Hot answers tagged

367

As you can see from the output, you aren’t actually pinging some server in Arizona or even the United States. Apparently, they decided to protect their website with Cloudflare, which employs a content distribution network to even the load. A CDN works with many nodes, each servicing a (geographic) region. That means the node you’re pinging is very close to ...


113

What's the difference between 127.0.0.1 and 0.0.0.0? 127.0.0.1 is the loopback address (also known as localhost). 0.0.0.0 is a non-routable meta-address used to designate an invalid, unknown or non applicable target (a no particular address placeholder). In the context of a route entry, it usually means the default route. In the context of ...


94

They are not the same. 127.0.0.1 is part of the 127/8 network which is reserved and points to the same computer. 0.0.0.0 is a special IP address that means different things depending on context. In the Internet Protocol Version 4, the address 0.0.0.0 is a non-routable meta-address used to designate an invalid, unknown or non-applicable target. To ...


82

The Internet is a system of interconnected smaller networks that can reach each other through routing. You could essentially "follow the path" to any server you're directed to, but there are basically endless paths to any destination. If you were to start from your Ethernet connection, you would first hit your home router, then hit your ISP's routers. The ...


79

I think generally routers serve as an access point, DHCP, firewall and switch as an easy solution for people who don't know much about networking No, routers are a separate kind of device from APs and switches. "Router" is not just a generic name – it describes a specific function, routing IP packets between networks. In other words, you're ...


67

The Internet Assigned Numbers Authority (IANA) is a department of ICANN, a nonprofit private American corporation that oversees global IP address allocation, Domain Name System (DNS), well-known ports and other Internet Protocol-related symbols and numbers. On March 1990 they published the document RFC1060 where they listed the well-known ports at that ...


66

The Internet of Things does not absolutely mandate IPv6, but for IoT to be useful or usable IPv6 is very much preferred. IPv4, due to the limited number of addresses available means that not every device can have a public IP. For a cluster of devices to share an Internet connection then they have to share the IP via NAT technologies. If the devices want to ...


63

It's useful to understand what a splitter does. It turns one 8-strand ethernet cable into a what would be, essentially, a pair of sub-standard 4-strand cables that in theory should do Fast Ethernet (100BaseT/TX). Practically this might drop down to 10BaseT speeds, and you need to use a splitter on both ends for it to work. It will take up two ethernet ports ...


60

Please be aware that a system can handle more than 65536 concurrent connections, because they do not necessarily each use a separate port. A TCP connection or UDP flow is defined by the 4-tuple: (source IP address, source port, destination IP address, destination port) So even if you have a web server machine with just a single IP address, and a single ...


52

Why does Qatar use a single IP address when it was given more than 800000 IPs by IANA? At first glance, this doesn't seem to be true – according to WHOIS, 82.148.97.69 is part of a larger "Mobile-Broadband-Pool-No-6" having ~90 addresses. So maybe it's only a slight exaggeration – many mobile ISPs in other countries also put thousands of customers ...


45

The short answer - Yes. It usually works by default. The long answer - Depending on what you are using it for, it may slow down with multiple connections, but that is a bandwidth issue, not an ssh issue.


44

Answer to the question subject: it doesn't. However, Is it conceivable that back in 2009 everyone in Qatar had the same public IP address? I think it is, at least if by "2009" you mean "back in the time of Wikipedia blockade in the news". The wikipedia blockade occurred at 2006, so wikipedia mainly refers to that point of time. Qtel, the state ...


44

On Windows CMD if you put leading zeros on the IP address means octal. It is interpreting 016 as 16 octal and converts it to 14 decimal. You can use octal, decimal or hexadecimal notation as in the following example: 22.101.31.153 (decimal) 026.0145.037.0231 (octal) 0x16.0x65.0xF1.0x99 (hexadecimal)


41

This is a good example of when superuser tries too hard -_-; The answer is simply yes. Yes, you could follow cables from your computer all the way to the ESPN server, following the same path as a HTTP GET packet would take. You would probably have to go underwater at some point depending on your location, and almost certainly have to break in to a ...


40

By definition on a layered model as OSI or TCP/IP each layer works independent and not-aware of the lower layers. When you remove the cable, it's a physical disruption (layer 1), so almost inmediately ethernet (layer 2) detects a loss of signal (if you're on Windows you will see the very dreaded pop-up informing network disconnected) IP (layer 3) and TCP ...


34

Latency is generally independent of bandwidth. Latency, as commonly measured by ping times, is an indication of how long it takes for your system to send data to another computer and to receive its response. Latency is influenced primarily by how far the data must travel—it takes much longer to access a webpage on a server that is halfway around the world ...


