a few servers installed with RHEL, but the servers will not have Internet connection. Is it possible to update RHEL servers without Internet connection? Can I download the updated ...
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 ...
6
votes
2answers
5k views

“open files” ulimit: controlling via limits.conf

I'm banging my head on this, and I can't understand why it's not working. I'm hoping that someone can shed light on this, or failing that, give me some suggestions for avenues of investigation. I've ...
5
votes
1answer
2k views

How do I migrate from RHEL 5 to CentOS 5?

I've found myself in charge of installing some software on an old server running RHEL 5. Unfortunately, since it's just a development server now, it no longer rates a license. I'd like to continue ...
1
vote
1answer
188 views

Linux Startup Script + add one command

I need one command line to run at startup. I've tested the command (it re-assosiates an Amazon IP to a Linux Server) and the command run successfully. Just need to know the best method to execute ...
1
vote
3answers
273 views

root login via SSH still enabled after setting PermitRootLogin to 'no'

I'm trying to remove root access and password authentication over SSH to a RHEL server so that all users must access it using keys. So far the key access is set up and working, but I am unable to turn ...
0
votes
2answers
214 views

bash stuck at 3.2-24.el5 (Redhat)

I'm trying to update bash on our Red Hat Enterprise Linux Server release 5.6 server. But it won't find an update later than "3.2-24.el5". I've check and it is vulnerable for the shellshock ...
7
votes
3answers
4k views

Logrotate Successful, original file goes back to original size

Has anyone had any issues with logrotate before that causes a log file to get rotated and then go back to the same size it originally was? Here's my findings: Logrotate Script: ...
6
votes
2answers
21k views

Apache Config: RSA server certificate CommonName (CN) … NOT match server name?

I'm getting this in error_log when I start Apache: [Tue Mar 09 14:57:02 2010] [notice] mod_python: Creating 4 session mutexes based on 300 max processes and 0 max threads. [Tue Mar 09 14:57:02 2010] ...
4
votes
5answers
3k views

Script to delete files older than 30days

Shell script should not delete any files under* root dir*. My* path will be like /export/home/ftp/ ... I did some research and figured out the way for finding and deleting the files older than 30 ...
3
votes
1answer
3k views

Multicast doesn't seem to be working on RHEL 5.5

I'm trying to install Oracle Grid Infrastructure on two machines. Their documentation states: You must enable multicasting for the cluster on the IP address subnet ranges 224.0.0.0/24 and ...
3
votes
2answers
8k views

iptables redirect local connections to remote system / port

I am trying to use SSH to port forward windows machines local port 3389 to a redhat server on some arbitrary port (in the unprivileged region) I have protected behind a firewall, then forward the ...
2
votes
1answer
72 views

Bring process to screen

I am running a process which will take several hours. I would like to disconnect from the server, but I do not want to lose the output to the screen. Is there a way to bring the process back to my ...
2
votes
1answer
980 views

How do I make sure VMware Tools is installed and running?

[root@tst-01 ~]# rpm -qa |grep vmware vmware-tools-libraries-nox-8.6.0-2.x86_64 vmware-tools-foundation-8.6.0-4.x86_64 vmware-tools-libraries-x-8.6.0-2.x86_64 [root@tst-01 ~]# ps aux |grep vmware root ...
0
votes
1answer
539 views

Setting up individually accessible public_html for each user of a linux machine

I have a dedicated server on which I have a site http://www.example.com I need to create a user and: allow him ssh and ftp access into it allow him to access a page such as: ...
0
votes
2answers
562 views

Telnet into Red Hat? [closed]

How do I enable telnet for a Red Hat Linux system?
25
votes
5answers
39k 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?
16
votes
6answers
28k 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 ...
11
votes
3answers
4k 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 ...
25
votes
3answers
9k 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 ...
11
votes
2answers
7k 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 ...
5
votes
7answers
10k views

Automated configuration of ldap authentication for RHEL5 servers

I use puppet for managing our production servers. Under rhel5 the standard way of enabling ldap is to use the authconfig tool. Which works successfully, but isn't really capable with the puppet way of ...
12
votes
4answers
3k 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 ...