My server is having a problem with high cpu usage and 503 error occured all the time for a certain domain which is being hosted on my server together with other websites. The other websites on the same server are working fine. The problem only happens to this domain with the folllowing error:  [Sat Sep 26 12:15:08.831092 2015] [fcgid:warn] [pid 7760:tid 140509674608384] [client 5.157.42.89:44960] mod_fcgid: can't apply process slot for /usr/local/safe-bin/fcgid55.sh /usr/local/directadmin/data/users/aaa/php/aaa.com.ini -d sendmail_from="aaa@aaa.com" -d open_basedir="/home/aaa/:/tmp:/var/tmp:/usr/local/lib/php/:/usr/local/php55/lib/php/" -d mail.log="/home/aaa/.php/php-mail.log", referer: http://aaa.com/   And got around 7-10 process pids @ 100% cpu usage with the same commandline:  /usr/local/php55/bin/php-cgi55 -d sendmail_from="aaa@aaa.com" -d open_basedir="/home/aaa/:/tmp:/var/tmp:/usr/local/lib/php/:/usr/local/php55/lib/php/" -d mail.log="/home/aaa/.php/php-mail.log"   My server is on Centos 6. Directadmin. Nginx with Apache 2.4.16. Php 5.5.
This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.
I have two question concerning information content of qubit.  Question 1: How many classical bits are needed to represent a qubit:  A qubit can be represented by a vector $q = \begin{pmatrix}\alpha \\\beta \end{pmatrix}, ~~ \alpha, \beta \in \mathbb{C}$. So, we need four real numbers to represent it. But when facts that (i) $|\alpha|^2+|\beta|^2 = 1$ and (ii) two qubits which differ in global phase only are indistinguishable, are taken into account, only two real numbers are necessary (angles on Bloch sphere). Moreover, we can choose a precission of the qubit representation (i.e. number of decimal places in $\alpha$ and $\beta$ or Bloch sphere angles) which influence number of classical bits needed to described the qubit.   So, it seems to me that the qubit representation cannot be used for measuring qubit information content but only memory consumption in simulation. Am I right?  Question 2: What is an (effective) information content of qubit:  A superdense coding enable us to send two classical bits via one qubit. But on the other hand you need two entangled qubits prepared in advance.  Given these facts, what is an information content of qubit? One or two classical bits? Or do I need to use another angle of view given the fact that qubits are "continuous" (i.e. described by complex numbers $\alpha$ and $\beta$)? How do I write a mathematical equation for ARIMA (2,1,0) x (0,2,2) period 12 I'm on Ubuntu 16.04.1 at the moment, and system windows like the Files window, Terminal or System Software open behind the Unity launcher, which means they are partially hidden behind it. I can move them with Alt+F7, but I'd like a more permanent solution to this problem. Is this intended behavior (with plain XeTeX):  \input tikz \tikz\draw[dashed] node {$3T\over4$}; \bye   It renders as: !?  The fraction line is dashed, too! Is this intentional? Is there something I can do to change that? I know I can separate the fraction into its own node, but other than that? Short story (50s? 60s?) with a man trapped inside a sentient cave I have seen many programs consisting of structures like the one below  typedef struct  {     int i;     char k; } elem;  elem user;   Why is it needed so often? Any specific reason or applicable area? Derivative of determinant of a matrix I would like to know how to calculate:  $$\frac{d}{dt}\det \big(A_1(t), A_2(t), \ldots, A_n (t) \big).$$ Is it possible to create individual power settings for each hard drive? I have a number of different drives that I use for different purposes but I only use two of them frequently. I would like for the others to enter sleep mode when not in use, but never my main two.  Is there any way to edit power saving settings for individual drives? When are you supposed to use escape instead of encodeURI / encodeURIComponent? When encoding a query string to be sent to a web server - when do you use escape() and when do you use encodeURI() or encodeURIComponent():  Use escape:  escape("% +&amp;=");   OR  use encodeURI() / encodeURIComponent()  encodeURI("http://www.google.com?var1=value1&amp;var2=value2");  encodeURIComponent("var1=value1&amp;var2=value2"); What is the need of acceleration? As we can usually predict the various forces that a body might be undergoing based on its position and its velocity.Hence what is the need of acceleration? We know  speedup brute-force attacks two times faster in block ciphers (e.g brute-forcing 128-bit keys take $2^{64}$ operations, not $2^{128}$). That explains why we are using 256-bit keys to encrypt top secrets. But  on AES shows brute-forcing AES-256 take $2^{100}$ operations. Does this attack work with Grover's search to make AES cipher quantum unresistant? What is the difference between ethics and morals? I am currently writing an essay on artificial moral agents, and I need to explain the difference between ethics and morals. However, I am finding it really hard to find a good book or research paper which contains a citable definition.   Could someone point me in the right direction? I have a windows 7 user who belongs to admin group. I want to execute sc command that requires admin privileges. I DON'T want to open an elevated cmd, want to be able to simply Win+R->Enter command, enter password and that's all. I tried the runas command, but it doesn't seem to work:  &gt;runas /user:me "cmd"   and it asks for a password, and then the command is executed with normal privileges. I know I could use /user:administrator but I don't know the admin pass and I think the admin user (me) should work. Why wasn't Restricted Section of the library better protected? I know that the compiler will sometimes initialize memory with certain patterns such as 0xCD and 0xDD.  What I want to know is when and why this happens.  When  Is this specific to the compiler used?  Do malloc/new and free/delete work in the same way with regard to this?  Is it platform specific?  Will it occur on other operating systems, such as Linux or VxWorks?  Why  My understanding is this only occurs in Win32 debug configuration, and it is used to detect memory overruns and to help the compiler catch exceptions.  Can you give any practical examples as to how this initialization is useful?  I remember reading something (maybe in Code Complete 2) saying that it is good to initialize memory to a known pattern when allocating it, and certain patterns will trigger interrupts in Win32 which will result in exceptions showing in the debugger.  How portable is this? Creating mask file from shapefile using ArcGIS for Desktop? I have a shapefile of Lakes over my study area. Each polygon has attribute information of each lake, name, shape etc. Actually I want to eliminate all lakes from analysis. In other word, I want lakes to have 0 value and the area that out of boundary of lake to have their orginal pixel values. when I do subset using this shapefile, the output is not I want because my shapefile deoesn't have any value outer boundary of lake.   How can I build a proper mask file (inner part of lake has 0 value, outer is 1) using this shapefile in ArcGIS Desktop? A friend's visa has expired in Thailand. How does he get back to the UK? Can jQuery get all CSS styles associated with an element? How can I iterate over an enum? Let $H$ and $K$ be subgroups of a group $G$, and let $HK=\{hk: h \in H, k \in K\}$, $KH=\{kh: k \in K, h \in H\}$. How can we prove that $HK$ is a subgroup iff $HK=KH$?