Question about ports

Hi, I have a question about ports that I'm a little but confused about. If a router has blocked nearly every port except port 80, 135 and one more, why is it that I can watch stream videos online if they use ports such as 554 etc... I don't understand that.

Thanks for the help

Find more posts tagged with

Save $250 on 2025 certification boot camps from Infosec!

Book now with code EOY2025

Button

Comments

TheFORCE

Robbo777 wrote: »

Hi, I have a question about ports that I'm a little but confused about. If a router has blocked nearly every port except port 80, 135 and one more, why is it that I can watch stream videos online if they use ports such as 554 etc... I don't understand that.

Thanks for the help

Look up port forwarding

TechGuru80

Also...are you talking about the source port...ie the client? Your outgoing request will go on any port it chooses with a destination port of 80 for example.

Robbo777

So if you're clicking on a link for example that will require https of port 554 etc... whatever the case my be, then the computer uses one of the random ports along with port 80 as it's destination? But when do the other ports I just mentioned come into play then? They're block on my router so I was wondering how I am using it when the port has been closed. So does the port just have to be opened on the server side and the client side does not matter unless someone is connecting to you?

Thanks again.

TechGuru80

If you are going to a website, yes that is how it works. Source port of random, destination of 80 on the server.

For Access Control Lists...if you are on a commercial router you can block source ports and destination ports. This allows a lot of granular control. Without seeing the actual config it's hard to nail down a reason but if it's working then it's unlikely to use a destination port of anything blocked.

TechGuru80

For the purpose of Network+ you shouldn't need to know advanced techniques of tunneling and others. Port forwarding might be a decent thing to research but I don't remember that being on Network+...could be wrong but if it is it's going to be very basic.

Simrid

If you're talking about a normal router at home with a built in firewall it will work as when packets get sent through the firewall/router it will make a note to allow packets with the swapped destinaion and source address with a specific port back through even if the security-levels is greater on the return.