Tip on Blog - uTIcARdI

Run Arista VM 4.2.2 and later version on EVE(UNL)

Sun, 08 Dec 2019 00:00:00 +0000

One of my friends did his VXLAN practices, he came to me for help because he was unable to start the Arista instance on EVE-NG.

The Arista vm can be started and stuck at:

Issue

I did a search and found a clue in the Arista forum, the instance began to work after changed the CPU number to 2:

An incompatible issue of xls file

Mon, 02 Dec 2019 00:00:00 +0000

Background

An integration project: exporting a csv file from system A, convert the csv file to xls file, and import the converted file into system B (A 3rd party system).

Environment:

Python3.7.5
xls library: xlwt1.3
Developing on Mac 10.15.1 with VS Code, and finally the project will be published to a Docker environment(ritht now, it’s Python:3.7.5-alpine3.10).

Issue

The converted xls file, system B doesn’t support it. However, the file can be opened in Microsoft Excel, and then system B supports it after the open operation (did nothing, just open it then close)😫.

Tips for NewZealand

Fri, 25 Oct 2019 00:00:00 +0000

防晒霜 - 安耐晒，遮阳帽，太阳镜
多带两件长袖的衣服
带一身质量不错的西服，衬衣（正装，面试及其它正式场合穿）
考试费贵（因为GST）,所以工作需要的认证建议来之前先考

File name on windows

Fri, 01 Mar 2019 00:00:00 +0000

Error 1

Run a bat (ping.bat) to ping multiple IPs like this:

set testipa=x.x.x.x
echo Checking ping %testipa% (15 times), please don't close current window
echo ping %testipa% (15 times) >> test.log
ping %testipa% -w 500 -n 15 >> test.log

But got the following error:

Checking ping x.x.x.x (15 times), please don't close current window
The process cannot access the file because it is being used by another process.
The process cannot access the file because it is being used by another process.

Post a file to Flask by Curl via API

Wed, 20 Feb 2019 00:00:00 +0000

Curl is widely used in command lines or scripts to transfer data.
Different ways to use curl to post a file to a web server with samples (from both client-side and server: Python-Flask side) will be discussed because it took me a while on the server-side to receiving the data from client.
I would like to add samples of Python-requests, Postman later.

Started with

macOS Mojave
Python 3.7.2
Flask 1.0.2
Flask-RESTful 0.3.7
curl 7.54.0 (x86_64-apple-darwin18.0)

The Flask code:

# Py file name: simple.py
from flask import Flask, request
from flask_restful import Api, Resource, reqparse
import werkzeug

app = Flask(__name__)
api = Api(app)

class kzwebfile(Resource):

 def post(self, filename):
pass

api.add_resource(kzwebfile, '/<string:filename>')

if __name__ == "__main__":
 app.run()

IOS command:IP classless

Sat, 09 Feb 2019 00:00:00 +0000

I wrote down this article in 2009-03-13 when I was looking for my first job. Taking this again today as preparation for CCNP.

Topology:

Topology

Configuration

Configured IP addresses on the routers
Note: The subnets of R1’s Loopback1 and R2’s Loopback1 belong to the class A address.
Execute command “ip classless” on both R1 and R2 (The command has been the default since IOS 11.3)

Hugo-Customization

Wed, 06 Feb 2019 00:00:00 +0000

A list about how I customize Hugo and why I did the change, the post will be updated continuously.

1. fractions

Network Engineer should care about this, because it shows wrong IP/mask format with default value:

fractions with default value

Disable it in config.toml:

[blackfriday]
 fractions = false

2. hrefTargetBlank

This default value of the option is false which means external links(The wording was corrected to “absolute” from ’external’ on Hugo official doc). I prefer to change the value to true.

Hugo-Versioning

Sun, 27 Jan 2019 00:00:00 +0000

Hugo provides the detail instructions about how to deploy it on different environment.

At first, I followed Deployment of Project Pages from /docs folder on master branch, and put all files in one repository.

I continue to check Deployment of Project Pages From Your gh-pages branch after I did some customization on hugo-theme-cleanwhite and want to publish the change to the forked branch.

Instead of the follow Hugo guide, I did some try myself. I searched “change a subfolder to another repository and found the article: Moving Files from one Git Repository to Another, Preserving History but its case is:

Hugo-Images management

Fri, 25 Jan 2019 00:00:00 +0000

I introduced why I migrate my blog to github and Hugo here. Most of articles have been moved to here in 30 days. Next, I just want to talk about something about posts’ images management, versioning, theme customization/something about SEO.

