87
votes
24answers
24k views

How do I prevent accidental rm -rf /*?

I just ran rm -rf /* accidentally, but I meant rm -rf ./* (notice the star after the slash). alias rm='rm -i' and --preserve-root by default didn't save me, so are there any automatic safeguards for ...
86
votes
7answers
92k views

How do I share a Git repository with multiple users on a machine?

I have a Git repository on a staging server which multiple developers need to be able to pull to. git-init seems to have a flag very close to what I'm looking for: --shared, except I'd like multiple ...
86
votes
8answers
25k views

Recommended LogParser queries for IIS monitoring?

As Stack Overflow grows, we're starting to look closely at our IIS logs to identify problem HTTP clients -- things like rogue web spiders, users who have a large page set to refresh every second, ...
85
votes
13answers
4k views

10 servers to administer and I'm a history major [closed]

Through reasons that don't warrant exhaustive discussion, I find myself in charge of 10 servers: A domain controller-~500 hosts/~350 users IIS web server-This is where we make our money SQL ...
84
votes
11answers
5k views

Cooling Server Closet - No A/C Is Possible

We're moving into a new office in an old building in London (that's England :) and are walling off a 2m x 1.3m area where the router & telephone equipment currently terminates to use as a server ...
84
votes
12answers
12k views

What solutions exist to allow the use of revision control for server configuration files? [closed]

In an environment with multiple system administrators, I see a few advantages to adding the server config files into a revision control system. Most notable are the ability to track changes, who made ...
83
votes
9answers
19k views

Keeping a linux process running after I logout

I'm connecting to a linux machine through SSH, because I'm trying to run a heavy bash script that makes filesystem operations, and it's expected to keep running for hours. But I cannot leave the SSH ...
83
votes
6answers
25k views

SSH keypair generation: RSA or DSA?

SSH supports two signature algorithms for key pairs: RSA and DSA. Which is preferred, if any? For RSA, what is the minimum acceptable key length?
82
votes
1answer
17k views

Create a public SSH key from the private key?

Let's suppose I have a SSH key, but I've deleted the public key part. I have the private key part. Is there some way I can regenerate the public key part?
79
votes
7answers
18k views

How does CTRL-ALT-DEL to log in make Windows more secure?

When logging into Windows, it says on that page that CTRL-ALT-DEL somehow makes Windows more secure. I have never been able to figure a mechanism where having to press some specific key combination ...
78
votes
14answers
63k views

How do you install Node.JS on CentOS?

I've found numerous installation instructions for Node.js but they all seem so complicated -- I'm not a super sys admin but I can get around. I have yum on the system, but I didn't find any node.js ...
78
votes
8answers
70k views

How to zip/unzip files in Powershell?

Is there a one-liner that will zip/unzip files (*.zip) in PowerShell?
78
votes
2answers
24k views

How do I select which Apache MPM to use?

I'm a little confused between the different MPMs offered by Apache - 'worker', 'event', 'prefork', etc. What are the major differences between them, and how can I decide which one will be best for a ...
78
votes
1answer
3k views

I am under DDoS. What can I do?

This is a Canonical Question about DoS and DDoS mitigation. I found a massive traffic spike on a website that I host today; I am getting thousands of connections a second and I see I'm using all ...
76
votes
12answers
7k views

Transfer 10TB of files from USA -> UK datacenter

I am migrating my server from the USA to the UK from one data center to another, my host said I should be able to achieve 11 megabytes per second. Operating system is Windows Server 2008 at both ...
75
votes
8answers
113k views

Run a .bat file in a scheduled task without a window

I have a scheduled task that starts a batch script that runs robocopy every hour. Every time it runs a window pops up on the desktop with robocopy's output, which I don't really want to see. I ...
75
votes
2answers
31k views

What exactly do the colors in htop status bars mean?

