Tag Archives: Declaration

Highlight Portraits on Photographs by Blurring the Background

Posted on 13. January 2012 by robert

It is a popular artistic means for portrait photos, to highlight the portrait, by bringing the background out of focus. If you do not care for all the technical details, but simply want to know, how to achieve it, can jumpt directly to the Results in brief jump.

Content

1. First approaches to unsharp masking

This is the beginning of the article Highlight Portraits on Photographs by Blurring the Background. View the full article (1679 words, 4 images, estimated 6:43 Min. Reading time)
Posted in See all German articles, Other, Photography, Connect-4 | Tagged , , | Leave a comment

How does the RSA encryption work?

Posted on 11. April 2011 by robert

The question "How does the RSA encryption work?"Can be understood in two ways:

  1. What calculations are needed for the RSA-en- and decryption?
  2. Why do the corresponding formulas work?

Below I will for the RSA-en- and decryption explain the necessary calculations and then briefly outline, why these formulas work.

This is the beginning of the article How does the RSA encryption work?. View the full article (703 words, 1 image, estimated 2:49 Min. Reading time)
Posted in Computer, Encryption | Tagged , | Leave a comment

IPv6 Course part 3: The target- and Source IP Selection (prefix policy)

Posted on 17. March 2011 by robert

In IPv6, it is provided in the standard, that a computer, even closer 1 NIC, has multiple IPs. This may be due:

This is the beginning of the article IPv6 Course part 3: The target- and Source IP Selection (prefix policy). View the full article (680 words, estimated 2:43 Min. Reading time)
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Stun server configure in Pidgin

Posted on 8. November 2010 by falko

In the current version of Pidgin 2.7.5 can be in the settings (Menu / Werzeuge / Einstellungen / Netzwerk) Enter a STUN Server. A STUN server is used to, that a computer (or. In this case, Pidgin) can find, on which public IP address (and what UDP port) He can be reached, when it is itself a local IP, p.E.. has the power 192.168.xy. This is important for file transfers, where between two chat partners usually a direct connection is established.
Unfortunately, the designation “STUN-Server” Pidgin in the settings not quite right. Because Pidgin is realistic to expect there not to specify the STUN server, but the specification of a domain, within it then looks for a STUN server.
An example to illustrate:
The STUN server of the provider “Sipgate” has address stun.sipgate.net.
Now I would have expected, that you just must enter this address in pidgin, if you want to use the STUN server from sipgate. – Not at all!
In this case, try Pidgin by DNS for a STUN server and asks for:
SRV _stun._udp.stun.sipgate.net
Pidgin is looking for a server that is (SRV) in the domain stun.sipgate.net for the STUN protocol, reached by the UDP is. There is none. But under the domain sipgate.de he would find. And actually – when sipgate.de enters into the Pidgin settings, asks for Pidgin SRV _stun._udp.sipgate.de and receives a response SRV stun.sipgate.net , then uses the pidgin.

Permanent link to this post (209 words, estimated 50 SEK. reading time)
Posted in See all German articles, Computer, Other | Tagged , , , , | 2 Comments

IPv6 Course part 2: Stable IPv6 addresses on the local network

Posted on 17. October 2010 by robert

For IPv6, Network Address Translation (NAT) not provided. Rather, it is among other Purpose IPv6, NAT to make it unnecessary. The corollary, principle that every computer has a publicly accessible IPv6 (However, the protected by the firewall or in the FritzBox. is blocked). It also means, that by default, change the local IPv6 is, if the public IPv6 change.
Also: If you have no fixed IPv6 subnet (and perhaps reasons of anonymity and will not have), then change the default, IPv6 addresses of all computers in local network accessible, if the router gets a new IPv6 subnet. Get the router using 6to4 tunnels are IPv6 subnet, then changes the IP every time IPv6, if the router gets a new IPv4.
In the local network but it can be useful, always use the same subnet. A local server can be configured in a manner, to only accept connections from that subnet. When the Web server is the apache for example with the following commands (“Ababa:Ababa:Ababa” replace the self-chosen prefix, see following paragraph):
deny from all
allow from fd00:abab:abab:abab:/64 192.168.178.0/24

This is the beginning of the article IPv6 Course part 2: Stable IPv6 addresses on the local network. View the full article (800 words, estimated 3:12 Min. Reading time)
Posted in See all German articles, IPv6 | Tagged , , , , , , | 2 Comments