10. Firewalls filter information coming from the Internet into your private network or computer system. If incoming packets of information is flagged by the firewall’ filters, it’s not allowed through.
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12. Information travelling from inside the firewall to the outside is monitored for specific defining characteristics, then incoming information is compared to these characteristics.
34. Web Server and Web Site Security Why we need to validate?
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36. You want to ensure that the correct data is going into the fields set in the tables.
37. You don't want alphanumeric characters going into fields that require numeric characters only.
38. Some fields might require specific information to be entered in a specific format, for example email addresses.
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40. Client Side Validation will often be done with JavaScript whilst Server Side validation would be performed with a server side language such as PHP or ASP.
41. There are other reasons you would validate your web forms and that is due to vulnerabilities.
45. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed.
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47. Web Server and Web Site Security What is Cross-Site Scripting?
48. Web Server and Web Site Security Preventing Cross-Site Scripting
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51. Finally, if your form is submitted using the POST method, you should refer to the parameters using a $_POST rather than $_REQUEST, which also helps to avoid certain types of attacks by ignoring information appended to the URL via the query string.