Port tunneling on Mac with SSH

Imagine you need to connect from your browser to another computer which has access to an specific service, por example a private control panel. How to do it using SSH on a mac?

Well, lets describe the problem:

I want to access to the Service 192.168.300.12:11801 which can be accesed only from the Server SSH 192.168.200.1. To increase the complexity of the problem, we should use HTTPS to access the Service, ie, the direct URL from Server SSH looks like: https://192.168.300.12:11801/index.html

Well, first we open a terminal and execute the command:

$ sudo ssh -L 443:192.168.300.12:11801 -p 22 -l username -N 192.168.200.1

The command opens a tunnel between our machine on port 443 to machine 192.168.300.12 using the port 11801 through 192.168.200.1. Just what we want. "-p  20" is only the SSH port, "-l username" is clear and "-N" indicates that we will not execute remove commands.

Now, we can simply set up a SOCKS-Proxy going to Mac > Installation > Network > More Options. Select the tab "Proxies" and enable the protocol SOCKS-Proxy. You need only to insert:

• SOCKS-Proxy-Server: 127.0.0.1
• Port: 443

Now, open your favorite browser and write the URL:

https://localhost/index.html

to access to the Service.

Hope help

How normalization between two numbers works

A friend asked me today about how to normalize a range into another one. Well, given a range from A to B we want to convert it to a scale of C to D, where A maps to C and b maps to D, and we want to do it with a linear function. For example, if C=1 and D=5, ie, interval [1,5], that means that A maps 1 and B maps 5.

The following linear equation does exactly what we need

f(x) = 1 + (x-A)*(5-1)/(B-A) 

because

f(A)=1 + (A-A)*(5-1)/(B-A) = 1+0 = 1 

and

f(B)=1 + (B-A)/(B-A)*(5-1) = 1 + 1*(5-1) = 5.

In general, the linear ecuation looks like:

f(x) = C + (x-A)*(D-C)/(B-A)

Easy peasy, isn't it?

Hope help!

NACE PHP Array - Statistical Classification of Economic Activities

The Statistical Classification of Economic Activities in the European Community commonly referred to as NACE, is a European industry standard classification system consisting of a 6 digit code.

Here I leave a PHP array with the categories of the first level. The European comunity give us a plain text file available hier.

A - Agriculture, forestry and fishing  

A1 - Crop and animal production, hunting and related service activities  

A1.1 - Growing of non-perennial crops  

A1.2 - Growing of perennial crops  

A1.3 - Plant propagation  

A1.4 - Animal production  

...

The PHP array version looks like:

