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

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Blank screen after grub menu

I just rebooted an Ubuntu Server 10.04. After choosing boot options in the grub menu, though, it just displays a black screen with the blinking white underscore in the upper-left corner. The machine ...
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417 views

tcpdump selective acknowledgements question

I eventually sometimes watch most initial tcp connection attempts like this: tcpdump -nn -Z somepcapuser not src host (12x.x5.109.xxx or 62.75.160.xxx ) and not (port 9001 or 443 or 8080 ) and ...
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1answer
230 views

Terminating multi-mode fiber

I'm looking at the feasibility of terminating multi-mode fiber connections ourselves. We would be using LC connectors. I've done some research and found two different methods. One requires ...
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2answers
192 views

High request time

I've got high execution time of HTTP request (ex. 42KB in 13s). I'm using haproxy to load balance traffic. Static files are server by lighttpd behind varnish accelerator. So... it should be served ...
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4answers
3k views

SuperMicro BMC on OpenSuSE Linux --cannot access from LAN

I have an (old) SMC-001 IPMI device on an (old) X6DVL-EG2 motherboard. My problem is that I cannot access the BMC from LAN. I'm also getting some interesting output from ipmitool. First, the setup. ...
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1answer
390 views

Connections stuck in ESTABLISHED state

On a Debian machine I'm having several connections hanging for about 8 hours: tcp6 0 0 192.168.1.35:56312 88.191.79.XXX:25 ESTABLISHED tcp6 0 0 192.168.1.35:43352 ...
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3answers
3k views

Placing a server in the DMZ vs opening firewall ports

When should you place a server in a DMZ vs opening ports on the firewall and keeping it within the network? I'm referring to active directory servers, IIS servers, and mostly things on a windows based ...
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2answers
93 views

Which Windows Server

I work with a company that has an old server that uses Windows 2000. They really only use this thing as a file server / "always-on" computer. They use quickbooks enterprise, quickbooks POS, UPS, and ...
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5answers
2k views

For remote IT purposes, VPN or WAN?

I work for a small insurance company that only has 2 offices. Right now, if something goes wrong in another office, it's just a short road trip. But... This company is expanding, and will have 4-5 ...
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3answers
137 views

How can be found slow connection reason to database on other computer in local network?

How can be found slow connection reason to database on other computer in local network? We have on our computers + Apache + MySql +Ubuntu. My computer connected to other local network computer. My ...
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1answer
582 views

Random Ubuntu server network disconnects

After installing Ubuntu Server 10.04.1 on a new x86_64 kvm instance (Debian 6.0 hosted) I'm getting -apparently- ramdon disconnects from the server. Read from remote host myserver: Connection ...
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85 views

DHCP v/s Static and Request timedout

If I get a IP of machine from DHCP and ping remote host ; pings break up however if I used the same IP and define statically...Ping go smooth...Weird Issue.... any idea why
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2answers
430 views

Netinstalling CentOS if the gateway is in a different subnet

I have a KVM host (A) running a virtual machine (B). They each have their own external IP address and the networking is setup using bridging between eth0 and br0 on A. B uses eth0, with A being the ...
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2k views

Redundant OpenVPN connections with advanced Linux routing over an unreliable network

I am currently living in a country that blocks many websites and has unreliable network connections to the outside world. I have two OpenVPN endpoints (say: vpn1 and vpn2) on Linux servers that I use ...
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1answer
2k views

fork: Cannot allocate memory

I'm having some problem with a couple of servers having quite much amount of connections. The servers just hangs for new network connections (although the functionality of load balancing in haproxy ...
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1answer
240 views

What is nicetec-mgmt on port 2557?

