Intermediate Linux / Unix System Administrator Tutorials

These tutorials assumes that you have strong understanding of Unix like operating systems and very comfortable with most aspects of the Unix/Linux operating system. Familiar with fundamental networking/distributed computing environments is required. ( rss feed )

I am under DoS attack. My cloud based server hosting company asked me to enable TCP SYN cookie protection to save my domain from SYN Attack. How do I turn on TCP Syn cookie protection under Ubuntu or CentOS Linux based server?

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I am in the process of setting Apache and PHP for my small business server. I’m not utilizing file upload functionality in any of my PHP scripts. How do I disallow uploading files under CentOS or Ubuntu Linux based LAMP server?

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How do I use rsync command to sync files to a remote host called web-42.vps running VSFTPD ftp server? Can you give me rsync ftp example for Unix like operating systems?

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I run a BT client and few other server program on Linux. Sometime these programs get overloaded with too many connections and crashes. If I restart my apps, I see lots of old IPs in a TIME_WAIT state. How do I force and and close everything in a TIME_WAIT state under Linux operating systems?

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I have recently started to managing FreeBSD server along with Ubuntu Linux. However, sudo command, always shows me the following error:

zsh: command not found: sudo

How do I solve this problem and use sudo under FreeBSD 9.x system?

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I am a new Python programming user. I am working on user-friendly command-line interfaces, and I want to pass input via the shell args as follows:

./myscript.py filename
./myscript.py in.file output.file
./myscript.py -i in.file -o output.file

How do I pass and parse command-line options and arguments using Python under Unix like operating systems?

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I upgraded my system to RHEL/CentOS v6.4 and I am getting the following error for 3rd party packages such as Shorewall and fail2ban:

Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307
Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from create access on the rawip_socket . For complete SELinux messages. run sealert -l 08757ff1-a08d-4c06-a08b-ff5d53712305
Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307
Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from create access on the rawip_socket . For complete SELinux messages. run sealert -l 08757ff1-a08d-4c06-a08b-ff5d53712305
Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307

How do I fix this problem?

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