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1500 questions
213
votes
3 answers

What does a + mean at the end of the permissions from ls -l?

What is the plus sign at the end of the permissions telling me? ls -l total 4 drwxrwxrwx+ 2 benson avahi-autoipd 4096 Jan 27 17:37 docs Here's the context: cat /etc/issue \CentOS release 5.3 (Final) Kernel \r on an \m
bmargulies
  • 2,533
212
votes
6 answers

How do I convert a .cer certificate to .pem?

I have a .cer certificate and I would like to convert it to the .pem format. If I remember correctly, I used to be able to convert them by exporting the .cer in Base64, then renaming the file to .pem . How do I convert a .cer certificate to .pem?
211
votes
5 answers

What is a glue record?

This is a Canonical Question about DNS glue records. What exactly (but briefly) is a DNS glue record? Why are they needed and how do they work?
LanceBaynes
  • 3,237
210
votes
6 answers

Non interactive git clone (ssh fingerprint prompt)

I want to clone a repo in a non-interactive way. When cloning, git asks to confirm host's fingerprint: The authenticity of host 'bitbucket.org (207.223.240.182)' can't be established. RSA key fingerprint is…
qwe
  • 2,147
208
votes
4 answers

Meaning of the buffers/cache line in the output of free

Why does my server show total used free shared buffers cached Mem: 12286456 11715372 571084 0 81912 6545228 -/+ buffers/cache: 5088232 7198224 Swap: 24571408 54528 24516880 I have no idea on…
208
votes
3 answers

Possible to change email address in keypair?

I've created an RSA keypair that I used for SSH, and it includes my email address. (At the end of the public key.) I've now changed my email address. Is it possible to change the email address on the key, or is it part of the key and I would have to…
Ram Rachum
  • 5,411
208
votes
3 answers

How do I ask apt-get to skip any interactive post-install configuration steps?

I have a server build script which uses apt-get to install packages. It then puts pre-written configuration files directly in place, so the interactive post-install configuration dialog in packages such as postfix is not needed. How do I skip this…
jl6
  • 2,685
208
votes
9 answers

How to start/stop/restart launchd services from the command line?

How do I restart, say for example my httpd or afpd, running any Mac OS X >= 10.5 (Leopard-), without having to use the GUI and go to System Preferences -> Sharing and unchecking/checking "Web Sharing"? I'm looking for the canonical equivalent to…
conny
  • 2,469
205
votes
1 answer

What is a challenge password?

I'm setting up SSL on an Ubuntu server. One of fields it asks for as part of setting up the CSR is a "challenge password". What is that? The default is blank. Do I need to enter one?
Will Martin
  • 2,563
205
votes
13 answers

Top level domain/domain suffix for private network?

At our office, we have a local area network with a purely internal DNS setup, on which clients all named as whatever.lan. I also have a VMware environment, and on the virtual-machine-only network, I name the virtual machines whatever.vm. Currently,…
204
votes
9 answers

Heartbleed: What is it and what are options to mitigate it?

This is a Canonical Question about understanding and remediating the Heartbleed security issue. What exactly is CVE-2014-0160 AKA "Heartbleed"? What is the cause, what OSs and versions of OpenSSL are vulnerable, what are the symptoms, are there…
Jacob
  • 9,282
204
votes
5 answers

DNS - NSLOOKUP what is the meaning of the non-authoritative answer?

For some domains nslookup gives me a Non-authoritative answer section. What does this mean? Got answer: HEADER: opcode = QUERY, id = 3, rcode = NXDOMAIN header flags: response, want recursion, recursion avail. questions…
mahen3d
  • 4,682
203
votes
6 answers

SSL Certificate Location on UNIX/Linux

Is there any standard or convention for where SSL certificates and associated private keys should go on the UNIX/Linux filesystem?
John Topley
  • 2,335
201
votes
10 answers

Nginx enable site command

We all know how to enable a website using apache on Linux. I'm pretty sure that we all agree on using the a2ensite command. Unfortunately, there is no default equivalent command that comes with Nginx, but it did happen that I installed some package…
HXH
  • 3,185
201
votes
11 answers

ssh-agent forwarding and sudo to another user

If I have a server A into which I can login with my ssh key and I have the ability to "sudo su - otheruser", I lose key forwarding, because the env variables are removed and the socket is only readable by my original user. Is there a way I can…
Florian Schulze