27

Yes, and they don't need any magic here, just trivial matching on the TCP packet contents. Even though SSH and TLS (SSL) encrypt their payloads, the protocol headers themselves are still distinguishable and very different from each other. For example, a SSHv2 connection always starts with the client sending SSH-2.0-(client name and version). Similarly, even ...


26

Yes, most likely it was hacked. The tell-tale sign is the range of ports used: all OSes use low ports ( < about 10,000) to listen for incoming connections, and high ports (the remaining ones, but especially those above 30,000) for outgoing connections. Instead, your log displays connections between pairs of high ports, which means no conventional access ...


25

You say this: However I could not get it to work by hooking up from the jack to WAN port. I had to go from the Ethernet jack to LAN port 1 then hook up my computer, Xbox and PS4 in ports 2 through 4. If you are not using the WAN port as your main network connection that then feeds LAN ports 1 through 4—and just using those LAN ports—then you are ...


24

There are many questions which deal with this but here is a crash course on what are called 'Private IP Addresses' as defined in RFC 1918 IP addresses were broken up in to what are called classes as seen here, this is no longer used (replaced with CIDR) but may help to understand different sizes of networks: There are a couple basic distinctions ...


23

Try: ping6 ::1 The result would look like: # ping6 ::1 PING ::1(::1) 56 data bytes 64 bytes from ::1: icmp_seq=1 ttl=64 time=0.040 ms (...) 64 bytes from ::1: icmp_seq=9 ttl=64 time=0.037 ms ^C --- ::1 ping statistics --- 9 packets transmitted, 9 received, 0% packet loss, time 7998ms rtt min/avg/max/mdev = 0.035/0.042/0.055/0.011 ms Ubuntu 14.04.1 ...


22

You can use freely any Private Network Address. http://en.wikipedia.org/wiki/Private_network RANGE 10.0.0.0 -- 10.255.255.255 172.16.0.0 -- 172.31.255.255 192.168.0.0 -- 192.168.255.255 Refer to RFC 1918 for background Keep in mind the Network address and Broadcast Network: Host Address Broadcast Address ...


21

Yes, the easy way to think about it is that subnet masks are always 1s at the start. If a subnet-size-indicator doesn't have 1s at the start of the binary representation, then I would say that the subnet-size-indicator is not a proper “subnet mask,” using modern standards. RFC 1219 states that the earlier RFC 950 permits non-contiguous bits. In fact, RFC ...


20

There's nothing called "address of the local computer". IP addresses bind with network interfaces. If you have 5 LAN/Wifi cards (network adapters) in your computer then you can have 5 IPs for those interfaces. Here what you see is the adapter named "Local Area Connection" with IP address 192.168.1.36, while 127.0.0.1 is the address of the loopback adapter ...


20

Only some programs allow to split processes over the network (some 3D rendering programs, effectively sharing RAM) (See answer of Julian Knight) The problem with internet would be that's too slow (See answer of Spiff) I think the RAM of your desktop won't be hardware compatible, so just placing the RAM strips into your laptop won't work. What you can do: ...


18

The location of DNS servers is irrelevant to network speed. The DNS server informs your system about the IP address of the site you're looking for. After that the DNS is out of the way, the name - IP address correspondence is cached for a period of time and you are connected directly to the IP. If your ping is taking more than 200 ms, the problem lies ...


18

It wraps around going to 0. According to RFC 793: It is essential to remember that the actual sequence number space is finite, though very large. This space ranges from 0 to 2**32 - 1. Since the space is finite, all arithmetic dealing with sequence numbers must be performed modulo 2**32. This unsigned arithmetic ...


18

There is just one IPv4 address per Network/Router that is connected to the Internet. That is not even close to being true. You are seeing things through the eyes of a typical home network user. Think for a minute what you, as a home user with only one public IP address, would do if you want to allow multiple devices using the same transport protocol ...


18

It is 2015 AD, and the whole globe has been wired up. The whole globe? No, one small village ... But seriously: Internet technology fundamentally relies on the principle that the Internet is not a single physical network and that Internet networking can operate on pretty much any conceivable type of physical network. That underlying network doesn't need ...


17

Does the sequence number wrap around and become 0? Yes. All the details can be found in the TCP Specification RFC 793 - Transmission Control Protocol. Sequence Numbers It is essential to remember that the actual sequence number space is finite, though very large. This space ranges from 0 to 232 - 1. Since the space is finite, all arithmetic ...



Only top voted, non community-wiki answers of a minimum length are eligible