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

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Network flooded with LLC packet

Recently my network has been slow. From Tcpdump i found lot of frame with protocol LLC. A complete packet capture can been here tcpdump result Any hints on interpreting these packet?
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51 views

Poor large transfers behind NAT on Centos

I have the following set up. A Centos 6.5 VM running on an ESX host, with a public IP4 address. It is acting as a gateway for (a bunch of) other Centos 6.5 VMs that are only connected to a virtual ...
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117 views

Make LXC containers available from the physical network

I've been trying to achieve the following. I want to use LXC as a thin isolation layer inside our physical machines, meaning each machine will have only one container running. For this container, I ...
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166 views

Firewall and NAT settings in GSM modem for one server

I have a GSM Modem (PSI-MODEM-GSM/ETH) in field with one device behind, acting as a server. The situation is as follows: "PC" | \_________Dynamic IP: 10.103.153.122 | ...
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639 views

XenServer IP Failover OVH not working

I have got problem on XenServer with IP FailOver in OVH. I did everything what is in this official tutorial http://help.ovh.co.uk/BridgeClient and IP not working. On my VM is Debian 7 64bit I set MAC ...
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2k views

How to execute a reverse “Powershell shell” using ncat or netcat?

I am using ncat to execute a reverse "cmd" shell from one machine to another and without any issues using the commands: In my machine: ncat -l 443 In the remote machine: ncat <my ip> ...
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83 views

IPv6 and AdvManagedFlag

RA messages have AdvManagedFlag. If this flag is ON then host "should use stateful autoconfiguration to obtain addresses" (RFC 2462). But RA messages are processing by the kernel. How do we know that ...
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89 views

WFS/NFS Shares lagging then crashing client machines

We're running a Windows domain (2008 R2 on 2 DC's) with a Synology Rackstation hooked up with all our shares on. We have about ~100 workstations and 30 phones hooked up to the domain (the phones have ...
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291 views

Linux MIPS box: ICMP (ping) works, but TCP does not - how to fix it?

I'm trying to set up MIPS Linux box network. Here is it's configuration: ~ # ifconfig eth0 Link encap:Ethernet HWaddr CC:5D:4E:FF:45:7F inet addr:192.168.0.2 Bcast:192.168.0.255 ...
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1k views

Proxmox - Port forwarding from Host to Guest

I'll just quickly start by apologising due to my lack of knowledge in Linux networking and I appreciate all the help I'll receive from any patient users willing to help a newbie. I have a Linux ...
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77 views

OpenVPN running on Internet Gateway, so all private clients can access VPN with no config

Our LAN connects to our office gateway machine (192.168.1.1), which is connected to the Internet. I have setup NAT/Masquerading for this purpose with no issue. We also use OpenVPN to connect to our ...
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217 views

Root denied login if networking down (LDAP environment)

I would like to know why I can't login as root (ssh, sudo or su -) when my LDAP is down or when I have some outage in my network. How to reproduce the problem: - Just change your DNS to something ...
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34 views

cascading additional switches good or run wire directly from main switch

We have a network design as shown below. Now my concern is if the additional switches are affecting our network throughput or latency or causing any network collisions. If I run directly 21 lines from ...
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162 views

What could be the cause for outbound TCP/IP traffic beeing blocked while ICMP is still working?

On a Windows Server 2003 there is a strange issue. Every 6 hours the server don't accept outbound TCP/IP traffic while inbound traffic working fine. If the problem occurs I can connect with RDP to ...
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46 views

Server network communication stalls

I'm running SBS 2008 as a file server, SQL server, IIS7 Server, and Exchange server, and very recently I am getting some very confusing stalls on it. During these "stalls," file services will cause ...
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210 views

Simulating a client behind a NAT in Virtual Box

I am trying to simulate a client behind a NAT using Virtual Box. I have a host machine let's say with an IP address 130.0.0.1. I create a virtual machine (let's call it VM1) running Ubuntu 12.04 with ...
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253 views

Connection two subnets behind routers

Task is very peculiar. I ask your help. Do you have any ideas on this subject. We have: 1.First device: |Internet| -> |ASUS RT-N16(firmware dd-wrt) 1| -> |Server base on Ubuntu 1| 2.Second device: ...
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153 views

Accurate modeling with the psping -l parameter?

