Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 5 years ago.
Improve this question
I am studying networking and operating systems and I stumbled upon this statement:
If there is no default gateway in the routing table we can't transfer packets to all the addresses.
I am asking whether the above statement is correct?
Yes the statement is true. Here is the definition from wikipedia
A default gateway in computer networking is the node that is assumed
to know how to forward packets on to other networks. Typically, in a
TCP/IP network, nodes such as servers, workstations and network
devices each have a defined default route setting, (pointing to the
default gateway), defining where to send packets for IP addresses for
which they can determine no specific route.
A routing table can not store information of all the possible routes to which the computer may connect. So it needs a default mechanism to send traffic to computers for which no known path exists. The way is to route all such packets to default gateway.
Related
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 5 years ago.
Improve this question
Obviously the difference is that one can and one cannot access Netflix. But how does Netflix ban VPNs while not catching VPNs designed specifically to access Netflix?
The main difference is the question of whether Netflix knows about them yet or not.
In time, the VPNs which can access Netflix today will likely end up being blocked by from accessing the service when Netflix's analysis of incoming connections reveals IP addresses which could belong to VPNs used to circumvent their restrictions.
It is possible that some operators of VPN services may make use of IP addresses which are changed periodically to make detection less likely and this is how they may go for an extended period of time without being blocked.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 5 years ago.
Improve this question
I can't wrap my head around routing tables. Is it true that every router has a table with routes to every ip address in the world? Wouldn't that make the tables huge and thus make the lookup slow?
Routers with few interfaces need only few entries - a home router with a single subnet inside and the Internet outside just requires two entries.
Routing is a distributed job, every router only needs to know the routes it's got connected somewhere. Hops more remote to the final destination might only match a very short prefix - the default route with /0, or maybe /8 or /12 specific routes. The closer a hop is to the destination, the more refined (=longer prefix) the route is likely to get, with a prefix of /24, /29 or even /32.
The more interfaces, subnets and thus choices a router has got, the longer the routing table gets. Internet core routers may have many 100,000 to more than a million routing entries (thx Ron). More powerful routers use special, content-addressable memory (TCAM) to enable single-step lookup.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Closed 9 years ago.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Improve this question
Sorry for the language mistakes I've made. I don't have static IP to be accessible from outside world so I want to run a dead simple http server on my dynamic IP which I get from DHCP of my local provider. How can I make it?
I use Ubuntu and similar with nginx. I tried something like this:
~path/to/index.html$ python -m SimpleHTTPServer 80 #of course nothing
Yes you can,
But you must use a proxy like:
DYN DNS
NO-IP
etc.
These sites gives you a link static IP and forwards it to your dynamic IP address.
The IP provider needs to be updated with your current IP.
This is done either via a service on your computer, or via your router (if it supports Dynamic DNS it).
The conclusion is that your current IP address must somehow be connected to a DNS (like www.something.org).
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 9 years ago.
Improve this question
I have recently added a dlink router to my existing network, and connected some computers with it. The existing network uses ip range 192.168.1.x and the new router uses 192.168.0.x. Internet services is accessible on both the networks, but a shared resource or a web server connected to one network is not accessible to the systems of other network.
I googled this issue but I am unable to resolve the issue, please help.
If you are just going to be using the router as a switch on an existing network, you need to turn off its router-y features.
Go onto the web interface of the device and turn of "NAT", that way they'll use the same address space as everything else on the network.
They'll be other features as well you may want to turn off but that's one causing your current issue.
Closed. This question is off-topic. It is not currently accepting answers.
Want to improve this question? Update the question so it's on-topic for Stack Overflow.
Closed 11 years ago.
Improve this question
Say i'm communicating with a computer A in a remote network .
Is it possible to know what are the hops that he is going through?
In other word, is it possible to detect what is computer A route to my computer?
I know that A might have a various routes to my computer , it just want to find a route. My whole problem begins with that fact that some networks "hides" there inside computer ( like NAT ) and just give you the gateway ip.
(I'm not talking about my route to his computer that can be easly achived by traceroute)
thanks!
The IP option Record Route asks routers along the way to include their address in the datagram so the route can be tracked. The trick is, many routers and firewalls are not keen on giving out this information and DROP packets with this option set. And, you'd have to get the remote peer to set the flag, so it would only be useful if you're in control of the software on the remote peer too.