regarding IPv4, each IP address can handle a double integer figure of ports, hence 65535.
that is 64000 ports for udp and 64000 pors for tcp. what does this mean? for example if you
have an ip address 10.1.2.3 and you have apache or ssh binded to this address, this means,
you can have a theoratical max of about 64000 concurrent tcp connections to this ip address.
in other words a theoratical maximum of 65535 clients with an established connection to the ip
address. for example, if you are using for example openvpn, you can have a theoratical maximum of
65535 clients connected to that ip address. ok, enough with the repitetion.
65535, that is a very big number when it comes to traffic control but with tweaks, todays hardware
can handle it to an extent, having the ports reserved/used is one thing, diverting traffic in between
is another things. all in all, you would need a powerfull hardware, that is what makes products by
vendors such as cisco niche products that are more capable of handling such dedicated tasks.
in regards to reverse tunneling, here is more of a hands on
## the following command tunnels X sessions and two separate ports 8080 and 10022
ssh -x -2 -L 8080:localhost:8080 -L 10022:localhost:22 root@myhost
## the following maps a the local port 22 to appear as a local port on a remote host as port 22100
## host A listens on port 22 and maps port 22100 on host B
ssh -2 -R 22100:localhost:22
user@reverse.remoteport.net
## the following would connect to the actual port 22 listening host via the local 22100 port
## a connection can be established via the tunnel from B to A with this command
ssh -2 user@localhost -p 22100
## the following would transit a connection ..
## the host C would connect port 22 to host B listenning on port 22100
## so what ever connection is established on host C port 22 is actually pipped all the way to host A
## this would work regardless of NAT along the way.
ssh -2 -L 22:localhost:22100
user@reverse.remoteport.net
rahmu wroteThis message is a fork from the previous conversation that was getting off-topic
here.
rahmu i hate to point out someone wrong , but when you connect the microwave its probably going to get assigned to a local ip like 192.168.0.101 which in turn connects it to the internet gateway . unless in the future microwaves double as routers :P or you wish to get a dedicated IP for the microwave :P
Yeah sure, but the problem with microwaves and other home appliances, is that, if I connect them to the internet, I want to be able to reach them anytime, therefore, ISPs cannot provide me with a DHCP address, I need a static one (like a server).
I like Bash's idea of using ports, though I'm not sure about the figure 65000. After all some ports (1024? if I'm not wrong) are restricted. Then again I'm no networking expert (yet), so it would be great if Bash could explain how to do it, more in details.