I've been looking at wireshark, and have a lot of UDP traffic to port 2557 (from 25322), the port is reportedly used for nicetec-mgmt, does anyone know what this is?
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3answers
661 views

Packets Per Second and Packet Size

Switches are routers are generally benchmarked in packets per second instead data transfer. In particular, Cisco benchmarks packets per second (PPS) at 64-Byte sized packets. For example a switch is ...
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1answer
195 views

How to properly setup a Virtual Network on Hyper-V (Windows 2008 R2) that provides external connectivity to guests

I have a Hyper-V machine with one NIC card. I've set up a Virtual Network and provided connectivity to the guest OSs. The problem is that on restart of the host machine, i start up with no ...
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368 views

Windows 7 PPTP VPN problem

I'm currently using an win 7 as an network server at my home. I've created some shared folders wich can be accessed easily from any pc on my network (win and mac computers) recently I decided to ...
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2answers
88 views

Getting remote ssh access from a remote machine to a machine having private IP

I have to connect via ssh(from remote machine) to a machine which is having private IP.(say 192.168.1.3) I have connected via a wireless router(NETGEAR). Also there are 10 peoples sharing the same ...
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1answer
211 views

Advice on networking career

I need some insights on a networking career. I have a valid CCNA and few months of experience as a Jr. network analyst. My focus is a type of job where I can administer networking/storage hardware and ...
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1answer
266 views

Slow upload to Server 2008 DC, Downloads work as expected

I have a Windows Server 2008 Domain Controller that I run as a do-it-all server. It has a GbE connection to the network and to every machine on the network. Downloads from the server file shares work ...
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1answer
376 views

Options for sending data between two computers over the internet

My problem is fairly simple: I wish to send/receive simple commands between two PCs. The first PC (PC1) runs a program that controls and monitors an alarm system. The seconds PC (PC2) is any PC that ...
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3answers
622 views

Network Sniffing and Hubs

This will likely seem naive to the experts... but it has been on my mind lately. For years I've been using ntop and a cheap 4 port hub to sniff client networks to determine who's doing what -- and ...
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2answers
552 views

How can I monitor network in CentOS .5.5 , my application refuse to read sockets

Hi I have weird problem with one of my applications (servers ), its suddenly starts to read socket and before it written back, the connection is closed this is what I see in my logs. Is there any ...
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3answers
4k views

Number of TX and RX Buffers in Windows Server 2008 R2

I have noticed both broadcom and Intel NICs allow you tune the number of transmit and receive buffers (A Higher number of buffers will cause more memory usage). How do these buffers work: What is ...
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1answer
63 views

Networking - slow and intermittent speeds on broadband

I'm a novice when it comes to networking. I live in a large two storey building that used to be a school and we have an internet connection with BT (british telecoms provider), the connection speed is ...
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2answers
183 views

Why are connections between two units on same switch routed through external gateway?

I have two units (a computer and a nas) connected to the same switch, both with external ips. Why are connections between them routed through the external gateway? Shouldn't the switch route them ...
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3answers
216 views

how do web hosting companies host end users domain and give so many public IPs

I am a Computer Science guy who understands networking very well. But when it comes to Web hosting companies I am clue less. I want to know how do web hosting companies give so many public IPs to so ...
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3answers
236 views

How to prevent Ubuntu from combining networks on 2 NIC server?

I've got a Ubuntu Server 10.10 with 2 network interfaces with a cable plugged into both going to switches on completely different networks with different routers. One network is the 10.1.10.X network ...
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1answer
83 views

What type of VPS stats should I look for?

I have a few websites that average a total of 10,000 uniques a day across my network. I also have a few mobile apps that pull xml data maybe 5,000 calls a day. My sites aren't anything major just a ...
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2answers
1k views

How to route broadcast packets from machine with two network interfaces on same subnet

I run RHEL 5 and have two NICs on one machine connected to the same subnet: eth0 192.168.100.10 eth1 192.168.100.11 My application needs to receive and transmit UDP packets (both unicast ...
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4answers
1k views

Ethernet switch capacity question

We're looking at hooking up 48 small embedded systems with 10/100 Ethernet ports to an Ethernet switch and then have that switch talk to a server upstream via a faster connection. I have a couple of ...
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75 views

