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

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Is it possible to offer failover even using DNS round robin? [closed]

A company X has five ips to a given service. $ host www.example.com.br www.example.com.br has address 13.194.4.159 www.example.com.br has address 13.194.4.152 www.example.com.br has address ...
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42 views

transparent proxy (SSL error)

Right now we are having transparent proxy in our network environment. we have been set proxy settings to browsers in all systems. While accessing the https sites in browsers no issue but few of ...
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4answers
193 views

Communicating via separate network cards

Assume you have a web server with two network cards (and their associated ports), let's call them A and B. The idea is to connect one port (A) to the internet and the other (B) to some isolated ...
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3answers
91 views

KVM guest is unable to access the internet

I have a Debian host that has several allocated IPs and KVM with a Debian guest using a bridged network. The guest is completely unable to reach the network, including the LAN or even the host. ...
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40 views

How do I configure KVM guest to have Internet access?

I am trying to get KVM working on my Debian server and I am having a slight problem with networking with my guest OS (also Debian). The virtual machine is using the "default" network (without a ...
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1answer
48 views

What is “the meaning” of this `ip route`?

I'm slowly learning more about IP routing and the ip toolset by investigating a VPN. After I start a particular VPN client, one of the (new) routes displayed by ip route show is 128.0.0.0/1 via ...
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1answer
66 views

Sending Data extremely slow or RDS

I have the following two profiles for a basic SELECT STATEMENT: select count(*) from mturk_completion; Here are the two profiles: # My Local machine, using a local db Status ...
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3answers
57 views

how to use tcpdump to log only certain data in real time

I'd like to monitor network interfaces but only log things likes errors, collisions and dropped packets. The send that to stdout. – Can tcpdump be configured to do this?
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2answers
48 views

Why I cannot access EC2 instance public IP from inside of instance itself?

Here is an example, I have an Linux instance , say, private IP is 10.10.10.10, public IP is 54.54.54.54. Inside the instance, I could successfully ping it's private IP(10.10.10.10) and localhost. ...
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52 views

Linux route cache seems to load outdated settings

On SLES 11 SP3 (Kernel 3.0.101-0.46) I see the following route behavior: When I set a route specific MTU once via ip route change ... mtu lock 1500, everything works as expected (setting an MTU of ...
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103 views

Hop count : Proper way to count hops : Router count vs Router count +1 [closed]

I am very puzzled and confused about the hop-count definition, especially related to RIP metric. Does hop-count have to reflect link count or router count ? Here are two possibilities : Statement A : ...
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0answers
69 views

Server 2008 R2 NIC in “Unidentified Network” state after connectivity loss is restored

I am having trouble with 2 servers, both with the same symptoms. When they are reconnected to the switch after losing connectivity, they stay in an "unidentified network" state. Only after cycling the ...
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1answer
68 views

Whitebox firewall in datacenter environment

I am looking into alternatives to commercial firewall appliances. Most of the resources available online describe home network firewalls or sub-gigabit networks. Considering than 10GbE is becoming the ...
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2answers
53 views

What would cause ifconfig NIC frame drop counts to increase SLOWLY (90-100 frames per day)?

I have a web appliance running CentOS 5.11. It sees a fair amount of traffic (apologies, I don't have specific numbers but I know it's in use). For some reason, I'm seeing ifconfig error counts ...
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2answers
35 views

Work Network 'Freezing' randomly for 20-30 seconds

I have a network of about 15 PC's set up to a switch which is connected to our modem obviously. For some reason, very randomly, while trying to load a webpage (any webpage, not specific) the network ...
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2answers
75 views

The requested operation requires elevation

We have about 15 PCs on our network. I can make changes to all the PCs except one. I keep getting the message "The requested operation requires elevation". When I try to run a program as an admin, ...
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41 views

Snort even though working properly does not report majority of rules

I have installed Snort 2.9.7.0 and it does not detect majority of attacks, such as nmap port scans, downloading exe files, opening documents containing keyword "root". I use Snort together with ...
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2answers
49 views