Before start

All images will be compressed before I upload them for the post. Many tools that could do this, such as tinypng, UPNG. My choice is Tinypng because it supports variety formats and its API.

img compression (20M to 5.1M)

Tinypng’s APIs can be called by Python-Requests in this way:

import os
from os import path
import requests
from requests.auth import HTTPBasicAuth

def picopt(root_path, apikey):
 for f in os.listdir(root_path):
 fullurl = os.sep.join([root_path, f])
 if path.isdir(fullurl):
 picopt(fullurl, apikey)
 else:
 if fullurl.endswith(('.DS_Store', '-opt.png', '-opt.jpg', '-opt.jpeg')):
 print('ignore ' + fullurl)
 continue
 print('processing ' + fullurl)

 with open(fullurl, 'rb') as imgf:
 content = imgf.read()
 res = requests.post(
 auth=HTTPBasicAuth("api:%s" %(apikey), ''), url='https://api.tinify.com/shrink', data=content)
 print(res.json())
 optimgurl = res.json()['output']['url']
 # print(optimgurl)
 res = requests.get(
 auth=HTTPBasicAuth("api:%s" %(apikey), ''), url=optimgurl)

 filename, filetypestr = fullurl.rsplit('.', 1)
 optfullurl = '-opt.'.join([filename, filetypestr])
 with open(optfullurl, 'wb') as fd:
 for chunk in res.iter_content(chunk_size=128):
 fd.write(chunk)
 print('optimized img file: ' + fullurl)

if __name__ == "__main__":
 devkey = ''
 postimgsfolder = ''
 picopt(postimgsfolder, devkey)

Python operator: double start(**)

Fri, 21 Dec 2018 00:00:00 +0000

Here is the data:

testdata = {
 'a' : 1,
 'b': 2
}

There are two ways to pass the data to a function

Passing the data to the function

def loop(data):
 for key, value in data.items():
 print(key, value)

loop(testdata)

Passing the data with operator: **

def loopStar(**kwargs):
 for key, value in kwargs.items():
 print(key, value)

loopStar(**testdata)

IPSec Over Palo Alto FW Static NAT

Wed, 19 Dec 2018 00:00:00 +0000

It took me about 2 hours on the following scenario and the root cause was located: lacking a static route on Palo Alto, so I decided to summarize every step here for further reference. Here is the topology on EVE-NG:

Topology

The left part is the office, and the right part is Internet
10.0.56.5 of R6 was NATed to IP: 10.0.17.3 by Palo Alto which establishes IPSec tunnel with R8: 10.0.78.8
Traffic from 5.5.5.0/24 to 8.8.8.0/24 will be forward over the #1 IPSec
All device in ‘LAN’ could access ‘Internet’ via Port Translation

1. Initial Palo Alto

Console access Palo Alto with username/password: admin/admin, and configure MGMT IP 172.16.185.132 (I have bridged the MGMT interface of Palo Alto to my laptop). Here are the commands for the initialization:

Monitor network connections based on Process

Fri, 21 Sep 2018 00:00:00 +0000

Wireshark is widely used in packets capturing with flexible filters, but for some particular cases, end users care about the network sessions which established by a specific application.

I will show how to check the sessions of ‘Microsoft OneNote’.

Windows

Microsoft provides its own product for packets capturing: Microsoft Network Monitor.

Lunch ‘Microsoft Network Monitor’ before you run OneNote:

nm-1

You will see the processes from the left panel, All related network sessions will shown in the ‘frame summary’ window once OneNote lunched:

tc-How it work on different IPs

Fri, 22 Sep 2017 00:00:00 +0000

#!/bin/bash
interface=eth0
ip1=192.168.1.1
ip2=172.16.1.1
delay1=100ms
delay2=200ms
tc qdisc add dev $interface root handle 1: prio
tc qdisc add dev $interface parent 1:1 netem delay $delay1 10ms 25%
tc filter add dev $interface parent 1: protocol ip prio 1 u32 match ip dst $ip1 flowid 1:1
tc qdisc add dev $interface parent 1:2 netem delay $delay2 10ms 25%
tc filter add dev $interface parent 1: protocol ip prio 2 u32 match ip dst $ip2 flowid 1:2

Run NX-OSv 9000 on EVE(UNL)

Sun, 08 Jan 2017 00:00:00 +0000

Refer to how to add NX-OXv 9000 to GNS3

1. Download image files

Here is the NX-OSv9k image file from Cisco (nxosv-final.7.0.3.I5.1.qcow2). Please note that you must have a service contract with Cisco in order to download it.

No I can’t provide the image to anyone.

