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1500 questions
73
votes
5 answers

Active Directory explained

If you had to explain Active Directory to someone how would you explain it?
user6848
73
votes
11 answers

How can I choose between using my ISP's DNS, or Google's 8.8.8.8?

It seems like a good idea to use Google's public DNS 8.8.8.8 and 8.8.4.4 because it's really fast -- much faster than my own ISP's DNS! -- and probably more reliable, too. That seems like a ridiculously quick win for me, and much easier to…
Torben Gundtofte-Bruun
  • 1,204
73
votes
4 answers

Is there a maximum size for content of an HTTP POST?

Is there a maximum size for an HTTP POST? And if there is a max size, is it determined by the protocol or is it at the discretion of the server?
user11480
73
votes
6 answers

Forcing the from address when postfix relays over smtp

I'm trying to get email reports from our AWS EC2 instances. We're using Exchange Online (part of Microsoft Online Services). I've setup a user account specifically for SMTP relaying, and I've setup Postfix to meet all the requirements to relay…
John Whitlock
  • 1,207
73
votes
3 answers

How do I change the privileges for MySQL user that is already created?

I understand how to create a new user with privileges, but what is the correct way to change privileges for users that are already created? We are running a DB audit and some of the users have way more access then is needed. Plus I don't know the…
Clutch
  • 980
73
votes
10 answers

Linux: how to explicitly unswap everything possible?

I've launched something that took lots of memory and now everything lags a lot. I guess all applications' memory has gone to swap in order to free some space for the memory-intensive process, and now everything is slowly returning to RAM when…
kolypto
  • 11,588
73
votes
11 answers

apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

I keep getting this warning when I (re)start Apache. * Restarting web server apache2 apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName ... waiting apache2: Could not reliably determine…
user35402
  • 1,171
  • 3
  • 12
  • 19
72
votes
6 answers

Could not resolve host: mirrorlist.centos.org Centos 7

If you are reading this after 2024 mirrorlist.centos.org doesn't exist anymore. As noted by @user202729 in notes check this reply. I have a fresh install of latest centos 7 [root@localhost ~]# cat /etc/centos-release CentOS Linux release 7.4.1708…
Albano Albanese
  • 823
72
votes
7 answers

Redis (error) NOAUTH Authentication required

I get the error: (error) NOAUTH Authentication required. When in redis-cli and trying to display the KEYS *. I've only set a requirepass not an auth afaiac. I'm in the redis.conf but do not know what to do.
Karl Morrison
  • 1,701
72
votes
7 answers

What's the easiest way to make my old init script work in systemd?

I don't want to do the right thing by creating a new systemd script, I just want my old init script to work again now that I've upgraded my system to an OS that's using systemd. I've briefly researched how to convert init scripts and how to write…
mlissner
  • 1,130
72
votes
7 answers

how to fix "send-mail: Authorization failed 534 5.7.14 "

I am trying to create e-mail alert on ssh root login so I had to install ssmtp and mail utility. Then I configured ssmtp.conf file as follows : # Config file for sSMTP sendmail # The person who gets all mail for userids < 1000 # Make this empty to…
Connect
  • 831
72
votes
11 answers

How do I check the postfix queue size?

What's the postfix equivalent to sendmail -bp?
Gary Richardson
  • 1,917
72
votes
3 answers

Search ec2 instance by its name from aws command line tool

I have an instance named dev-server-03. Now how can I search all dev-server-* instances from command line? I am using aws cli tool.
Shiplu Mokaddim
  • 933
72
votes
13 answers

104: Connection reset by peer while reading response header from upstream (Nginx)

I have a server which was working ok until 3rd Oct 2013 at 10:50am when it began to intermittently return "502 Bad Gateway" errors to the client. Approximately 4 out of 5 browser requests succeed but about 1 in 5 fail with a 502. The nginx error log…
Nigel Alderton
  • 1,062
72
votes
5 answers

How can I get more info on open pipes show in /proc in Linux?

In Linux if you go digging in /proc//fd often you'll see output like: lrwx------ 1 root root 64 Jul 30 15:14 0 -> /dev/null lrwx------ 1 root root 64 Jul 30 15:14 1 -> /dev/null l-wx------ 1 root root 64 Jul 30 15:14 10 ->…
Kamil Kisiel
  • 12,444
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