Inter VM communication in a single Cloud Service

After spending a good amount of time in the Azure documentation. It seems that there is an inconsistency regarding the ability for VMs in the same cloud service (not in a VNet) to talk to each other. ...
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46 views

Enable Netflow plugin in Ntopng

How can I enable the Netflow plugin in the latest Ntopng (1.2.2). There is no 'Plugins' option in the menus or I can't see it. I have logged in the web interface at port 3000 but there is no Plugins ...
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2answers
39 views

Why can't I see the Printer? [closed]

I have a Small Network set up as follows: Internet>Modem>Router A     Printer     Workstations Dept A     Router B ...
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1answer
36 views

STP fixes non-looped network. Dumb switches kill network. Can anyone decipher this wireshark readout for me?

Greets long story short we had a power outage here and when the network came back online it would crash out to a flood of ARP requests. This would lead to packet storm/network loop, but after ...
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28 views

Alternative ways to track dropped packets and report output

Instead of tailing /var/log/messages or doing a continuous ping is there a way with ifconfig or ethtool to track dropped packets, collisions, or tx/rx errors in real time?
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54 views

How to find out PID of the process sending packets (generating network traffic)?

Couple of weeks ago I had an issue where I changed DNS addresses in large network of around 300 nodes. After that, some of the nodes still continued to ask old DNS servers, although resolv.conf was ...
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68 views

What are the pros and cons of large receive offload (LRO) vs generic receive offload (GRO)

I have been debugging a scenario where an ESX vmware host is communicating with a virtual linux machine via a virtual switch using TCP/IP. After a congestion event the vmware host is waiting for an ...
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45 views

routing a second public IP to multiple VM's

myself and a friend have rented a dedicated server and have used KVM and libvirt to create virtual machines for us to use. (we are using debian jessie on the host) we purchased two additional IP ...
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16 views

Mac minis disconnecting from 1GbE: RFI / EMI?

We have several 2012 Mac minis in our server room that reliably disconnect from 1GbE network (but otherwise appear to still be working) when the adjacent servers are under heavy CPU load. We suspect ...
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2answers
56 views

Enabling bridged connections with a single network card with multiple IP addresses

I have a server with one network card in it (eth1). My server is assigned 5 public IP addresses and it is currently configured like this (/etc/network/interfaces): # The primary network interface ...
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3answers
47 views

Mount a drive at login time

I need to mount a drive at login time. I have the home directories in the server, and when a user logs in at a client machine (debian 7), I need to mount his directory temporally at a mount point, ...
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0answers
47 views

Routing with multiple NICs on debian

I have a machine with two NICs on different network segments, I've set up routing for the different segments. It works if I run all the routing commands manually, but I can't get it to work when ...
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63 views

Port forwarding to different subnet

I have two routers: router A with internet access, and router B acting as wireless access point. Devices are attached to router B via ethernet. I need to forward some ports to PCs attached to router ...
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1answer
105 views

Slow download big static files from nginx

I'm using debian 7 x64 in vmware-esxi virtualization. Max download per client is 1mb/s and nginx no use more than 50mbps together and my question is what may cause so slow transfers? server ...
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1answer
78 views

Concurrent TCP connections on Azure can be upto 500K. Really?

Let me be very clear at the outset that I am new to cloud technology. All I know is cloud servers are easily scalable (i.e. adding physical hardware is transparent to applications and users) and ...
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57 views

Static IP injection to guest VM in Win2k8

Is there a way to inject IP address and do network configuration of a CentOS VM running on Windows server 2008? In Win2k12 there is SetGuestNetworkAdapterConfiguration using which IP address can be ...
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1answer
58 views

How to find which routing protocol a router is using. And if found how to test it

I was recently asked a networking question in an interview which I did answer but the interviewer was not pleased. The question was : "Given an actively running router, how would you know what ...
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1answer
55 views

DNS resolving is slow only when using cURL to fetch data

I have domain 'engine02.prod.qc.offercal.com' in my local bind9. I don't think it's DNS server or TTL issue, because the benchmark is almost always look like this (I tried for 2 minutes using each ...
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2answers
99 views

How to route outbound traffic for a particular destination IP address to GRE Tunnel in CentOS?