By default, htop shows colored status bars for processors, memory, and swap. From left to right, the bars are colored green, blue, yellow, and red depending on some thresholds. What does it mean when ...
74
votes
2answers
121k views

What is Active Directory Domain Services and how does it work?

This is a Canonical Question about Active Directory Domain Services (AD DS). What is Active Directory? What does it do and how does it work? How is Active Directory organized: Forest, Child ...
73
votes
16answers
8k views

How do I protect my company from my IT guy? [closed]

I'm going to hire an IT guy to help manage my office's computers and network. We're a small shop, so he'll be the only one doing IT. Of course, I'll interview carefully, check references, and run a ...
73
votes
12answers
40k views

How do diff over ssh?

How do I diff files/folders across machines provided that the only connectivity available is ssh?
73
votes
2answers
32k views

IPTABLES - Limit rate of a specific incoming IP

I do not wish to limit the rate of a specific service. My goals is to limit rate based solely on the incoming IP address. For example using a pseudo-rule: john.domain.local (192.168.1.100) can only ...
73
votes
4answers
8k views

Should I quit using Ifconfig?

With the servers that mount Infiniband cards, when I use the ifconfig command, I get this warning: Ifconfig uses the ioctl access method to get the full address information, which limits hardware ...
73
votes
5answers
176k views

Does Windows have a built-in ZIP command for the command line?

Since Windows Explorer (since at least Windows XP) has some basic support for ZIP files, it seems like there should be a command-line equivalent, but I can't seem to find any sign of one. Does ...
72
votes
15answers
72k views

Copying a large directory tree locally? cp or rsync?

I have to copy a large directory tree, about 1.8 TB. It's all local. Out of habit I'd use rsync, however I wonder if there's much point, and if I should rather use cp. I'm worried about permissions ...
72
votes
5answers
18k views

nginx HTTPS serving with same config as HTTP

Is there a way to share configuration directives across two nginx server {} blocks? I'd like to avoid duplicating the rules, as my site's HTTPS and HTTP content are served with the exact same config. ...
72
votes
7answers
25k views

Heartbleed: how to reliably and portably check the OpenSSL version?

I was looking at a reliable and portable way to check the OpenSSL version on GNU/Linux and other systems, so users can easily discover if they should upgrade their SSL because of the Heartbleed bug. ...
72
votes
4answers
12k views

Why is TCP accept() performance so bad under Xen?

The rate at which my server can accept() new incoming TCP connections is really bad under Xen. The same test on bare metal hardware shows 3-5x speed ups. How come this is so bad under Xen? Can you ...
71
votes
6answers
12k views

Why is Enterprise Storage so expensive?

This is a Canonical Question about the Cost of Enterprise Storage. See also the following question: What's the best way to explain storage issues to developers and other users ...
71
votes
4answers
42k views

What permissions should my website files/folders have on a Linux webserver?

This is a Canonical Question about File Permissions on a Linux web server. I have a Linux web server running Apache2 that hosts several websites. Each website has its own folder in /var/www/. ...
70
votes
17answers
26k views

Should network hardware be set to “autonegotiate” speeds or fixed speeds?

We recently had a little problem with networking where multiple servers would intermittently lose network connectivity in a fairly painful-to-resolve way (required hard reboot). This has been going on ...
69
votes
8answers
97k views

How do I create a symbolic link in Windows?

Windows Vista added the ability to create symbolic links to files and directories. How do I create a symbolic link and what are the current consumer and server versions of Windows that support it?
69
votes
6answers
10k views

How can the little guys effectively learn and use Puppet?

Six months ago, in our not-for-profit project we decided to start migrating our system management to a Puppet-controlled environment because we are expecting our number of servers to grow ...
69
votes
19answers
14k views

Why should I firewall servers?

PLEASE NOTE: I'm not interested in making this into a flame war! I understand that many people have strongly-held beliefs about this subject, in no small part because they've put a lot of effort into ...
68
votes
2answers
22k views

How can I see which flags Nginx was compiled with?

