I’ve got a complain from the customer of my recent cPanel server installation that his DNS zones are not replicated by our main DNS servers and therefore they have problems.
Category Archives: webhosting
cPanel: How to replicate DNS zones to external Bind server without views
Posted by admin
on 07/15/2020
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Centos7: “ldconfig : Aborted” error and how to deal with it
Posted by admin
on 02/04/2020
1 comment
On one of my recently installed servers I’ve got customer complain about ffmpeg missing some obscure shared libraries. I went to investigate and met some interesting case
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Sysadmin: Letsencrypt renewal htaccess redirect bypass
Posted by admin
on 05/27/2018
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With increasing role of HTTPS websites (Google pushing everybody to run only HTTPS websites considering regular HTTP as insecure) the service provided by Let’s encrypt becomes critically important. But there is a catch – once you get the certificate and redirect your site to HTTPS using .htaccess you will get a problem renewing certificate because 301 redirect breaks the challenge verification and the command
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certbot-auto renew |
gives an error about authorization problem.
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Sysadmin: Virtualmin and Letsencrypt integration
Posted by admin
on 11/16/2017
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If you are using webmin excellent system for managing virtual host configuration it would make perfect sense to integrate with it the popular certificate authority Letsencrypt that issues completely free SSL certificates.
There are few initial steps that has to be made nside Webmin in order to make it utilize Letsencrypt SSL certificate issuing process for configured virtual hosts. I have successufully configured and used Webmin version 1.831 and certbot-auto 0.12. YMMV.
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Sysadmin: PHP-FPM modular config
Posted by admin
on 10/06/2017
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When you have multilple PHP-FPM pools configured on the server you usually store the configurations under /etc/php-fpm.d. When you have a lot of sites this directory starts looking pretty crowded.
Although when you look inside the typical PHP-FPM pool configuration file you can easily notice that there about only 4 lines that make a difference – everything else is absolutely identical.
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Sysadmin: How to install Letsencrypt on CentOS
Posted by admin
on 09/18/2017
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Since Letsencrypt started their services life became much easier (or less). You can get free valid and secure SSL certificates that are recognized by majority of browsers, but for that you need to do some initial configuration and keep in mind that if you don’t renew all these nice certificates will turn into pumpkin after 2 month.
Here is the one liner command to install certbot-auto in CentOS 6 (requires additional Python 2.7 from EPEL repo)
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yum -y install python27 python27-devel python27-pip cd /usr/local/sbin wget https://dl.eff.org/certbot-auto chmod +x ./certbot-auto export PYTHON=/usr/bin/python2.7 ./certbot-auto register --agree-tos --no-eff-email -m <your@email.address> |
Almost, the same for the CentOS 7 just without Python.
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cd /usr/local/sbin wget https://dl.eff.org/certbot-auto chmod +x ./certbot-auto ./certbot-auto register --agree-tos --no-eff-email -m <your@e-mail.address> |
Here is how quickly request/retrieve certificate for your website on domain.com that is hosted under /home/domain/public_html from command line (presuming that the site is answering on this server already e.g. DNS and web server configured properly)
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/usr/local/sbin/certbot-auto certonly --webroot \ -w /home/domain/public_html -d domain.com -d www.domain.com |
If the request was successful your new certificates could be accessible from /etc/letsencrypt/live/domain.com, where
privkey.pem – is the certificate key, cert.pem – bare certificate fullchain.pem – certificate along with the whole CA chain.
Don’t forget that these are valid for 2 month only. You’ll need to run
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/usr/local/sbin/certbot-auto renew |
after that to get valid certificates.
Sysadmin: how to test your web site before switching DNS
Posted by admin
on 04/25/2017
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How to test your web site after moving it to the new location, before switching DNS and “going live” there? This situation happens every day, even multiple times a day with single page placeholder sites and huge complicated web portals. I thought I’ll just put together simple instruction to refer people to it instead of explaining it over and over every time.
So, in order to test your web site on the new server, before switching DNS settings to the new location you will need to fool your desktop browser to look into new IP location. Here is how to do it.
