Red Hat Certified Engineer (RHEL 4) Certificate no: 804005914618184
Verify here.
Cisco Certified Network Associate Certificate no:
Verify here.
Brainbench Transcript ID: 2453560
Useful page to show how FDM/(a)synchronous TDM works..
http://williams.comp.ncat.edu/Networks/multiplexing.htm
I keep forgetting the key differences between passive and active FTP.
Here’s a good link.. http://slacksite.com/other/ftp.html
When I used PHP’s mktime() on FreeBSD for dates prior to Jan 1, 1970, it was fine. Used the same code on RHEL 3, it gave me an incorrect value (-14462).
This is due to glibc library in some OS not allowing negative timestamps: http://bugs.php.net/bug.php?id=20048.
Read http://phplens.com/phpeverywhere/adodb_date_library for a solution to this issue.
cPanel sucks.. Poorly coded, worded, packaged. Almost-decent documentation, but looks messy and unprofessional. Plesk is much better!
phpWiki won’t run properly when installed from cPanel.
It will print out this error message:
lib/Request.php:299: Warning: ob_start(): output handler ‘ob_gzhandler’ cannot be used after ‘URL-Rewriter’ or something
This can be fixed by uncommenting 1 line in index.php:
define(’COMPRESS_OUTPUT’, false);
UPDATE: Not sure if this is still valid, since I found this issue in March 2005.
FixedOrbit provides comprehensive information regarding ASs. Very useful to determine/verify an ISP’s uplinks/peers.
Shows some statistics on IP assignment/allocation as well as the major ISPs with best uplinks.
UPDATE: I believe FixedOrbit does not serve up-to-date information, but cidr-report does.
By default, Apache distribution shipped with RHEL is compiled with a hard limit of 300 FDs. A busy server requires a lot more..This is how I increased the FD hard limit based on SW-Soft’s FAQ: http://faq.sw-soft.com/index.php?ToDo=view&questId=172&catId=42
A bit outdated, but that’ll do! 
Add the following line to /etc/sysctl.conf:
fs.file-max = 131072
Run the following shell command:
# sysctl -w fs.file-max=131072
Edit __FD_SETSIZE value in /usr/include/bits/typesizes.h to:
#define __FD_SETSIZE 32768
(before, it is 1024)
Find httpd’s source rpm (try rpmfind or Google) and rebuild the package.
xmlto and pcre-devel are required, install both with up2date.
Other craps will be installed too:
pcre-devel xmlto docbook-dtds docbook-style-xsl passivetex sgml-common tetex xml-common xmltex tetex-fonts tetex-latex
Feel free to remove them once package has been rebuilt.
To rebuild the httpd rpm from the source rpm:
rpmbuild –rebuild sourcerpmfilehere.src.rpm
Once the custom binary rpm is ready, install it with -Uvh –force
Although the rebuild process produces 4 rpm files, I think only the httpd rpm is required.
Restart apache with the following commands:
/usr/local/psa/admin/sbin/websrvmng -a -v (not sure why this is needed)
service httpd restart
Valid for Plesk 7.5.
Having separate secondary NS for Plesk servers will be difficult to manage. To ease the process, I came up with an idea of using PowerDNS’ supermasters feature.
Just shove in the IP of the Plesk server, the name of the secondary NS and the server name to the supermasters table.
During initial touch-up of the Plesk server, make sure while modifying the DNS zone template to use THAT Plesk server as the first NS record. Otherwise it would cause problem with wrong SOA name causing PowerDNS not recognizing AXFR sent by the Plesk server.
Also make sure PowerDNS IP is included in the allowed list of AXFR on Plesk!
Some useful queries for PowerDNS’ SQL:
delete records.* from records, domains where records.domain_id = domains.id and domains.account = ‘SERVERNAME’;
delete from domains where account = ‘SERVERNAME’;
Valid for Plesk 7.5.
While executing updatedb, if it comes up with an error message:
updatedb: create_db(): chdir: No such file or directory
Make sure the directory, in which the shell is currently in, exists.
If drwebd doesn’t want to start, with the following error message:
Plesk authorization failed: HTTP request error [6]
Error: Plesk Software not running.
Make sure localhost is resolving correctly to 127.0.0.1. Check /etc/hosts!
Valid for Plesk 7.5.
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