How can I check what modules have been added to an nginx installation?
67
votes
6answers
42k views

How to force or redirect to SSL in nginx?

I have a signup page on a subdomain like: https://signup.mysite.com It should only be accessible via HTTPS but I'm worried people might somehow stumble upon it via HTTP and get a 404. My ...
67
votes
8answers
5k views

How to backup 20+TB of data?

We have a NAS server at the company I work for that is being used for storing photography sessions. Each session is approximately 100gb. Over the last couple of years this server has accumulated 10+ ...
67
votes
2answers
24k views

Why does my hostname appear with the address 127.0.1.1 rather than 127.0.0.1 in /etc/hosts?

This may be a bit of a noobish question, but I was taking a look at /etc/hosts on my new Xubuntu install and saw this: 127.0.0.1 localhost 127.0.1.1 myhostname On most 'nixes I've used, the second ...
66
votes
9answers
20k views

How to stop people from using my domain to send spam? [duplicate]

I receive Mailer Daemon messages saying certain emails fail. My domain is itaccess.org which is administered by Google apps. Is there any way I can identify who is sending emails from my domain, and ...
66
votes
12answers
11k views

Is Ping a reliable way to check if a server is available?

In my application I am pinging a server and waiting for a response. I am using this to determine whether the server is available and responsive or not. Is this a reliable way of determining ...
66
votes
1answer
7k views

What happens when you plug two sides of a cable to a single networking device?

What is likely to happen when you plug two ends of a network cable to a single switch/router? Will this create problems on the network, or just be ignored?
66
votes
3answers
31k views

What's the difference between authorized_keys and authorized_keys2?

Just wanted a quick summary of the differences between them and why there are two? Cheers
65
votes
14answers
3k views

What's wrong with always being root?

I have a feeling this is a stupid question, but this is something I've wondered for awhile. I have a VPS and this is my first big linux venture. I am the only person who has access to it. My question ...
64
votes
5answers
38k views

Multiple SSL domains on the same IP address and same port?

This is a Canonical Question about Hosting multiple SSL websites on the same IP. I was under the impression that each SSL Certificate required it's own unique IP Address/Port combination. But the ...
64
votes
6answers
82k views

How can I find out what AD groups I'm a member of?

I'm running a Windows XP desktop in a corporate environment. How can I find out what AD groups I belong to?
64
votes
6answers
47k views

Setting the hostname: FQDN or short name?

I've noticed that the "preferred" method of setting the system hostname is fundamentally different between Red Hat/CentOS and Debian/Ubuntu systems. CentOS documentation and the RHEL deployment guide ...
63
votes
19answers
28k views

Does SpinRite do what it claims to do?

I don't have any real (i.e. professional) experience with Steve Gibson's SpinRite so I'd like to put this to the SF community. Does SpinRite actually do what it claims? Is it a good product to use? ...
63
votes
6answers
125k views

Boot and Install Windows from a USB thumb drive

Installing Windows from a thumb drive is vastly superior to burning a copy to a DVD which will fill some landfill somewhere with toxic stuff. Not to mention it's about 50x faster to install Windows ...
62
votes
13answers
54k views

In my /etc/hosts/ file on Linux/OSX how do I do a wildcard subdomain?

I need to test sub-domains on my localhost. How can I effectively have this result of adding *.localhost.com to m /etc/hosts/ file? If it's not possible, how do I work around this problem? I need ...
62
votes
4answers
34k views

Moving an already-running process to Screen

My office job routinely sees me connected to a Linux box via VNC. Sometimes I start a remote job on the console, and realize later that it runs much longer than expected. (Should have started that ...
61
votes
8answers
33k views

How much network latency is “typical” for east - west coast USA?

At the moment we're trying to decide whether to move our datacenter from the west coast to the east coast. However, I am seeing some disturbing latency numbers from my west coast location to the east ...

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