Cheatsheet: Difference between revisions
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== Hosts file == |
== Hosts file == |
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* All operating systems with network support have a hosts file in order to translate hostnames to IP addresses. |
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* The file /etc/hosts started in the old days of DARPA as the resolution file for all the hosts connected to the internet (before DNS existed). |
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* It has the maximum priority ahead of any other name system |
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* Order of name resolution is actually defined in /etc/nsswitch.conf, which usually has this entry: |
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hosts: files dns |
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* This means "try files (/etc/hosts); and if it fails, try DNS." |
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* But that order could be changed or expanded. |
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* As a single file, it doesn't scale well: the size of the file becomes too big very soon. |
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* That is why the DNS system was developed, a hierarchical distributed name system. |
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* It allows any host to find the numerical address of some other host efficiently. |
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* On Linux and Mac OS it is located here: /etc/hosts |
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* On Windows it is under: Windows\System32\drivers\etc\ |
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* The hosts file contains lines of text consisting of an IP address field followed by One or More Host names. |
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* Each field is separated by white space – tabs or spaces. |
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* Comment lines are indicated by an octothorpe (#) in the first position. |
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* Entirely blank lines in the file are ignored. |
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* One name may resolve to several addresses (192.168.0.8 10.0.0.27). |
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* However which one is used depends on the routes (and their priorities) set for the computer. |
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* By editing the hosts files, you can achieve: |
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Block a website |
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Handle an attack or resolve a prank |
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Create an alias for locations on your local server |
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Override addresses that your DNS server provides |
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Control access to network traffic |
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== Check CPU, Memory and HDD == |
== Check CPU, Memory and HDD == |