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Sysadmin: check massive list of urls for HTTP status code reply in single line
Posted by admin
on 03/01/2017
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As I mentioned in previous post I did a few upgrades to EasyApache4 on couple of WHM/cPanel servers recently. While providing with an impressive list of advantages this upgrade could render some of the hosted sites offline because of missing PHP modules and incompatible PHP versions. In order to minimize the downtime all hosted sites has to be verified for availability. There could be easily hundreds of web sites hosted on single WHM/cPanel server and checking all of them manually will take a lot of time. In Linux almost anything could be automated.
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cPanel: Upgrade to EasyApache4 important points to consider
Posted by admin
on 03/01/2017
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So, you also decided to take a leap? It’s about time – a lot of new features are coming with EasyApache4 but in order to reduce downtime one has to be careful in the process.
I’ve done a couple upgrades of a company cPanel servers to EasyApache4 recently – not so easy procedure after all although definitely an improvement to the whole cPanel/WHM ecosystem.
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SSL protocol error 525 for nginx solved
Posted by admin
on 02/28/2017
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I’ve hit an unusual error the other day – I had to configure couple of SSL virtual hosts on Nginx web server. I didn’t expect to see any problems with that – it’s really simple and very well documented. The purpose was to switch Cloudflare CDN crypto option from “Flexible” to “Full”, to avoid unencrypted connection between Cloudflare and the server itself. The tricky part is that you have to have SSL virtual host configured on the server side before doing redirection otherwise you will get redirect loop.
I configured both of the SSL virtual hosts (thought second virtual host with ssl_certificate and ssl_certificate_key commented out) and tried to modify Cloudflare configuration – and then I’ve got 525 protocol error. I turned off the caching and tried to investigate.
I tried to use OpenSSL to troubleshoot SSL connection with “s_client” option, trying to connect to each SSL virtual host directly, bypassing Cloudflare and I saw an interesting picture
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C:\>\openssl.exe s_client -connect vhost.com:443 Loading 'screen' into random state - done CONNECTED(00000190) 16220:error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure:.\ssl\s23_li b.c:177: --- no peer certificate available --- No client certificate CA names sent --- SSL handshake has read 0 bytes and written 210 bytes --- New, (NONE), Cipher is (NONE) Secure Renegotiation IS NOT supported Compression: NONE Expansion: NONE --- |
and more verbosely
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C:\>\openssl.exe s_client -debug -connect vhost.com:443 Loading 'screen' into random state - done CONNECTED(00000190) write to 0x38d670 [0x7a5ea8] (210 bytes => 210 (0xD2)) 0000 - 16 03 01 00 cd 01 00 00-c9 03 01 58 b4 d9 62 af ...........X..b. 0010 - c4 ea 07 a4 a9 ba 2f d9-b4 50 f3 3f 2a 05 89 71 ....../..P.?*..q 0020 - 9b de 7f 70 48 13 fb 0d-e8 88 8c 00 00 5c c0 14 ...pH........\.. 0030 - c0 0a 00 39 00 38 00 88-00 87 c0 0f c0 05 00 35 ...9.8.........5 0040 - 00 84 c0 12 c0 08 00 16-00 13 c0 0d c0 03 00 0a ................ 0050 - c0 13 c0 09 00 33 00 32-00 9a 00 99 00 45 00 44 .....3.2.....E.D 0060 - c0 0e c0 04 00 2f 00 96-00 41 00 07 c0 11 c0 07 ...../...A...... 0070 - c0 0c c0 02 00 05 00 04-00 15 00 12 00 09 00 14 ................ 0080 - 00 11 00 08 00 06 00 03-00 ff 01 00 00 44 00 0b .............D.. 0090 - 00 04 03 00 01 02 00 0a-00 34 00 32 00 01 00 02 .........4.2.... 00a0 - 00 03 00 04 00 05 00 06-00 07 00 08 00 09 00 0a ................ 00b0 - 00 0b 00 0c 00 0d 00 0e-00 0f 00 10 00 11 00 12 ................ 00c0 - 00 13 00 14 00 15 00 16-00 17 00 18 00 19 00 23 ...............# 00d2 - <SPACES/NULS> read from 0x38d670 [0x7ab408] (7 bytes => 0 (0x0)) 4372:error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure:.\ssl\s23_lib .c:177: --- no peer certificate available --- No client certificate CA names sent --- SSL handshake has read 0 bytes and written 210 bytes --- New, (NONE), Cipher is (NONE) Secure Renegotiation IS NOT supported Compression: NONE Expansion: NONE --- |
And then it hit me – I’ve turned on SSL mode on the virtual host and not specified nor certificate no key, then I’ve configured another SSL virtual host with valid certificate and key configured but the SSL is running on the single IP so it’s in SNI mode, sends me an EMPTY SSL SNI negotiation start. In order to avoid the problem I need to have valid certificates for ALL my SNI SSL virtual hosts. After I altered my configuration the problem was fixed.
