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Windows

Firefox: Add a Trusted CA

The default Firefox comes with certificates from well-known commercial CAs. My ISP is also CA and Firefox cannot verified it because the CA is not recognized. How do I force Firefox to accept my ISPs certificate?
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Adobe Photoshop Alternatives For Linux Desktop

I need Photoshop alternative under Ubuntu Linux for basic editing. I know Photoshop can be run using Wine but I'm not able to afford expensive software for just basic editing. Can you suggest a few free FOSS apps that works as alternatives to Photoshop under Ubuntu or Fedora Linux desktop operating systems?
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PHP Add Captcha Protection To Web Forms

I own a small business website. However, bots started to abusing my forms such as contact.php. How do I stop bad bots from abusing my site? How do I tell if PHP form is submitted by a person or a script?
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I've ssh gateway behind my NAT firewall. So all users must first login to my gateway host from the internet and then login to other machines on the LAN. This works great for cli based apps. However, few users would like to run x apps from internal LAN hosts and tunnel X display through intermediate ssh gateway and display back output on their local system. For example, from localsystem user makes connection as follows:

ssh -X user@gateway.example.com
ssh -X user@somelan.example.com

X forwarding fails with an error:

Error: Can't open display:

How do I fix this problem and allow users to use X apps with my intermediate Linux / BSD gateway?
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Samba Restrict IPC$ ( list of shared resources )

The IPC$ share allows users to anonymously fetch a list of shared resources from a server. It can be used as a point of attack into a system. How do I disable or limit IPC$ under Samba to certain subnet such as 10.0.0.0/8?
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What is the difference between authentication and authorization? Why it is important to understand difference between the two? Authentication vs. Authorization -- what are they and how do they differ?
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Q.How do I find out the DNS authority record (SOA) for any DNS domain under UNIX / Linux shell?
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