ServerChecker's questions

I'm having trouble with a server side cache with an OpenLiteSpeed server. I've tried the following .htaccess trick to try and turn this cache off. Can you tell me a wget command I can use to test my website to see if caching is disabled properly? I need to bust this cache on my website.

RewriteEngine On

RewriteRule .* - [E=Cache-Control:no-cache]

<IfModule mod_headers.c>
    Header set Cache-Control "no-cache, no-store, must-revalidate"
    Header set Pragma "no-cache"
    Header set Expires 0
</IfModule>

<FilesMatch "\.(css|flv|gif|htm|html|ico|jpe|jpeg|jpg|js|mp3|mp4|png|pdf|swf|txt)$">
    <IfModule mod_expires.c>
        ExpiresActive Off
    </IfModule>
    <IfModule mod_headers.c>
        FileETag None
        Header unset ETag
        Header unset Pragma
        Header unset Cache-Control
        Header unset Last-Modified
        Header set Pragma "no-cache"
        Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
        Header set Expires "Thu, 1 Jan 1970 00:00:00 GMT"
    </IfModule>
</FilesMatch>

I have a customer who's got one of these ISPs that implements a cache in order to speed up customer web browsing. This caused him not to download the latest EXE from our NGINX server after an udpate of that EXE from our developers. Is there a way that I can intercept EXE requests from our NGINX and implement a cache-busting header?

NGINX version 1.14.0

Ubuntu Server version 18.04.2

Currently on my Apache 2 (Apache 2.4.7 to be exact) on Ubuntu 14.04, I have this setting:

/etc/apache2/mods-enabled/mpm_prefork.conf

<IfModule mpm_prefork_module>
StartServers                    20
MinSpareServers                 100
MaxSpareServers                 250
MaxRequestWorkers               150
MaxConnectionsPerChild          0
</IfModule>

The server is an 8GB (RAM) Amazon server that does nothing more than load up a three-page signup form for some Google ad campaigns.

I found a script called apachetuneit.sh on the web, but then after awhile the Apache was reporting this error:

[Tue Apr 21 16:45:42.227935 2015] [mpm_prefork:error] [pid 1134] AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting

How can I judge how to set these settings?

I am asking specifically only for how to tune Apache 2.4 and nothing else. This is why this question is different than this question.

What command can I type with Linux where I can watch Apache HTTP web server load in real time?

BACKGROUND: I can type 'top'. That let's me watch overall server load (just look at inverse of Idle % and consider it over a period of time). However, I need to know how to see when Apache is running into critical load and may run out of process handles or something like that.

What Linux command can I type where I can watch MySQL server load in real time?

BACKGROUND: I can type 'top' and watch overall server load (just look at inverse of Idle % and consider it over a period of time). But I need to know how to see when MySQL is running into critical load and may run out of process handles or something like that unless I do something about it.

Unfortunately with a product I rolled out, blackhatters found they could access an unprotected directory where I had the zip files. I use PHP to serve up those zips with readfile(), so normally in my application people do not get to those files by URL. So, to head off the problem, I dropped a blank index.php file in that directory. Trouble is, people who read in the forums what the actual zip file names are can download it by simply typing the URL, and unfortunately my product delivery system is complex and won't let me change the name of that URL.

How do I create an .htaccess file in that directory such that people can't download anything out of it by URL, yet allow my PHP readfile() code to continue to serve up that file with a force dodwnload? Even if you're only guessing -- I'm taking any suggestions at this point. I'll keep trying until I find something here that works.

Again, I just need to block direct browser access to specific zip file URLs that people read about in a forum. I think the PHP readfile() code, which runs through the file system rather than the web access, will continue to work just fine.

How would I create a Bash script that simulates SMTP mail receipt and then drops the result into a Maildir-formatted directory (so that Evolution mail reader could read it)?

I just thought it would be a cool thing for PHP developers to have so that they could test SMTP outgoing mail without having to connect to a real mail server or be frustrated with complex Linux mail configs.

Note -- I'm not interested in the typical SMTP outgoing mail send CLI stuff that anyone can do with the telnet command. Instead, I'm interested in a Bash script that actually receives the STMP email connection from PHP's mail() command, and processes it into a Maildir-formatted directory.

My server is encountering high CPU load (like almost pegged at 100%) so much that the Apache service can't run and we get Apache 500 errors. We used a script to catch this and this is where we discovered that normally the server doesn't run a bunch of processes that look like "/usr/sbin/exim -Mc 1R6Nvz-0006CN-KI". However, when the problem occurs, consistently we find a bunch of processes in memory that say "/usr/sbin/exim -Mc 1R6Nvz-0006CN-KI". We contacted HostGator support and they said indeed that the cause of the problem is Exim Mail Retries (what the -Mc switch is for) and not Apache or MySQL or any other process. They agree with my conclusion on focusing purely on Exim.

