I've watched at least five or six videos in an effort to understand this concept and this is the first video that describes what the port actually IS! It's an opening in a firewall designated for certain types of traffic. THANK YOU DAVE!

10 years later, this video is still super useful, it's easy to understand the concept without any strugglings I really appreciate it 🙏

Finally a good explanation. Thank you! Especially for the visuals, I've found I have a hard time understanding stuff if I cannot visualise it.

Really good visual details and instructions. I really appreciated your teaching style!

All these years poking around my various rigs and now that I'm studying for A+ 1001 this made some light bulbs activate. Thank you! 👍🏻

I know this is 9 years old, but you really saved my ass. Thank you.

Finally someone explained it as a whole. Its so easy to understand but others make it more complicated than necessary.

That is a very good ilustration of how TCP Ports and Firewalls work. Thx!

Watched multiple videos. Only one accurate enough. Good Stuff man. Subscribed .

I think you did a very solid job in this video! Thank you! It helped me understand how ports are used a lot better!

finally a really clear and high quality video that makes things very clear for me. thanks

Great explanation, thanks so much for this. The visuals and pacing were perfect

10 year old information and its still useful to this day

Fantastic Dave, very well done, very clear, very practical without getting too technical, and easy to understand, thanks from Suraj, Vadodara, India

Thank you very much! This cleared up a lot of my questions that wasn’t explained well in the book I was reading.

Brilliantly explained! I can use this in my computing lesson ...thank you!

I know very little about internet and I am a non-native speaker, but I am still able to fully understand what you said. You explained everything very clearly. Thank you very much!

this is brilliant, dave. well done! and thank you.

Hey @Dave, This is the great explanation!! Thanks a lot!!👏

Thank you so much for that clear and concise explanation!

That was a great explanation! Now I get why ports are listed as established or Listening.

I really appreciated your teaching style! I hope to watch more.

Wow, you are a incredible teacher! Best regards

this is perfect. your explanation, the way you present difficult concept in simple way. you are really a great teacher

Highly informative. Awesome sir. Thank you❤🍻

great stuff, clean and clear

Just awesome. Many thanks!

Great Explanation. Thanks a lot Sir.

Very well explained, i have always been intrigued as to how ports work and this was a very nice video, thanks for sharing.

I appreciate the visuals, teacher at school only talks and its hard to imagine everything.

Very helpful description - thank you.

Thank you Nigel Mansell!

Very good explanation - many thanks

You made it simple. Thx a lot

Very understanding video. Thank you!

easy to follow and thorough explanation, thank you!

Thank you, this helped me get a better picture of the use of IP addresses and ports, hopefully it helps me write better backend code in the future 🙏🏽

Very clear explanation! hope u make more videos. Thanks!

Great video, thank you!

Great video, very clear...thanks!

Really great vid. Appreciated it!

Thank you for this beautiful explanation.

Great useful video! The pictures helped in understanding.

This video is amazing! Thank you!

nice one. thanks. i found your explanation very helpful

So good, so nicely explained...thank you...looking forward to more videos

Really good explanation, finally I understand what happens ;)

Thank you. this really helped me out.

Thank you. Great explanation. I wish I could give you 2 thumbs up...

Great video! Perhaps one detail mussed is that port 80 is the default HTTP port. HTTP is a protocol which can use any port number. There should be a service listening on that port in the server.

Thanks for that clear explanation.

amazing explanation! clear!

Very useful , simple and good explanation . Thank you sir .

Wonderful explanation!

Crystal clear man

Thanks mate, that was quite helpful..

Awesome Explanation...very clear

Great explanation!

Great tutorial and it helped me a lot. Thanks......................................

perfect!!!! thanks a million

Quality explanation. Kudos to you sir

beautifully explained- thank you sir

best explanation ty teacher diagram made me to understand the concept so good tyyy

ur video is helpfull so far !!

awesome and visible!

Nice video Dave. Have been looking for a video on Ports and IP Addressing and did not find any good ones.

ports are holes in firewalls...great explaination

very nicely explained!

That was great bro, Thanks

Many many thanks.

nicely explained!