2. Copy image to eve(UNL)

change file name to ‘hda.qcow2’

copy source file to ‘/opt/unetlab/addons/qemu/nxosv9k-7.0.3.I5.1’

run

/opt/unetlab/wrappers/unl_wrapper -a fixpermissions

3. Add a New node for nxosv9k

Copy the php file to ‘/opt/unetlab/html/templates/’

Run Ansible on Windows

Tue, 29 Nov 2016 00:00:00 +0000

Background:

Here is a topology about the environment for performance testing, let’s name the servers 1st:

1 windows server as the License/Workspace server
5 windows servers as the Network Server
5 windows servers as the Automation server

Topo

It took us a lot of time to deploy the product and collect logs on all of these servers.

Loop a dict to update the keys

Thu, 21 Jul 2016 00:00:00 +0000

Source dict:

{'keyA': '', 'keyB': ''}

Expected dict:

{‘keyA/'keyA' :’’, keyA/keyB’ : ‘’}

Code1:

keyPrefix = 'keyA'
for key, value in Dict.items():
    newkey = '/'.join([keyPrefix, key])
    Dict[newkey] = Dict.pop(key)

Code2:

keyPrefix = 'keyA'
for key, value in Dict.keys():
    newkey = '/'.join([keyPrefix, key])
    Dict[newkey] = Dict.pop(key)

Result of code1/code2 is:

{'keyA/keyA/keyB' : '', 'keyA/keyA/keyA': ''}

It doesn’t work as expected, and I found the case only exists when prefix is the same to a key of the dict which means code1/code2 works well when the keyPrefix is neither ‘keyA’ nor ‘beyB’.

Python多版本, Sublime Text, Anaconda指北

Tue, 07 Jun 2016 00:00:00 +0000

介绍

Sublime text是一款很好用的文本编辑器，更是一款先进的代码编辑器，支持通过插件进行功能扩展。在使用过UltraEditor, Notepad++, vim等等编辑器后，感觉sublime text最好用 (Update @ 2019-02-07: 目前由Sublimetext转移至MS VSCode)。

SNMP simulator installation guide

Wed, 13 Nov 2013 00:00:00 +0000

About SNMP Simulator

The the SNMP Simulator software is intended for testing SNMP Managers against a large number of SNMP Agents that represent a potentially very large network populated with different kinds of SNMP-capable devices.

Refers to its project page for more info.

Why?

With SNMP simulator you can simulate a device by the output of SNMPwalk without considering MIB files.

This article is about how to install SNMP Simulator.

Install Python

Configuring SSH public key authentication on Cisco IOS Device

Fri, 08 Nov 2013 00:00:00 +0000

SSH public Key types:

RSA key use with SSH1 and SSH2 protocol
DSA key use with SSH2 protocol

Note: DSA is weak than RSA

The Key pairs:

Public key: SSH.com使用的RFC 4716指定的公钥格式，而OpenSSH使用了另外的格式
Private Key: SSH v1私钥只有一种标准格式，但SSH v2私钥格式很多，OpenSSH、ssh.com、puty、winscp格式不同且不兼容

Generate the Key

SecureCRT

SecureCRT-PublicKey-1

SecureCRT-PublicKey-2

SecureCRT-PublicKey-3

密钥类型有两种: DSA、RSA. Secure CRT提示多种服务器不支持RSA, Cisco IOS supports RSA only.

SecureCRT-PublicKey-4

通行短语为对私钥加密的密码，注释为提示输入密码时的提示，两项均为可为空

SecureCRT-PublicKey-5

SecureCRT-PublicKey-6

SecureCRT-PublicKey-7

为了更好的兼容性和适用性，OpenSSH format is prefered，Choose the location to save the key files：

SecureCRT-PublicKey-8

点击’Finish’后会弹出对话框：

SecureCRT-PublicKey-9

如果选择’Yes’,会影响’快速连接’中的公钥指向保存的文件:

SecureCRT-PublicKey-10

Open LDAP and SSH Public key

Fri, 08 Nov 2013 00:00:00 +0000

The article is about how I setup Open LDAP on CentOS6 for SSH public key authentication.

1.Download and install CentOS6.2

CentOS-6.xx-i366-minimal.iso

2. CentOS configuration

Network: IP address, DNS, and restart network service

vi /etc/resolv.conf/DNS
vi /etc/sysconfig/network-scripts/ifcfg-eth0/NIC IP
vi /etc/networks//Route
/etc/init.d/network restart

configure host file
```
vi /etc/hosts
```
Modify 127.0.0.1 item to FQDN format because openldap get dc from the item automatically.
```
127.0.0.1 ldap.kzblog.com
```
Stop security services
```
setenforce permissive
getenforce
service iptables stop
```
Note: This only for the testing environment.