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175

The short answer is: some sort of interrupt system. Essentially, they use blocking I/O, meaning they sleep (block) while waiting for new data. The server creates a listening socket and then blocks while waiting for new connections. During this time, the kernel puts the process into an interruptible sleep state and runs other processes. This is an important ...


173

Ports are a concept of UDP and TCP. Ping messages are technically referred to as ICMP Echo Request and ICMP Echo Reply which are part of ICMP. ICMP, TCP, and UDP are "siblings"; they are not based on each other, but are three separate protocols that run on top of IP. Therefore you can not ping a port. What you can do, is use a port scanner like nmap. nmap ...


116

Similar to mpez0's answer, but I like a good car analogy... I'm choosing the UK for this, since that's where I live. Imagine you live in a world where people follow road signs without question, and you happen to live right up in the north of Scotland, about as far from London as you can without crossing water. You live in a small town, and one day you ...


108

There is nothing preventing you from attaching a box configured with someone else's IP address to the internet. However, this won't necessarily cause any issues for anyone else but yourself. If you steal someone else's IP address outside of the subnet that you are physically connected to, the only thing you will accomplish is not being able to receive any ...


90

If you don't want to replace the cable or install a new jack, you have a few of options: Glue it into a coupler or a short extension like one of the following (with the coupler you will need another short run of cable on the other side): Repair it with a zip tie. Use this guide for instructions: ...


62

There's specifically a blackhole prefix in IPV6, as described in RFC 6666, it's 100::/64. IP4 does not have an explicit black hole like that, but a non-existent host on one of the reserved blocks would have that effect. (e.g., 240.0.0.0/4 is "reserved for future use" and will not be routed by anything.)


54

I know who chose these address ranges. Unfortunately, he is dead, so I cannot ask him exactly why he chose them, but I can make some well informed guesses. There isn't much online dating prior to the mid-1990s, when the Internet really started to take off. What history of the Internet exists is mostly in the RFCs which define it, which date back to 1969, at ...


54

"explain to my home broadband supplier that I want a dedicated IP address coming to my house so that people can ping a teapot" just not reference the teapot... they could think you're crazy! By the way: just tell them you want a static ip address. Please Note that in many countries, many ISP don't sell static IPs to consumer-class customers (but asking ...


52

Web server doesn't send "entire website", but documents that browsers request. For example when you access https://www.google.com/ the browser queries server for the document https://www.google.com/. The server processess the request and sends back some HTML code. Then the browser checks what the server has sent. In this case it's HTML webpage, so it ...


46

In 10BASE-T and 100BASE-TX, one pair of wires is used for transmitting, and one for receiving. That is, one pair is the pair the Ethernet host transmits on, and the hub or switch receives on, and the other pair is the pair that the the hub/switch transmits on, and the Ethernet host receives on. If you split the cable with a simple passive splitter, you're ...


43

Try to ping 8.8.8.8, it's Google primary DNS server. I always ping it to verify my connection and I never found it down. Alternatively you can try 8.8.4.4, which is Google secondary DNS.


43

I use Telnet, since its built into lots of platforms with no additional downloads. Just use the telnet command to connect to the port you want to test. If you get the message below, or a message from the service itself, then the port is alive. Minty16 ~ $ telnet localhost 139 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. If you ...


41

HTTP does not care about—and is independent of—any of the lower-level protocols used to transport itself, even though it is itself stateless. The transport technology can be TCP, or Novell’s old SPX, or SCTP, or whatever else you can dream up, and HTTP will still work the same. HTTP does require a streaming or connection-oriented protocol—and depends on ...


32

No. You need to configure so the routers have different IPs. Preferable, you assign 192.168.0.1 to the Virgin router, and 192.168.0.2 to the Sky router. This you do with the Sky router disconnected from the Virgin router, via a wireless client. Also, you need to turn off the DHCP server on the Sky router. Then connect the Sky router from LAN port to LAN port ...


32

No, your router should block incoming access to your LAN just like it would if it was connected directly to the Internet. He may be able to sniff your Internet traffic though (since he's between you and the Internet). Perhaps check out these other SU questions: How much information can my ISP see? What information can my ISP see from my router?


