It turns out some exploit writers don’t want us anywhere near their servers.
The people who created the Neutrino exploit kit are using network level OS finger printing to block access at the network level to Linux systems.
An interesting read and a positive move for us Linux Desktop users.
I needed to quickly export all the articles in a WordPress install to separate html files. There were over 400 posts so a copy and paste was not an option. The quickest way to do this was to export it using the built in export option, then process it using php.
I have been playing around with a couple of modules and monitoring their memory usage. I wanted to clear the caches and buffers to give me a clearer picture of memory usage.
This command is handy for clearing them out.
sync && echo 3 > /proc/sys/vm/drop_caches
When you run
after running the above command you will see the buffers and cached values are either zero or very low. and the Total/Used/Free columns are much clearer.
Please do NOT do this on a live production server unless you know what you are doing.
I had a client who ordered a new server for me to configure. The memory was not what was ordered so I checked out all the other hardware was in order as well.
The hard drives were supposed to be SSD’s but they were connected to a PERC Raid controller. This command allowed me to view them.
smartctl -a /dev/sda -d sat+megaraid,00
smartctl -a /dev/sdb -d sat+megaraid,00
If you don’t have Smartmon installed.
yum install smartmontools
If you get “relay access denied” error messages on mailman and mailman messages are not going out then check to see if you have
::1/128‘ and ‘
127.0.0.1‘ in your whitelist in email settings. This fixed it on a newly migrated server for me.
I have used this technique for a few years now so thought I should post it here as it doesn’t appear to break.
I started getting a “couldn’t save sent message” error message in thunderbird.
I logged onto the server and restarted courier-imapd and postfix and retried. Still the same error.
I checked the maillog and found this error.
Mar 12 17:33:53 plesk postfix/postfix-script: warning: not set-gid or not owner+group+world executable: /usr/sbin/postdrop
As usual, a quick run of the command
Confirmed it was a problem,
So I ran the fix permissions command.
Apparently this is not a well known command so I have posted here.
Just had a client call me due to the fact all the sites on his server were down.
A quick check on disk space and the hard disk was full. This is always the first thing to check when the server is up but sites are down.
I then check each of the root folders in turn to find out which one is causing the problem. This command is so useful and I have been using it for years or variations that I thought I would post just in case.
du -Sh | sort -rh | head -n 5
I always check /var first as this has logs, mail and lots more in it.
The GPG keys listed for the “CentOS / Red Hat Enterprise Linux 6 – atomicrocketturtle.com” repository are already installed but they are not correct for this package.
Atomic are moving everything under one key. To fix this error run this command;
rpm --import https://www.atomicorp.com/RPM-GPG-KEY.atomicorp.txt
Then edit /etc/yum.repos.d/atomic.repo
change the following line
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY.art.txt
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY.atomicorp.txt
We needed to analyse the from, to and subject on one of our servers to deal with a persistent spammer.
Add this to your header_checks