Thank You, Sir

cristal clear , thank you so much Sir

Great! But what port Fred is using to send data back to John? Is it a random one?

Very well explained

very well explained.

thank you

you helped me so much

Thanks!

Hi! Awesome video! Thanks a lot. I would like to ask something: So you said port 80 is for http protocol and 110 is for POP protocol. So whey doesn't John uses those instead of 1000 and 1100 respectively?

@davecrabbe4579

7 жыл бұрын

See a few comments above.. 80 & 110 are the "well known port numbers" and used by SERVICES (server), not by clients.

very helpful thanks

Can you share more of your lectures ?

High quality content

Thank You

Thank you for the video. If a firewall generally allows outgoing traffic, will it allow spyware to send out info if the spyware was installed before the fire wall? does spyware create its own special ports?

@davecrabbe4579

7 жыл бұрын

yup.. that is why if you have a trojan on your computer. It makes an 'outgoing' connection to a hacker site and they can then find their way back into through the firewall to control your machine, because it is now 'solicited' traffic. (Basically, that is true.. some firewalls now attempt to look into the message further to see what is happening and potentially block it)

Thanks man

sir you nailed it

Thank you

This is great, but how does a local OS firewall know what to allow back into the client? does the firewall open an outgoing port automatically in stateful manner and allows the local OS to listen on that port?

Well explained.

nice one!

Thank you sir

Thanks for the video. What limitations does the max number of allowed port numbers set for the system? Does it set max number of processes allowed to run at a time?

@davecrabbe4579

5 жыл бұрын

I'm not sure I understand the question. There are 65000 ports available. No limitations for the system.

Hi! I understood the port concept! But I need a small clarification, when we open a web browser and an e-mail on our desktop, on what ports does the data move out, is it something like what I have read on different books, our desktop randomly chooses a port number from 1024 to 65535 and send the data out, but while coming back the data actually goes to the designated port? Is it like this? Or have I gone wrong somewhere? Please clarify.

@davecrabbe4579

7 жыл бұрын

you open a web browser.. you request a page using a packet. The packet sent out has a Destination port address of 80 because it is going to a web service.. the packet has a Source port address of.. say.. 48000. The firewall on the web server allows Destination port 80 traffic so the packet passes. The Destination port address of 80 routes the packet to the Web service. The web service sees this comes from port 48000 so the return traffic from the web server has a Source port address of 80 and a Destination port address of 48000.. The packet enters the client machine and the software see.. ahh.. this has a destination port address of 48000 and I know that the browser which is open has registered that port.. so I'm going to send the packet to the browser application

Nice explanation. Do you have any videos regarding the TCP/IP and TLS protocols? Or source recommendation where I could read more about these topics? I have some basic knowledge of how they work but not quite sure if it's correct.

@davecrabbe4579

Жыл бұрын

Look on my playlist "Networking". All stuff I have on TCP is there.

great

Thanks alot i 've a clear answer to my doubts now

Sorry how is a protocol a service or an application? because you've mentioned that a port number is used to identify a service or an application, right?

@davecrabbe4579

7 жыл бұрын

a protocol is a set of rules that accomplishes some task. A protocol may use a certain port to complete its task as it communicates between two devices. The HTTP protocol defines the use of port 80 for Servers. So the Service part of the client-server pair uses the 'well-known' port address. There is a destination port address and a source port address in most IPv4 connections. A web server will use port 80. The client that requests an HTTP connection can use any random port above 1000.

Dear Sir, I need some clarification regarding ports number used. why did u used 1000 for web and 1100 for email instead of their own 80/443 and 23 respectively. looking forward for clarification. thanks for being so informative.

@davecrabbe4579

7 жыл бұрын

There are source ports and destination ports in every 'message' that gets sent.. The SERVICES (like the web server) use port 80. The client that requests a web page uses its port address of 1000 (or some high port number). So the client sends an HTTP request with a DESTINATION port address of 80 .. this goes TO the web server. The SOURCE port address in that message is some high port number that can be relatively random as it comes from the client. All server services need to use port numbers that are known to everyone; so that everyone can send them messages. Clients don't need to use a public number, they just pick a high port number.

At 0:28, did you mean IP adress or Port number?