32

There is such a thing as network Black hole. If there are no devices in the network with IP address 192.168.0.10, then this IP address is kind of black hole and it will "discard" all the traffic to it, simply because it does not exist. Protocols which keep track of connection state (TCP) can detect a missing destination host. It will not happen with UDP ...


31

No. Analog telephone modems (a.k.a. POTS - "Plain Old Telephone Service" modems) worked because when the traditional telephone network (a.k.a the PSTN - "Public Switched Telephone Network") digitized the audio, it did so with 8-bit samples 8,000 times per second, for a total of 8 bits * 8 kHz = 64,000 bps digital audio. It wasn't possible to fully utilize ...


31

Can you (temporarily) enable MAC filtering on the Wifi? With that, you should be able to whitelist one MAC at a time and see which one is the culprit. For what it's worth, I would suspect someone is running BitTorrent or something similar.


30

There's a standard protocol for that, called the Spanning Tree Protocol. As the name suggests, it works by building a spanning tree of the network — a subset of the network that includes all nodes but contains no loops — and then disabling any ports that aren't part of the spanning tree. If a link in the spanning tree fails, e.g. if someone unplugs a ...


30

Make a bash script which adds restrictive iptables rule. Put this script in monthly cron. Inside the bash script make a condition - if file ~/do_not_block_friends exists and its modification time is within of month period (stat -c %y filename) - do not run the script. Once they pay you do touch ~/do_not_block_friends. Script will run and see that ...


29

In short, the answer is No First of all, as you have correctly stated you cannot exceed the speed limit set by your ISP. This just won't happen. It is a hardware restriction of the connection you are using, whatever that connection is - fiber, ADSL, DialUp, 3g, 4g, ... A software that claims to overcome the restriction described above is clearly ...


29

Because it made sense at the time? :-D Remember, back when the private IP address ranges were assigned, there were several issues network engineers had to contend with: Some of the most powerful routers at the time had about as much CPU power and RAM storage as today's pocket graphing calculators--and some of the ones today still run circles around ...


28

This is what dig any ejn.nu returns: ejn.nu. 60 IN SOA ejn.nu. root.ejn.nu. 18 604800 86400 2419200 604800 ejn.nu. 60 IN A 217.211.179.99 ejn.nu. 60 IN NS ns2.sudonet.net.ejn.nu. ejn.nu. 60 IN NS ns1.sudonet.net.ejn.nu. ejn.nu. ...


27

The different networking layers are there to allow them to be swapped for different technologies. The two layers you are talking about here are layers 2 and 3. Layer 2 in this scenario is Ethernet - from which MAC addresses arise, and Layer 3 is IP. Ethernet only works at the local level, between network devices connected to a broadcast network ...


27

You could be behind a carrier-grade NAT (CGN) with an "IP address pooling" behavior of "Arbitrary", rather than the recommended behavior of "Paired". See http://tools.ietf.org/html/rfc4787#section-4.1 . Or you could be behind a transparent HTTP proxy that causes similar problems, but only for HTTP.


25

The word might just be "IPv6". It's entirely reasonable for a teapot to have an IPv6 address. The design of IPv6 allows you to have a whole subnet of IPv6 addresses for all devices in your home.


24

I would suspect that they do. I don't believe that text-based browsers will (by default) even download resources such as images or external entities, such as fonts (if needed), scripts, etc. I did some basic testing with tcpdump trying to get this IANA page (http://www.iana.org/domains/reserved) with both lynx and then wget, and here were my results (HTTP ...


23

Q: How do they get that many publicly-routable IPs? Your school could possibly have a static IP address range assigned to them by their Internet Service Provider (ISP), by virtue of the fact that a school district is a fairly large customer (orders of magnitude larger in terms of money than a single family home, to be sure). Note that you can't simply ...


22

The other answers are basically correct, but I thought I'd expand on the topic. Hopefully this information will be useful. As long as you have your router in a standard configuration, it should block unsolicited incoming network connection attempts, essentially acting as a blunt firewall. Port Forwarding Settings which increase your exposure surface would ...


21

Reference Peers: The Peers tab is where you'll find information about all the peers you are currently connected to on the selected torrent. The following is a description of each column: IP displays the peer's IP address and the flag of the country they're from. If Resolve IPs is enabled, the country flag and hostname will be displayed ...



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