Hello I am trying to configure a network like this network diagram :- Well I have to create a GRE Tunnel at my alpha server and route some particular traffic to GRE Tunnel.I want to do the configs ...
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59 views

QEMU/KVM port forwarding issues

I'm trying to access websites hosted on a QEMU/KVM debian virtual machine from a Ubuntu host machine and other PCs/devices on the host machine's network. Later, I'd like to access this from the ...
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1answer
177 views

Mikrotik RB2011U vlanning

I am having trouble getting port based vlanning/trunking working on a Mikrotik RB2011U. I have been following the guide located here: ...
3
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1answer
56 views

Forwarding a port on the loopback interface to a remote IP/port

I have two Docker containers that I'm trying to network together in a specific way. Container A is running a Redis server on port 6379. Container B is running an interactive shell and needs to access ...
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2answers
128 views

Apache 500 error with no entries in error.log [duplicate]

This is on a brand new Ubuntu 14.04 Server running a standard WAMP install with Apache DAV_SVN (using LDAP Authentication) added on top of it (mapped to /svn). I was able to get everything working ...
0
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1answer
22 views

dnsmasq to server different ip depending on which NS is used

I want to simulate the following situation: If the client makes a request using NS1 for DOMAIN1 return IP1 If the client makes a request using NS2 for DOMAIN1 return IP2 i.e resolve the domain to a ...
0
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1answer
34 views

Connecting to web server through eth1

So I am having issues with connecting to my web server via eth1. ifconfig eth0 Link encap:Ethernet HWaddr 00:50:c2:27:bf:6e inet addr:10.8.105.8 Bcast:0.0.0.0 Mask:255.255.0.0 UP ...
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1answer
30 views

accessing ip_conntrack causes concurrency problems after yum update

I have a Centos 5.11 server, and a script I cron every 10 minutes The script is simply this #!/bin/sh FNAME=/var/www/html/cached/conntrack_count COUNT=`cat /proc/net/ip_conntrack | /usr/bin/wc -l` ...
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61 views

CoreOs Guest with static IP by config drive

I want to configure a static IP for my CoreOS guest following this tutorial: http://www.chrismoos.com/2014/05/28/coreos-with-cloud-config-on-vmware-esxi While my hostname is set correctly my ip ...
3
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1answer
99 views

2 NICs, same subnet, different default gateways

I have a switch on which 4 modem/routers and 2 servers are connected. Each server has 2 processes running and 2 NICs connected. What I want is that each process is routed out of either one of the ...
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37 views

Capturing specific bi directional IP

I have a Span traffic from one of the sensors something like: 02:59:08.494719 IP 99.233.114.198.54312 > 10.55.50.224.80: Flags [S], seq 2394432243, win 8192, options [mss 1380,nop,wscale ...
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1answer
163 views

Set up network interfaces in Ubuntu for KVM virtual machine

I am currently renting an Ubuntu server. On this machine I would like to run virtual machines using KVM. For some web access I have installed Kimchi, a very simple html5-based KVM management tool. ...
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1answer
25 views

VPN tunnel from client A through relay B to server C

I need to send traffic from a client machine, A, to a VPN server, C, but through a relay host, B. All three of them have public IPv4 addresses, but for policy reasons, A must not send traffic ...
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1answer
21 views

DNS or Hostname - seems to change whether a machine can be accessed or not

So I work on a large environment with multiple countries and a large DNS structure. Because of this we sometimes have issues where machines that have not been on the network for a while keep the ...
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1answer
26 views

How to see routes for a specific Host

I have a project that requires me to send traffic out a specific Port on a Server the server has 7 Ethernet Ports . I have created the IP rules to send data from a certain host to a certain port. I ...