Server Fault Stack Exchange
Server Fault Stack Exchange

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
125
votes
4 answers

How to check if a port is blocked on a Windows machine?

On the Windows platform, what native options to I have to check if a port (3306, for example) on my local machine (as in localhost), is being blocked?
Boris Pavlović
  • 1,363
  • 2
  • 9
  • 8
118
votes
9 answers

How much network latency is "typical" for east - west coast USA?

At the moment we're trying to decide whether to move our datacenter from the west coast to the east coast. However, I am seeing some disturbing latency numbers from my west coast location to the east coast. Here's a sample result, retrieving a small…
Jeff Atwood
  • 13,104
  • 20
  • 75
  • 92
113
votes
5 answers

What is this IP address: 169.254.169.254?

I have always noticed an IP something "169.254.x.x" in my routing table even when I am not connected to any network in my Windows operating system. In Linux, when I list my routing table. $ ip route show I get an entry like 169.254.0.0/16 dev eth0…
pradeepchhetri
  • 2,698
  • 6
  • 37
  • 47
106
votes
16 answers

How do I find if there is a rogue DHCP server on my Network?

What's the best approach towards determining if I have a rogue DHCP server inside my network? I'm wondering how most admins approach these kinds of problems. I found DHCP Probe through searching, and thought about trying it out. Has anyone had…
l0c0b0x
  • 11,867
  • 7
  • 47
  • 76
105
votes
6 answers

Is X.Y.Z.0 a valid IP address?

Are IP addresses with a 0 in the last octet valid? 10.6.43.0 In my case, I have the the following netmask 255.255.252.0 What about a 0 for the other octets?
Alan H
  • 2,284
  • 4
  • 20
  • 17
102
votes
15 answers

ssh tunnel refusing connections with "channel 2: open failed"

All of a sudden (read: without changing any parameters) my netbsd virtualmachine started acting oddly. The symptoms concern ssh tunneling. From my laptop I launch: $ ssh -L 7000:localhost:7000 user@host -N -v Then, in another shell: $ irssi -c…
lorenzog
  • 2,799
  • 3
  • 20
  • 24
98
votes
6 answers

SSHFS mount that survives disconnect

I'm using SSHFS mounts from my laptop to a central server. Obviously, the SSHFS mount is broken after a longer disconnect (eg. during suspend), cause the underlying SSH connection timed out. Is there a way to get SSHFS mounts surviving long lasting…
bene
  • 2,294
  • 2
  • 19
  • 14
92
votes
7 answers

How do I make a connection private on Windows Server 2012 R2

After a restart of one of our servers (a Windows Server 2012 R2), all private connections become public and vice versa (this user had the same problem). Stuff like pinging and iSCSI stopped working, and after some investigation it turned out this…
vgru
  • 1,287
  • 2
  • 17
  • 25
91
votes
6 answers

How to determine the hostname from an IP address in a Windows network?

My LAN has 50 Windows hosts. At the Windows command line I try ping to get the IP address of a running Windows machine. The question is how to get hostname of a specific IP address in the same Windows workgroup? Another question is how to know the…
billyduc
  • 1,617
  • 8
  • 24
  • 26
91
votes
8 answers

What is "anycast" and how is it helpful?

I'd never heard of anycast until a few seconds ago when I read "What are some cool or useful server/networking tricks?". The wikipedia "Anycast" article on it is quite formal and doesn't really evoke a mental picture of how it would be used. Can…
username
  • 4,755
  • 19
  • 55
  • 78
90
votes
17 answers

Should network hardware be set to "autonegotiate" speeds or fixed speeds?

We recently had a little problem with networking where multiple servers would intermittently lose network connectivity in a fairly painful-to-resolve way (required hard reboot). This has been going on for about two weeks, seemingly at random, on…
Jeff Atwood
  • 13,104
  • 20
  • 75
  • 92
89
votes
10 answers

Testing UDP port connectivity

I am trying to test whether I can get to a particular port on a remote server (both of which I have access to) through UDP. Both servers are internet facing. I am using netcat to have a certain port listening. I then use nmap to check for that port…
Lock
  • 1,637
  • 7
  • 26
  • 33
87
votes
5 answers

How to get TX/RX bytes without ifconfig?

Since ifconfig is apparently being deprecated in major Linux distributions, I thought I'd learn something about the ip tool that's supposed to be used instead of ifconfig. And here I ran into a problem: when run on its own, ifconfig shows the…
justinas
  • 1,008
  • 1
  • 8
  • 8
87
votes
3 answers

What happens when you plug two sides of a cable to a single networking device?

What is likely to happen when you plug two ends of a network cable to a single switch/router? Will this create problems on the network, or just be ignored?
lisa1987
  • 881
  • 1
  • 9
  • 17
84
votes
4 answers

How to reload default Mac OSX routing table without rebooting

Greetings, I'm using vpnc for a VPN client. I'm also doing some tricky things with route to make sure I can still access my local network, etc. etc. (the particulars here are not very important). Sometimes I get the routing table so jacked up I get…
Nate Murray
  • 993
  • 1
  • 7
  • 7
1
2
3
…
99 100