I'm in the process of setting up a psping job to allow me to test the performance of some new network based applications in my environment. I'm a little hung up on the -l argument for specifying the ...
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296 views

Debian 7 + Hyper-V and random network/DNS problems

Our department is *nix-based exclusively but unfortunately the company we're part of runs on a Windows environment and until I get budget for our own servers I have to run our servers on a Hyper-V ...
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216 views

Separating Secure Network and DMZ (nonsecure) in a PCI Compliant Infrastructure

We are setting up a PCI Compliant infrastructure where most of our applications are running in a DMZ (demilitarised zone) that contain no sensitive information. The part that contains sensitive ...
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468 views

Creating a multi-wan/isp failover router where wan IPs are dynamic on Debian

I'm having an incredibly hard time creating a basic router on Debian which has connections to two ISPs where the ip addresses are dynamic. I don't need bonding, I really just need some way to detect ...
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110 views

SolusVM Ubuntu 13.10 OpenVZ networking issue/bug

I currently have a server running SolusVM and using OpenVZ virtualization. I downloaded the new Ubuntu 13.10 from their official repo http://openvz.org/Download/template/precreated and installed it on ...
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20 views

Routing table taking long time to update for adhoc networks and OLSR

I am using OLSR to implement adhoc network and analyse the throughput.I have olsr working on 3 interconnected computers on adhoc network. I am using jperf to simulate and visualise the data ...
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111 views

Pass a traffic from a specific domain through OpenVPN

I want to pass traffic from a specific domain through openvpn (tun0) and the rest through eth0 How can I configure openvpn to work with eth0? the domain name is set with ddclient to update dynamic ...
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190 views

How can i detect and diagnose local network problems on a multi-server environment?

I'm a software engineer who trying to detect (and solve if possible) weird local networking problems since 2 weeks on multi-server hosting environment. We bought 3 dedicated boxes with 32GB ram 8 ...
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21 views

graceful tunnel remote change

I want to solve a networking problem: Say I have 3 machine A, B, X in a local-network, where user have access to network resource of X's network interface tunX, which is a tunneled interface connects ...
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507 views

Sonicwall NSA 2400 Not switching back to Primary VPN after Failover

We are experiencing an issue with our SonicWall NSA 2400 Firewall. We have a secondary gateway over IPSec setup in the event of a failure of our main ISP (which is unfortunately common). The ...
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86 views

VmWare : listening nat in promiscuous mode

This document describe how NAT in VmWare works. Next picture is from that document. Is there way to configure Virtual Ethernet switch in that way: All packets arrived from nat send to specified ...
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132 views

NFSv3 Asynchronous Write Depends on Block Size?

I am trying to figure out if my NFSv3 deployment is performing SAFE asynchronous writes. I suspect that it is doing strictly synchronous writes, as I am getting poor performance in general. I used ...
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171 views

ssh hangs in Ubuntu MaaS heterogeneous cluster

I have the following issue when using ssh on my local network. I have setup a small cluster of Xeon machines using MAAS. I have installed Ubuntu Server 12.04 on all machines and configured local ...
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108 views

Is there a way to automate testing for a GNS3 network topology?

I'm working on an MPLS backbone topology using GNS3, this topology includes configuration of several networking technologies such as IPv6, BGP, OSPF, IPv6 to IPv4 dynamic tunneling, MPLS based VPNs, ...
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159 views

Apache not responding in amazon ec2

Well this might sound awkward but I facing terrible issue with my Amazon EC2 instance one of the finding I see is that apache is not responding on port 80 which is weird because I can't even find the ...
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86 views

snmpget on IPv6 local address timesout though snmpd is listening on ipv4 and ipv6

I am doing snmpget from a RHEL machine to the localhost. It works for IPv4 and doesn't work for IPv6. # snmpget -v2c -c public udp6:[::1] sysName.0 Timeout: No Response from udp6:[::1]. # snmpget ...
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134 views

Limiting users to logging onto Samba domain only from specific machines

I have Samba setup and running nicely as a primary domain controller with roaming profiles. Currently users can log on to the domain controller from any machine in the network. However, I want to ...
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90 views

BOOTP on Juniper 4200 stack works one one subnet, not another

I have a Juniper Stack that connects vlans 10,11 and 50. 10 is servers, 11 is desktops and 50 management. Bootp is redirecting DHCP requests to a AD box on 10.x just fine for 50 vlan, and worked well ...
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1k views

Losing connection to SQL Server on the same machine?

