What does “error (unexpected RCODE REFUSED)” mean?

If you’re seeing this in the /var/log/syslog on your BIND DNS server: Jul 14 00:56:13 kla-dns-01 named[8255]: error (unexpected RCODE REFUSED) resolving ‘75.1.33.112.in-addr.arpa/PTR/IN’: 211.136.17.105#53 ..it means that a client has asked your server to look up a domain name that your server didn’t know about, and when it forwarded the request to it’s forwarders, the …

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What does “NO_PUBKEY 40976EAF437D05B5” mean?

If you see this when you run “apt-get update” on Ubuntu, “apt” is unable to find the Ubuntu package repository’s key in it’s GPG keyring: Reading package lists… Done W: GPG error: http://us.archive.ubuntu.com precise Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 W: GPG error: http://security.ubuntu.com precise-security …

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What does “mountall: Disconnected from Plymouth” mean?

If your hard disk fills up on your Ubuntu system, you may get the following console message, and be unable to login via SSH: mountall: Disconnected from Plymouth Ubuntu 12.04.5 LTS dbserver ttyS0 dbserver login: What does it mean? Plymouth is the application which provides the graphical “splash” screen when booting and shutting down an …

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How do I encrypt my SSH keys?

To make a new SSH key pair (private + public keys), use ssh-keygen. If you enter a passphrase, the private key file will be encrypted with that password. $ $ ssh-keygen -t rsa -f ~/.ssh/newkeyGenerating public/private rsa key pair.Enter passphrase (empty for no passphrase):Enter same passphrase again:Your identification has been saved in /Users/jsmith/.ssh/newkey.Your public key …

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How do I monitor a server behind a firewall with Nagios?

Nagios comes with a client-side agent called NRPE that the Nagios server contacts on port 5666 to run remote service-checks, but what if the server is firewalled?? There is a solution, using a feature of Nagios called “passive checks”.  Its called that because Nagios will passively wait for the client servers to actively check-in with their condition. …

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What does “VirtualHost overlap on port 443” mean?

Why does Apache report “[warn] _default_ VirtualHost overlap on port 443, the first has precedence” when I start it? If you’re going to be serving HTTP -and- HTTPS, be advised that most Apache2 distributions (including Debian) are missing a necessary “NameVirtualHost *:443” statement in /etc/apache2/ports.conf. Add the line to ports.conf: <IfModule mod_ssl.c> # If you …

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How do I disable all comments on my WordPress site?

Comments on new posts can be disabled under Settings/Discussion in the admin interface. Unclick “Allow people to post comments on new articles “. This, however, will not disable comments on any posts that already exist. For those, you can issue this line of SQL: mysql> UPDATE wp_posts p SET comment_status = ‘closed’, ping_status = ‘closed’ …

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What does “UGFzc3dvcmQ6” mean?

Problem: I’m seeing syslog messages like this from Postfix: Dec 3 18:14:13 mailserver postfix/smtpd[10215]: warning: unknown[109.202.9.80]: SASL LOGIN authentication failed: UGFzc3dvcmQ6 The answer is in the secret language of base-64: $ echo “UGFzc3dvcmQ6” | base64 -D Password: $ ‘UGFzc3dvcmQ6’ is the base-64 encoded version of the string ‘Password:’. When an IMAP client tries to connect …

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