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High Performance Geoip Blocking in eBpf with XDP - at 2022-11-12 18:09:26

XDP stands for eXpress Data Path and provides a framework for BPF that enables high-performance programmable packet processing in the Linux kernel. It runs the BPF program at the earliest possible point in software, namely at the moment the network driver receives the packet. 1 According to customer needs, we need to drop or pass packets for a list of source countries. This necessity varies by customer, but some use cases include DNS infrastructures having a specific point of presence. So it needs to be highly configurable in terms of source countries and type of the list as block or...

last updated 2022-11-12 18:09:26 by met

Disassembling Hello World in Java - at 2021-09-30 21:00:05

1.6M Repository Results About Hello World. For most, "Hello World" has been the prominent choice of test phrase when beginning journey of learning a new programming language. It's widely used in examples and tutorials. Making a quick search in the Github reveals over 1.6M results so there's no doubt of its widespread use. Java was the second most used language - after HTML - in the search. Writing The Program Software written in Java is usually compiled into Java Bytecode which are then executed...

last updated 2021-09-30 21:48:08 by met

Linux Kernel Overlapping Internet Fragment Bug - at 2020-09-12 13:00:21

Some Linux kernel versions had a bug in their ip fragmentation module which caused system crash during handling of a malformed ip fragment back in 1997. What's an Ip Fragment The "Internet Protocol" allows packets larger than the maximum transmission unit to be sent as smaller fragments. If an internet packet is fragmented; it uses "More Fragments" flag to indicate further coming fragments, "Fragment Offset" field to indicate fragments position and "IP Identifier" field to group fragments. The procedure for handling this in Linux kernel 2.1 is fairly simple. When the ip stack encounters with a...

last updated 2020-09-15 16:13:24 by met

The Idea Of Makefile Blog - at 2020-06-04 18:01:21

The meme about this post, by @vincentdnl. Nowadays, even the simplest static website generator are overly complicated and requires too much effort to learn and customize. A possible solution to this problem was use of easily accessible tools -if not already shipped with distro- with the power of GNU Make. First think I did was searching similar implementations with a makefile but I had no luck except for some generators which basicly call a script already written in a high level language and it lacked the extensibility...

last updated 2020-06-26 20:37:30 by met

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