Charts

Documentation for charts

Line Chart

Documentation for Line Chart

Bar Chart

Documentation for Bar Chart

Horizontal bar chart

Grouped bar chart

Radar Chart

Documentation for Radar Chart

Polar Area Chart

Documentation for Polar Area Chart

Pie Chart

Documentation for Pie Chart

Doughnut Chart

Documentation for Doughnut Chart

Bubble Chart

Documentation for Bubble Chart

Mixed chart

Original link

Sequence

It is powered by js-sequence, which would turn following code block into rendered diagrams:

Please refer here for syntax explanation.

Flowchart

It is powered by flowchart.js, which would turn following code block into rendered diagrams:

Mermaid

Typora also has integration with mermaid, which supports sequence, flowchart and gantt.

Sequence

see this doc

Use unexported variables

The unexported variables

unexport/i.go

package unexport
var i int
func init() {
    i = 2
}

The new variables points the unexported variables

main.go

package main
import (
    "fmt"
    _ "unsafe"
    _ "unexport"
)
//go:linkname I unexport.i
var I int
func main() {
    fmt.Println(I)
}

Use unexported functions

package main
import (
    "fmt"
    "github.com/alangpierce/go-forceexport"
)
func main() {
    var timeNow func() (int64, int32)
    err := forceexport.GetFunc(&timeNow, "time.now")
    if err != nil {
        // Handle errors if you care about name possibly being invalid.
        fmt.Println(err)
    }
    // Calls the actual time.now function.
    sec, nsec := timeNow()
    fmt.Printf("%v %v", sec, nsec)
}

Tcpdump advanced filters

Original publication: 2007-10-01

Last update: 2016-02-14

Repost from https://blog.wains.be/2007/2007-10-01-tcpdump-advanced-filters/

Introduction

In this article, I will explain how to use tcpdump to:

• know if IP options are set
• find DF packets (packets which we don't want to be fragmented)
• find fragmented packets
• find datagrams with low TTL
• find particular TCP flag combinations
• find datagrams with particular data (here, packets with command MAIL from the SMTP protocol and GET command from HTTP)

Notes

I usually type tcpdump -n -i eth1 -s 1600 before my filter but I won't do that throughout the article. -n prevents DNS lookups, -i specifies the interface and -s specifies the size of the packets (default is 65536 bytes). Be careful if you use -s 0 because depending on the version, you might be capturing 64K or full-lenght packets.

All commands are typed as root.

Feel free to contact me f

Introduction

Using a firewall is as much about making intelligent policy decisions as it is about learning the syntax. Firewalls like iptables are capable of enforcing policies by interpreting rules set by the administrator. However, as an administrator, you need to know what types of rules make sense for your infrastructure.

While other guides focus on the commands needed to get up and running, in this guide, we will discuss some of the decisions you will have to make when implementing a firewall. These choices will affect how your firewall behaves, how locked down your server is, and how it will respond to various conditions that are likely to occur from time to time. We will be using iptables as an example to discuss specifics, but most of the actual decisions will be relevant regardless of the tools used.

Deciding on a Default Policy

When constructing a firewall, one of the fundamental decisions that you must make