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Questions tagged [networking]

Networking refers to the technologies and techniques that enable the interconnection of devices and applications allowing them to communicate electronically.

Networking refers to the technologies and techniques that enable the interconnection of devices and applications allowing them to communicate electronically.

Originally referring to local-area networks (LANs) designed to allow communication between computers in the same office or university, networking now covers a broad swathe of topics. To name but a handful:

  • small-office/home-office
  • campus/metro area networks (MANs)
  • datacenters
  • wide-area networks (WANs)
  • optical networks
  • telephone networks
  • Voice over IP
  • wireless LAN
  • cellular telephony
15498 questions
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How can I list my open ports on Debian?

What is the command to display a list of open ports on a Debian server? I tried netstat -a | egrep 'Proto|LISTEN' but I would like something more specific that actually lists the port number.
leonel
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How to check the physical status of an ethernet port in Linux?

I want to check if a specified ethX is physically up or down. How do I do that with the command line?
Jader Dias
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How does Windows decide which DNS Server to use when resolving names?

What algorithm does Windows use to decide which DNS Server it will query in order to resolve names? Let's say I have several interfaces, all active, some with no dns server specified, some told to determine it automatically, and some with it…
Artefacto
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what does "***" mean when traceroute

this is the result of my traceroute traceroute 211.140.5.120 1 141.1.31.2 (111.1.31.2) 0.397 ms 0.380 ms 0.366 ms 2 141.1.28.38 (111.1.28.38) 3.999 ms 3.971 ms 3.982 ms 3 142.11.124.193 (112.11.124.133) 1.315 ms 1.533 ms 1.455 ms 4 …
larry
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Docker containers can't resolve DNS on Ubuntu 14.04 Desktop Host

I'm running into a problem with my Docker containers on Ubuntu 14.04 LTS. Docker worked fine for two days, and then suddenly I lost all network connectivity inside my containers. The error output below initially lead me to believe it was because…
Thomas V.
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How to scan local network for SSH-able computers?

I am often on one computer in my house and I would like to SSH to another one, but often don't know the IP address of the one I want to connect to. Is there a way, from the command line, to scan the local network so I can find the computer I want to…
Andrew
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How to PREPEND rules rather than APPEND using iptables?

Pretty basic question: how to PREPEND rules on IPTABLES rather than to APPEND? I have DROP statements at the bottom of my rules. I have a software to add new rules but adding rules after DROP statements isn't good. Every time I want to add a new…
ale
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What is the "slash" after the IP?

In Amazon EC2, where I set "security groups", It says: Source: 0.0.0.0/0 And then it gives an example of: 192.168.2.0/24 What is "/24"? I know what port and IP is.
Alex
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A previous IT worker probably left some backdoors. How can I eliminate them?

I started working for a company that fired a previous IT worker for leaking data. I can only say the following things: We use a Firebird DB with an application written by another company, Proxmox, for virtualization of Windows Server 2008 R2, SQL…
user2265690
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What is the difference between a managed and unmanaged switch?

I've seen some documentation discussing the use of an unmanaged switch. What is the difference in functionality/performance/etc. between an unmanaged and managed switch?
Luke
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How do I delete a route from Linux routing table

This turns out to be harder than I thought. The routes I want to delete are the "!" rejected routes, but I can't seem to formulate the right "route del" command to pull it off. Here is the routing table... Destination Gateway Genmask …
user54259
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How do you document a network?

I'm not sure how to ask this question, since I'm not in the field. Say you're a network admin and you leave your job. How does the new guy know where to start?
Esteban Araya
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Why do ethernet cables have 8 wires?

This might seem a stupid question but why do Ethernet cables have 8 wires? Cat5 cables were just using 4 of the 8 wires, so only 4 are actualy 'needed'. Why not 12 or 16 wires?
ProgrammerAtWork
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Loopback to forwarded Public IP address from local network - Hairpin NAT

This is a Canonical Question about Hairpin NAT (Loopback NAT). The generic form of this question is: We have a network with clients, a server, and a NAT Router. There is port forwarding on the router to the server so some of it's services are…
adopilot
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What is the difference between a public and private subnet in a Amazon VPC?

When I launch a server with a security group that allows all traffic into my private subnet, it displays a warning that it may be open to the world. If it is a private subnet, how can that be?
Developr
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