I've installed our SQL Server driven software on a client's computer. This consists of SQL Server 2008 R2 Express, and using ADO/SQLOLEDB drivers on a brand new Windows 8 64bit machine. The problem ...
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60 views

Latency on intermediate network

For the past week I have noticed that most of the times pages running on my server are very slow. Sometimes they load quickly, but only about 15% of the time. Using an online traceroute tool I have ...
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504 views

Cisco SPA504G phone CDP/LLDP issue

Good morning everyone, Just recently signed up for the site because I'm looking for some help with an issue that's been plaguing me for about a week now. I hope I'm posting in the right place. If ...
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439 views

Services binding to 127.0.0.2, not responding on 127.0.0.1

I have an OpenVZ host and running several services on it (mongodb, bitcoind). I only intend to connect to them locally. They all seem to bind to 127.0.0.2 - the venet interface. When I try to access a ...
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139 views

Cisco Auto Smartports on catalyst 2960-s

I have Cisco Catalyst 2960-s, I want to configure user defined macros on it. I searched a lot in Cisco documentation but its not for beginners :( How to create a user defined macro that runs when a ...
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201 views

IPsec connection established but xl2tpd times out

This may or may not be related to my problem with passing ipsec verify. I have configured L2TP/IPsec VPN on Ubuntu 13.04 following Ubuntu's community documentation and while IPsec connection seems ...
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95 views

Strange DNS behaviour over VPN

We have a small branch with few computers with few computers connected via the Internet to our central building. We don't use site-to-site, but dial-in to the Cisco router (we use ShrewSoft as a ...
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202 views

Always get a Security Error for Internal HTTPS Website

Full disclosure, I asked this question over at Ask Different (http://apple.stackexchange.com/questions/96776/always-get-a-security-error-for-internal-https-website) but didn't get much helpful ...
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268 views

Dell PowerConnect SNMP stack member monitoring

I am looking to monitor a stack of Dell PowerConnect 6248p switches via SNMP. There is a stack of 3 switches that I want to monitor. Due to the stack being 1 logical unit it only has 1 IP, so when ...
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390 views

Windows 2012 to HP Procurve redundancy across multiple switches - multi-switch LACP?

We are looking to have our Windows 2012 server(s) connected to two separate switches, so that if one switch goes down the server(s) can still be accessed on the same IP address from the switch that is ...
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110 views

Why might one host be unable to access the Internet, when it can ping the router and when all other hosts can?

I have a Draytek Vigor 2830n. It's kicking out a 192.168.3.0 LAN. It performs load-balancing across dual-WAN ports, although I've turned off the second WAN to simplify testing. There are many hosts ...
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194 views

How do I completely remove VirtualBox from Server 2008 R2

I'm having network problems since I installed VirtualBox on a Windows Server 2008 R2 64 bits machine. I tested with iperf and the speed suddenly goes to zero for a couple of seconds once every 1 to 3 ...
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34 views

Server dropping all clients at intervals

I administrate large-scale servers for Minecraft: Pocket Edition. For the past couple of months, I have had the issue where at intervals the server will close all active connections to it (VNC and ...
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97 views

Why would I be able unable to access a website from my local network when the site is widely available?

Requests to several websites on Media Temple's Grid Server (shared hosting; more than one account) are timing out for me today. Everything was fine earlier this morning, and for no apparent reason ...
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55 views

802.11n router supporting 802.11n as WAN connection?

I have an existing 802.11n WLAN router with an Ethernet connection as its upstream WAN connection (router A). I would like to get another 802.11n WLAN router (router B) and have it use router A as ...