Typical port numbers: Well known and registered Ports
If the port numbers distinguish three groups: well known ( 0-1023 ) ports, registered ports ( 1024-49151 ) and dynamic / private ports ( 49152-65535 ). The Well – known ports include the well-known numbers for popular services such as HTTP, IMAP , POP3 , SMTP , Telnet , FTP , to name a few. TCP and UDP use often but not always the same port numbers, some port numbers are also only one of the two protocols used.
Registered ports are required for certain applications from manufacturers who installed one user. The administration tool for Linux Webmin server on port 10000 is one example. Or SIP to port 5060 ( SIP takes many VoIP services use and is an alternative to the proprietary Skype protocol). Or 3306 is used to access MySQL databases (MySQL a more widespread database that is used especially on Linux systems , and often in conjunction with the scripting language PHP). 8080 and 8008 are also relatively well-known port numbers because they are taken as an alternative to 80 ( if, for example, two Web servers running simultaneously on a system to operate , for example, an Apache and IIS, or an additional web server for testing purposes ).
The port list on your Linux computer and Ibm thinkpad t60 battery , see etc / services. In Windows XP, this overview is located at% WINDIR % \ system32 \ drivers \ etc \ services .
The dynamic / private ports are assigned to any application to be fixed and used as required . A list of port numbers can be found here with the IANA. How to proceed with open ports , read on the next page .
Ports Close to hedge
This allows a computer to communicate with the Internet , and must therefore necessarily be open some ports . Each open port is a potential conduit for attackers when listening on the port (that is standing ready ) application has a security hole. To get absolute certainty, would conclude all of the ports , but then no internet connection is possible. Ergo , some ports left open. Thus, a rule of thumb : So many ports as necessary and as few as possible open their doors. Concretely, this means that one service , you do not like , simply stops before one attacker exploits to hack into your system.
The users should know what ports are actually up to date on his computer and ibm thinkpad x61 tablet battery ,and listen to what applications accessible to the ports “. Ports for services that are needed , such as emails, for browsing , instant messaging , or because you do file sharing , should at least be monitored. For example, by a sniffer that records when and which data packets departed on what port to which destination or arriving. Wireshark is a suitable tool for this .
Services you need and therefore can not switch off , you should configure as possible , not that of any computer and ibm thinkpad x61 battery to access is possible, but only from certain computers, for example, only from PCs on your intranet . Under Linux you can access certain services in addition to also control via TCP wrappers ( hosts.allow and hosts.deny ). Also, you should configure your firewall so restrictive as it’s at all possible and reasonable. With a firewall you can protect your computer and data packets only after certain requirements – can happen , for example, only certain IP addresses – .
For each operating system , there are some simple tools that you can determine in seconds which ports are open on your system. These tools you should know and use at least one of them regularly to scan your computer or your home or corporate network gateways , before making an attacker.
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