HostGator is going to grant me root access today to this dedicated host. I'm brand new to Exim, but know Linux fairly well. What logs, email directories, and Exim config files would you recommend I look at in order to troubleshoot high Exim Mail Retries? Note that this is a CentOS 5 Linux with WHM/cPanel on it.

For instance, things I'd love to see:

• the log file on Exim activity, both success and error
• would like to crack open one of the emails it's trying to retry, in order to see a clue perhaps
• would love to see the Exim config files to see if there's a throttle we can apply so that we don't do all these Exim mail retries at once, but perhaps over a large period of time

I tried following this doc...

https://help.ubuntu.com/community/Git

...but unfortunately the "initialKeyFileName" step is not explained.

I was thinking of bringing up a git service on an Ubuntu server. However, the way me and another programmer operate -- we really want to try and stick to one person working on a project at a time.

How would I make a Bash script to create a check in and check out with git? We want to prevent anyone from checking in code that hasn't already been checked in, and it should error out with the name of the person who has the code checked out.

EDIT: I'm not really interested in using Git with its fantastic diff features. I move 100mph and don't have time to play diff games with the other developers. That's why we're using Git. If the other developers want to play the diff game, they can still do so. But when I check something out, I want it locked to everyone until I check it back in again.

My client tells me they have cloned a VM in VMWare of an Ubuntu Linux server. Now it's my job to get into all the files and find out what still has the old server name of "bishop" and change it to something else. Also, the IP address is changed and I need to search for that too.

How would you typically use find, grep, awk, or sed to find these files and then change them rapidly? In the end, I want to make a Bash script.

Of course, I'm not expecting you to tell me every file, but just want to know the technique for finding files with "x" in it and then switching that rapidly with "y".

On Ubuntu, I copied /etc/init.d/skeleton as a new file and made it "all" executable (just like the others in that directory). In it, I made a "foo" that was just another Bash script in /usr/sbin, but it was special in that it sits in a loop waiting on a named pipe connection from a PHP web page. (More details on that are here, although that's a side topic.)

Because it has to wait in a loop on a named pipe connection, this hung the command up at command line obviously. Not a big deal, because I actually want it to hang and wait on a new connection. But I don't want it happening in the foreground. So, I made start-stop-daemon utilize the --background option.

Okay, it works great for starting and status, but stopping doesn't work -- it leaves the command in memory, as well as the cat /tmp/pipe command I have in my /usr/sbin/foo Bash script. They warn that this could happen when using the --background option on the start-stop-daemon command.

THE QUESTION

So, what's the right way to properly stop /usr/sbin/foo when it's run with start-stop-daemon --background, along with stop any child processes (the cat /tmp/pipe command, for instance) that might be called by /usr/sbin/foo? I mean, I guess I could use killall, but that's kind of deadly. Perhaps you know of a more efficient way?

The purpose here is about adding the 'noatime' property in /etc/fstab. We're running CentOS5.

On both servers A and B, we called a maintenance window with our users and stopped MySQL and Apache services.

On Server A, my client properly installed /var/lib/mysql and /home into separate partitions when I checked /etc/fstab. I was able to set the noatime property and remount the volumes, and when I checked with "mount -l" they showed the noatime property. Indeed, the server performance was much snappier when we fired up MySQL and Apache and told the users to get back on.

On Server B, however, my client just put everything on /. Is there an easy way at command line to break up /home and /var/lib/mysql from / so that we can apply noatime?

I'm just wanting to avoid having to do a complete server OS reinstall and then restoring cPanel accounts again.

With Apache, is it possible to send a 404 status header, but then send valid content? Because that's what's happening right now with http://doubleabody.com on a2hosting.com right now. The web logs show all connections (besides the homepage) to be a 404 status, but then the browsers are receiving valid content after that. This causes something strange to happen. In IE, when it has Friendly HTTP Errors turned on, it's displaying the 404. In IE, with Friendly HTTP Errors turned off, it's not displaying the 404 and is displaying the content just fine. In all other browsers, they seem to be seeing valid content and ignoring the 404 error that the server is recording.

This problem used to not occur until 2 weeks ago, and the only thing that has changed in 14 months on the site has been the Apache system updates like normal. (I will admit that the client asked me to edit the homepage template and show a message to IE users about the problem.)