Changing IPs for all servers

We are in the process of changing all the IPs of all the servers in our department. I've never done it before so I just need some info on what to expect. We are "hoping" for smooth process. Below are ...
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1answer
653 views

CSF log files Interpretation

I just installed CSF firewall on my server and I have started seeing the following entries in my log file. Can some one help me understanding as to what is happening Thanks Feb 25 10:45:19 li235-57 ...
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5answers
194 views

Network card very slow, only on Windows

This only happens to 1 of my machine, and only when booting into Windows 7. No matter what network card I put in, Windows would default its mode to 10Mbps full duplex. Transfer speed is approximately ...
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1answer
507 views

Daisy-chaining network switches with multiple cables

This might just be the dumbest question you'll ever read, but I digress. Say I have two 100Mbps Ethernet switches with 2 computers on each, connected together by a single cable. This way, the two PCs ...
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3answers
578 views

Discover LAN's IP range, netmask & gateway?

If I am plugged into a network with no DHCP and no reachable 'sample' hosts where I can peek in the configs. how do I discover/guess the network IPs range, netmask? Gateway IP address? P.S. Don't ...
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1answer
589 views

Any ideas why Ettercap filters aren't seeing packet data?

I'm using an Ettercap filter to detect a query response coming back from a particular service on a remote machine. When I see a response from the service, I'm searching through the data in the packet ...
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5answers
18k views

How to list all physically installed Network Cards (Debian)?

My "Dedicated Server" should have two NICs installed but I can only find one. My Question: What other commands and methods are available to test how many network cards are installed on my server ...
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2answers
288 views

Best windows based network monitoring software

I want to know which is best windows based network monitoring tools mainly for monitoring network and control internet access. I want to monitor the bandwidth of internet usage in each machine in ...
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2answers
429 views

best windows based network monitoring software

i want to know which is best windows based network monitoring tools mainly for monitoring network and control internet access. i want to monitor the bandwidth of internet usage in each machine in ...
2
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5answers
406 views

Monitoring network latency

We're having some network issues but were not sure when or where the problem is most affecting users, I'd like to ping a bunch of URLs every few minutes and graph the results. Is there a simple ...
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4answers
383 views

Why is www.example.com better than example.com? [closed]

I remember reading that it is better to use www.example.com instead of example.com on a web server when setting up web sites. Why, exactly, is this the case? I am asking from a network admin POV.
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2answers
1k views

Windows Server 2008 R2 Core has no network adapters on a fresh install [closed]

After the install there is only a Loopback-Pseudo-Interface shown when I execute netsh interface ipv4 show interfaces Do I have to enable the real adapter explicitly or does the server has no ...
0
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1answer
94 views

oracle access on vmware fusion

I'm running snow leopard and I'm doing some development that requires some network knowledge. I've installed vmware fusion 3.0 and I've set up a virtual machine with windows 2003 server. I need to ...
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3answers
2k views

How do I maximize and check my gigabit transfer rate?

I'm trying to maximize my LAN transfer speed. LAN cards and switch are all gigabit on a CAT 6 cable. Modes are set correctly to 1000 full duplex. CentOS server Testing with ftp from both windows ...
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1answer
124 views

Computer Networks Question

Consider the effect of using slow start on a line with a 10-msec round-trip time and no congestion. Assume the maximum segment size is 4KB and the threshold is set to 16KB initially in congestion ...
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2answers
230 views

Apache slows randomly

I got a new dedicated server from singlehop with a 1Gps connection. For about a week the thing was a beast. Everything ran super fast. it is now dirt slow.... My $30/month godaddy vps is faster. I've ...
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Networking up 3 pcs issue

I'm feeling a bit stupid because this seemingly simple task is completely stumping me. I have 3 PCs: Client, Gateway and Server. Client needs to connect via Gateway to Server. Both PCs are ...