public $NACE = array(
"A" => "Agriculture, forestry and fishing",
"A1" => "Crop and animal production, hunting and related service activities",
"A1.1" => "Growing of non-perennial crops",
"A1.2" => "Growing of perennial crops",
"A1.3" => "Plant propagation",
"A1.4" => "Animal production",
"A1.5" => "Mixed farming",
"A1.6" => "Support activities to agriculture and post-harvest crop activities",
"A1.7" => "Hunting, trapping and related service activities",
"A2" => "Forestry and logging",
"A3" => "Fishing and aquaculture",
"B" => "Mining and quarrying",
"B5" => "Mining of coal and lignite",
"B6" => "Extraction of crude petroleum and natural gas",
"B7" => "Mining of metal ores",
"B8" => "Other mining and quarrying",
"B9" => "Mining support service activities",
"C" => "Manufacturing",
"C10" => "Manufacture of food products",
"C11" => "Manufacture of beverages",
"C12" => "Manufacture of tobacco products",
"C13" => "Manufacture of textiles",
"C14" => "Manufacture of wearing apparel",
"C15" => "Manufacture of leather and related products",
"C16" => "Manufacture of wood and of products of wood and cork, except furniture; manufacture of articles of straw and plaiting materials",
"C17" => "Manufacture of paper and paper products",
"C18" => "Printing and reproduction of recorded media",
"C19" => "Manufacture of coke and refined petroleum products",
"C20" => "Manufacture of chemicals and chemical products",
"C21" => "Manufacture of basic pharmaceutical products and pharmaceutical preparations",
"C22" => "Manufacture of rubber and plastic products",
"C23" => "Manufacture of other non-metallic mineral products",
"C24" => "Manufacture of basic metals",
"C25" => "Manufacture of fabricated metal products, except machinery and equipment",
"C26" => "Manufacture of computer, electronic and optical products",
"C27" => "Manufacture of electrical equipment",
"C28" => "Manufacture of machinery and equipment n.e.c.",
"C29" => "Manufacture of motor vehicles, trailers and semi-trailers",
"C30" => "Manufacture of other transport equipment",
"C31" => "Manufacture of furniture",
"C32" => "Other manufacturing",
"C33" => "Repair and installation of machinery and equipment",
"D" => "Electricity, gas, steam and air conditioning supply",
"D35" => "Electricity, gas, steam and air conditioning supply",
"E" => "Water supply; sewerage; waste managment and remediation activities",
"E36" => "Water collection, treatment and supply",
"E37" => "Sewerage",
"E38" => "Waste collection, treatment and disposal activities; materials recovery",
"E39" => "Remediation activities and other waste management services",
"F" => "Construction",
"F41" => "Construction of buildings",
"F42" => "Civil engineering",
"F43" => "Specialised construction activities",
"G" => "Wholesale and retail trade; repair of motor vehicles and motorcycles",
"G45" => "Wholesale and retail trade and repair of motor vehicles and motorcycles",
"G46" => "Wholesale trade, except of motor vehicles and motorcycles",
"G47" => "Retail trade, except of motor vehicles and motorcycles",
"H" => "Transporting and storage",
"H49" => "Land transport and transport via pipelines",
"H50" => "Water transport",
"H51" => "Air transport",
"H52" => "Warehousing and support activities for transportation",
"H53" => "Postal and courier activities",
"I" => "Accommodation and food service activities",
"I55" => "Accommodation",
"I56" => "Food and beverage service activities",
"J" => "Information and communication",
"J58" => "Publishing activities",
"J59" => "Motion picture, video and television programme production, sound recording and music publishing activities",
"J60" => "Programming and broadcasting activities",
"J61" => "Telecommunications",
"J62" => "Computer programming, consultancy and related activities",
"J63" => "Information service activities",
"K" => "Financial and insurance activities",
"K64" => "Financial service activities, except insurance and pension funding",
"K65" => "Insurance, reinsurance and pension funding, except compulsory social security",
"K66" => "Activities auxiliary to financial services and insurance activities",
"L" => "Real estate activities",
"L68" => "Real estate activities",
"M" => "Professional, scientific and technical activities",
"M69" => "Legal and accounting activities",
"M70" => "Activities of head offices; management consultancy activities",
"M71" => "Architectural and engineering activities; technical testing and analysis",
"M72" => "Scientific research and development",
"M73" => "Advertising and market research",
"M74" => "Other professional, scientific and technical activities",
"M75" => "Veterinary activities",
"N" => "Administrative and support service activities",
"N77" => "Rental and leasing activities",
"N78" => "Employment activities",
"N79" => "Travel agency, tour operator and other reservation service and related activities",
"N80" => "Security and investigation activities",
"N81" => "Services to buildings and landscape activities",
"N82" => "Office administrative, office support and other business support activities",
"O" => "Public administration and defence; compulsory social security",
"O84" => "Public administration and defence; compulsory social security",
"P" => "Education",
"P85" => "Education",
"Q" => "Human health and social work activities",
"Q86" => "Human health activities",
"Q87" => "Residential care activities",
"Q88" => "Social work activities without accommodation",
"R" => "Arts, entertainment and recreation",
"R90" => "Creative, arts and entertainment activities",
"R91" => "Libraries, archives, museums and other cultural activities",
"R92" => "Gambling and betting activities",
"R93" => "Sports activities and amusement and recreation activities",
"S" => "Other services activities",
"S94" => "Activities of membership organisations",
"S95" => "Repair of computers and personal and household goods",
"S96" => "Other personal service activities",
"T" => "Activities of households as employers; undifferentiated goods and services producing activities of households for own use",
"T97" => "Activities of households as employers of domestic personnel",
"T98" => "Undifferentiated goods- and services-producing activities of private households for own use",
"U" => "Activities of extraterritorial organisations and bodies",

"U99" => "Activities of extraterritorial organisations and bodies");


Hope help!