I want to prove that this is a misconfigured Apache config. I have downloaded the database and the hosting files for this WordPress site, and I'm now going to troubleshoot to see if the same code also has a problem on my workstation.

But the question still stands -- can Apache return a 404 status header and still return valid XHTML after that?

I'm receiving 404 Page Not Found errors (80% of the time) on any links off of http://doubleabody.com/, but only for IE browsers, and only if "Friendly Error Messages" is turned on. Go into IE settings and turn off "Friendly Error Messages", and the problem doesn't come back. Turn "Friendly Error Messages" on again, and the problem comes right back, but only 80% of the time. No other browser except IE has this problem. So far we see this problem in IE8 and IE9.

When I say 80% of the time, I mean that I click a link after clearing browser history and cache and get the 404 message in IE. But then refresh like 4 times, and suddenly the page comes up fine. Turn off "Friendly Error Messages", and the problem comes back. We are seeing this on multiple types of Windows (XP, Vista, Windows 7, Windows Server 2008 in a VM on Ubuntu Linux).

Also, this is only a recent problem of about 2 weeks ago. For several months this website ran just fine on a2hosting.com. So far, a2hosting.com is still troubleshooting and they can't figure the problem out either.

This is a WordPress site that's been loaded up with Pods CMS. It has no other plugins besides Pods CMS. I built a custom WordPress theme and then use the Pods CMS API to pull in content to display. This converted this from a blog into a small business website.

The .htaccess of this site is also the normal WordPress variety.

UPDATE1

Per a request from @JeffAlbert, I am showing what the error logs say when I encounter the 404 from an IE8 browser. This was when I clicked a link called "/map" off the homepage. (Note that I have changed the IP addr for my workstation protection.) Note on the first attempt, it failed. On the second attempt, it went through.

50.0.0.0 - - [25/Mar/2011:00:56:51 -0400] "GET /map HTTP/1.1" 404 9082 "http://doubleabody.com/" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729)"
50.0.0.0 - - [25/Mar/2011:00:56:59 -0400] "GET /map HTTP/1.1" 404 9216 "-" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729)"

And now this is what happens when I click /map again with "Friendly Error Messages" turned off in IE8, where it consistently comes up just fine:

50.0.0.0 - - [25/Mar/2011:01:03:19 -0400] "GET /map HTTP/1.1" 404 9216 "http://doubleabody.com/liftgates" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729)"

And here's the result when I use Google Chrome from Ubuntu Linux, where it works consistently:

50.0.0.0 - - [25/Mar/2011:01:07:20 -0400] "GET /about HTTP/1.1" 404 11801 "http://doubleabody.com/map" "Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.151 Safari/534.16"

I have proftpd running under user proftpd. I have a new virtual server in ProFTPD called "example.com" pointing to /var/www/example.com. I have chowned the /var/www/example.com folder with user "example_com" and group "www-data". I have set the directory as SGID (2775). This permits the FTP user "example_com" to login and upload files and folders, while permitting the Apache process user "www-data" to run the website and read/write to files.

In my proftpd.conf, I have set umask like so:

Umask 2664 2775

My trouble is this. When "example_com" creates a new file, it's setting it as 2644 instead of 2664. And when creating a new directory, it's setting it as 2755 instead of 2775. In both cases, it's missing the "group-writable" permission.

How do I turn on Group Write in ProFTPD globally?

I am running Ubuntu Server 9.10 with ProFTPD, and I also have Webmin.

I have DNS setup for 3 domains, mail setup for 3 domains, as well as Apache2 setup for those domains. They work great.

Now I want to give FTP access for an incoming user, but point them to /var/www/[domain] and have them come in as something like user "ftpuser" but want this to translate to user "www-data" so that web permissions will be correct.

What is the technique to do this?

My client had me deploy some folders out to a bunch of home directories for his customer websites. I did this with a Bash script, but it ended up using the root account permissions.

How do I make a Bash script that takes each folder under /home/user (not hidden files or folders), gets the user and group ownership of that folder, and then does a chown -R {user}.{group} /home/user?

The servers are running CentOS Linux.

Is there another way to run Apache2 securely for multiple end users (like hosting hundreds of blogs) without using CGI mode as required by suPHP?

It just seems so inefficient to use CGI mode for PHP when if we could set up permissions properly, we could host PHP through mod_php perhaps?

I mean, I do want to restrict these users to their home directories for their sites, but don't want any security issues.

I need to create a Bash script to go into every user's home folder, seek out a wp-content folder, create a directory uploads under it, and then chmod 0756 uploads.

How do I achieve this?

I imagine I need to use find with a regexp/regex, and then tell it to run another bash script on the results.