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C:\>\openssl.exe s_client -connect vhost.com: 443 Loading 'screen' into random state - done CONNECTED(00000190) depth=0 C = FR, ST = Paris, L = Paris, O = Default Company Ltd, CN = localhost verify error:num=18:self signed certificate verify return:1 depth=0 C = FR, ST = Paris, L = Paris, O = Default Company Ltd, CN = localhost verify return:1 --- Certificate chain 0 s:/C=FR/ST=Paris/L=Paris/O=Default Company Ltd/CN=localhost i:/C=FR/ST=Paris/L=Paris/O=Default Company Ltd/CN=localhost --- Server certificate -----BEGIN CERTIFICATE----- MIIDkTCCAnmgAwIBAgIJAOAnX6QNo1rxMA0GCSqGSIb3DQEBCwUAMF8xCzAJBgNV BAYTAkZSMQ4wDAYDVQQIDAVQYXJpczEOMAwGA1UEBwwFUGFyaXMxHDAaBgNVBAoM E0RlZmF1bHQgQ29tcGFueSBMdGQxEjAQBgNVBAMMCWxvY2FsaG9zdDAeFw0xNzAy MjcxNTMxNDhaFw0yNzAyMjUxNTMxNDhaMF8xCzAJBgNVBAYTAkZSMQ4wDAYDVQQI DAVQYXJpczEOMAwGA1UEBwwFUGFyaXMxHDAaBgNVBAoME0RlZmF1bHQgQ29tcGFu eSBMdGQxEjAQBgNVBAMMCWxvY2FsaG9zdDCCASIwDQYJKoZIhvcNAQEBBQADggEP ADCCAQoCggEBAO7bt5v2G3uCouQmWkEawc+E18X3IpQA0+VjS1FoIuClKpgNS7X0 CrPEmQIMTkltsve3a0kPC7UeqMjPObb3wX8i+AvGsoeAXJA4ZQDIiHl4UuqCMLpm F2UKjkLcoxkFlinFq2yYZEk6o9awVKsFY14yN9NUpEIl/daJArtaW/a4B1M8RKRO PqSDFajAGXNUQ59tY+HzKNNRG8+c6Uoq+wTiKvOQYsKkGJysMXMgZ3wrTbWC3pEO FGwWvgjyF1YNWstBPPUZy6nOkQvnw7dkdAr23FA6qfnxhTieF94C2XyI7N5AFtYD 9thJiK+jIYtIQUBiPHHUscpx1agMWXC21jsCAwEAAaNQME4wHQYDVR0OBBYEFPx9 5Wv5QjChS/kCgONa0FcL3ifsMB8GA1UdIwQYMBaAFPx95Wv5QjChS/kCgONa0FcL 3ifsMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQELBQADggEBAFgdmFU4rg2eDQcC neU7A5iwrbJtK2k6HS987yStA+U09gDwCwsJRGWJ+NFJvqyNW2816VeI2yp2+02P liluMjOIQzC/5UVXrac5DmpDz71LR/x6H9ksYm/28PyTCQmtmz+V8TtM3FdPFe+s hNiO5v7LPed0lRzkYjyyXW17VBlta0EbkIMCDdtCvTnMj7IWeBF+/WwgvRB9at67 DYJv5TP4B7wxi2mahDpOYKyzue3k+OaGMqRJGPdm9RQMID99LUcsSd6m/UCJO8AK VvfYwB6cVCkpVIDx4kiZtkKBw/Vgts39d9aJ/tPOGZexwdK6T4yXZ8CPTHGNCO24 V4oznag= -----END CERTIFICATE----- subject=/C=FR/ST=Paris/L=Paris/O=Default Company Ltd/CN=localhost issuer=/C=FR/ST=Paris/L=Paris/O=Default Company Ltd/CN=localhost --- No client certificate CA names sent --- SSL handshake has read 1593 bytes and written 344 bytes --- |