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Red Hat RHEV vs Vmware ESX In 2009, Red Hat launched Red Hat enterprise Virtualization (RHEV) to compete in commercial virtualization market dominated by VMware. RHEV has two components: Red Hat enterprise Virtualization manager(RHEV-M) and managed hypervisor,which could be RHEV-H(RHEV hypervisor, a trim down version of RHEL) or full-blown RHEL 5.5 (64bit) or newer Feature wise, in paper, RHEV looks not too bad, However what will be revealed if dug further into technical details and compared with VMware? RHEV 2.2 ESX 4 Manager Name RHEV-M vCenter Compatible OS Windows 2003 Windows 20008 R2 Windows XP Windows 2003 Windows 2008 Windows 2008 R2 Backend DB Microsoft SQL Server Microsoft SQL server Oracle Application Type Web application (WPF .xbap application) ...

Linux: 20 Iptables Examples For New SysAdmins L inux comes with a host based firewall called Netfilter. According to the official project site: netfilter is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callback function is then called back for every packet that traverses the respective hook within the network stack. This Linux based firewall is controlled by the program called iptables to handles filtering for IPv4, and ip6tables handles filtering for IPv6. I strongly recommend that you first read our quick tutorial that explains how to configure a host-based firewall called Netfilter (iptables) under CentOS / RHEL / Fedora / Redhat Enterprise Linux. This post list most common iptables solutions required by a new Linux user to secure his or her Linux operating system from intruders. IPTABLES Rules Example Most of the actions listed in this post are written with the assumption that they...

Step by step configure SQUID proxy to block HTTP request to specific web pages or web site. In the /etc/squid/squid.conf 1. Find and edit ACCESS CONTROL part and put in the ( acl bad_url dstdomain "/etc/squid/bad-sites.squid" ) as shown in example below. # ACCESS CONTROLS # --------------------------- ----------- **** +++++ #Examples: #acl macaddress arp 09:00:2b:23:45:67 #acl myexample dst_as 1241 #acl password proxy_auth REQUIRED #acl fileupload req_mime_type -i ^multipart/form-data$ #acl javascript rep_mime_type -i ^application/x-javascript$ # #Recommended minimum configuration: acl all src 0.0.0.0/0.0.0.0 acl manager proto cache_object acl localhost src 127.0.0.1/255.255.255.255 acl to_localhost dst 127.0.0.0/8 acl SSL_ports port 443 2083 563 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 2083 563 # https, snews acl Safe_ports port 7...

Squid content filtering: Block / download of music MP3, mpg, mpeg, exec files Q. For security and to save bandwidth I would like to configure Squid proxy server such way that I do not want my users to download all of the following files: MP3 MPEG MPG AVG AVI EXE How do I configure squid content filtering? A. You can use squid ACL (access control list) to block all these files easily. How do I block music files using squid content filtering ACL? First open squid.conf file /etc/squid/squid.conf: # vi /etc/squid/squid.conf Now add following lines to your squid ACL section: acl blockfiles urlpath_regex "/etc/squid/blocks.files.acl" You want display custom error message when a file is blocked: # Deny all blocked extension deny_info ERR_BLOCKED_FILES blockfiles http_access deny blockfiles Save and close the file. Create custom error message HTML file called ERR_BLOCKED_FILES in /etc/squid/error/ directory or /usr/share/squid/errors/English directory. # vi ERR_BLOCKED_FILES...

Squid content filtering: Block / download of music MP3, mpg, mpeg, exec files Q. For security and to save bandwidth I would like to configure Squid proxy server such way that I do not want my users to download all of the following files: MP3 MPEG MPG AVG AVI EXE How do I configure squid content filtering? A. You can use squid ACL (access control list) to block all these files easily. How do I block music files using squid content filtering ACL? First open squid.conf file /etc/squid/squid.conf: # vi /etc/squid/squid.conf Now add following lines to your squid ACL section: acl blockfiles urlpath_regex "/etc/squid/blocks.files.acl" You want display custom error message when a file is blocked: # Deny all blocked extension deny_info ERR_BLOCKED_FILES blockfiles http_access deny blockfiles Save and close the file. Create custom error message HTML file called ERR_BLOCKED_FILES in /etc/squid/error/ directory or /usr/share/squid/errors/English directory. # vi ERR_BLOCKED_FILES...

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Howto: Linux write (burn) data to DVD or DVD/RW In order to write DVD/DVD-RW from shell prompt you need to install a package called dvd+rw-tools. DVD is another good option for backup, archiving, data exchange etc. You can install dvd+rw-tools with following commands. Also note that this package works under *BSD, HP-UX, Solaris and other UNIX like operating systems. Debian installation: # apt-get install 'dvd+rw-tools' Fedora Core Linux installation: # yum install 'dvd+rw-tools' RedHat Enterprise Linux installation: # up2date 'dvd+rw-tools' In order to write DVD you need to install cdrecord tools . How do I write DVD? You need to use growisofs command, which combined mkisofs frontend/DVD recording program. From growisofs man page, " growisofs was originally designed as a frontend to mkisofs to facilitate appending of data to ISO9660 volumes residing on random-access media such as DVD+RW, DVD-RAM, plain files, hard disk partitions. In the co...