IP stands for "Internet Protocol". It is one of the fundamental protocols that powers the internet. IP is how data is able to be routed to the correct destination - your computer is assigned an IP address, and when you need to get data back, that data gets sent to your IP address.

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Changing host file in Ubuntu

I tried to change /etc/hosts to change a local DNS entry, so I can map any website name to any IP, but it isn't working. How can I debug it?
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Scan one or all ports, on UDP or all protocols, to see if I'm getting, what I suppose to get

I have a GPS localizer (TK102). I've set it up to send responses over GPRS to particular IP and over particular port. I was told that, it uses UDP. It seems that something is being sent (paid ...
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3k views

How to use traceroute command in unix

how to determine if the server is slow or not with traceroute unix command . Here is the traceroute Out put of a host IP . traceroute 188.165.247.43 traceroute to 188.165.247.43 (188.165.247.43), ...
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483 views

Load Balancer Solution with linux

I need a suggestion to realize a proper solution to this problem: As you can see in the image above, I have 2 application servers that need to talk with and external third party provider over the ...
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5k views

IP of localhost

How does a Linux instance determine its IP address? That is, not the 127.0.0.1. Is this stored in file or does ifconfig somehow calculate it at every invocation? I managed to solve it just to show ...
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Changing the IP Address in Solaris 11

I am trying to change the IP address in Solaris, but am failing to do so. The IP address needs to be a fixed number, like 10.0.11.10 I have tried changing the IP address in /etc/hosts which I ...
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302 views

Route incoming network requests for a given port to different applications

I have an application that listens for connections on a port, but I occasionally take it down for updates and the like. I'd like a way to configure the system such that if that program is running, ...
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3k views

Why doesn't Linux use the IANA Ephemeral port range?

According to Wikipedia The Internet Assigned Numbers Authority (IANA) suggests the range 49152 to 65535 for dynamic or private ports. Many Linux kernels use the port range 32768 to 61000. Even ...
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499 views

Books/Resources which explain TCP/IP kernel implementation [closed]

I only know about: 1) Internetworking with TCP/IP: Vol.II, Design, Implementation, and Internals 2) TCP/IP Illustrated, Vol. 2: The Implementation but these are quite dated. I am particularly ...
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151 views

Monitoring interface changes with udev, especially if a route is set

Is there a way to monitor interface up/downs, especially to check if a route is setup or removed, with udev?
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646 views

How to configure Linux to use DHCP or static IP depending on presence/absence of DHCP server?

I would like to configure a network interface to make use of DHCP if a DHCP server is present on the network during boot, but otherwise default to some default static IP address.
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How can I restart a network interface?

How can I restart a network interface? I have a vm that doesn't update its IP address correctly when switching between home and work. The vm runs Ubuntu server and uses a bridged network adapter.
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984 views

Changing DD-WRT's default IP address

I have Buffalo WZR-HP-G300NH wireless router and I updated the firmware to DD-WRT (the newest build). The rest of my home network is in IP scope of 192.168.0.100-200 and this router has it's own. The ...
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411 views

Control source address for whois queries

is it possible to execute the command "whois" and choose the outgoing ip for the query? I have mounted several IP's on my network interface "/etc/network/interfaces" for ssl porpuses, but would be ...
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6answers
615 views

Find my computer on a LAN network

Let's say that I have a computer plugged in to a local network using a dhcp connection, so it will get a different IP every time. Is there a way to find this computer (so the IP) from a different ...
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132 views

need to my server's ip changes when it needs to connect port 'x' on ip 'y'

simple question: "need a way to proxify a port" I have a linux server and have a proxy server on another machine. My linux server needs connect to port 'x' on ip 'y' Is it possible to create ...
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246 views

Constantly pinging a server

I am not sure if this is exactly the right place for this question, but there is no networking stack exchange. I want to ping a server a bunch of times (eg.10,000+) to gather information on the ...
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54 views

Do IPTABLE rules apply to other devices on a network?

I have an embedded device that listens to a specific port to be programmed by vendor specific software. If I have a network that consists of a small linux computer and this industrial device would ...
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5k views

Find out network traffic per IP

We have one central server which functions as an internet gateway. This server is connected to the internet, and using iptables we forward traffic and share the internet connection among all computers ...
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282 views

dig returns different IP address when dropping the “www.” from domain name

I have performed a dig on my domain name used on my site and I seem to be getting different results when I drop the "www." from the lookup. I am concerned this is causing me issues within my ...
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2answers
263 views

Ethernet Sniffing Embeded Device

I recently dug out some prototyping equipment from the trash and I want out figure out what the heck it is. It has a port labelled 'Ethernet' and when I plug it into a router the lights flash like its ...
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2answers
536 views

Adding an ip to a routing table

Is there any way I can add an ip to an interface , but interface route gets created on a routing table other than 'main' routing table in linux? For ex: If I add an IP 10.11.20.10/24 to eth0, it ...
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946 views

IP rule for IPv6

When I try to add an IP rule for IPv6 on my Linux system, it errors out: $ ip -6 rule add fwmark 0xfab lookup 0xf RTNETLINK answers: Address family not supported by protocol I checked out the IP ...
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3k views

Centos 6.2 static IP: only getting IPV6 address and need IPV4

I installed a Centos 6.2 min install. I have edited /etc/sysconfig/network-scripts and I have ifcfg-eth0,eth1 I have tried to setup static IPs but I only get IPV6 address back on both adapters and ...
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1k views

How can I get the netmask from an IP address?

How do I get a netmask from the IP address? Is there a command to get it?
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769 views

Routing private network to internet via 2 gateways

I have the current set up for an embedded environment: Embedded Target (192.168.0.200) -----> Virtual Machine (VMWare) (2 NIC's - 192.168.0.2 (Target Port) and 192.168.49.69 (NAT Port to host)) ...
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Usb tethering with linux and htc desire s other than rndis_host

I want to share the connection of my htc desire s with linux and I'm doing it but if it is possibile I'd like to avoid using the rndis_host module. The tethering can be configured as "windows" or "mac ...
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1answer
204 views

Labeling/Aliasing multiple network addresses

If my machine is connected to several networks and configured with multiple addresses (ipv4), is it wise to configure and use labels to identify them ? By labels I mean the iproute2 ip command's ...
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181 views

IPv6 NDP timer problem

Need to change Fedora Linux's IPv6 stack for NDP DAD timer changes. How to locate the Fedora's IPv6 and IPv4 stack in Fedora distribution dvd/site so that, we can recompile and generate new stack ?
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AIX multihomed multicast

On my AIX machine if I run netstat -ia I get: Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll en0 1500 link#2 1e.18.1.1e.78.2 385229 0 1091655 0 0 ...
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123 views

How to fairly share bandwidth between IPs with tc?

I have a linux router (d-link 320-nru) with tc installed. I have some users' computers to fairly share bandwidth between them. Also there is such complication as inconstant uplink bandwidth. How can ...
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1answer
98 views

Gentoo on VM setting IP Manually

I installed Gentoo on Virtualbox with the minimal image. This is the first time I am running gentoo. I need to do ifconfig eth0 192.168.0.10 route add default gw 192.168.0.1 everytime it boots on ...
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622 views

squid (reverse proxy) configuration

I would like to configure squid in such way, so that only specific (public) ip (reverse proxy), could connect to the server, but I don't know how... can someone tell me how to do this?
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Why are my two virtual machines getting the same IP address?

I have two virtual machines both running on a Linux host (Fedora 16). I set both adapters as attached to NAT. When I boot them up they both have their default gateway set to 10.0.2.2. They also ...
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230 views

Inserting a nat solution into a network while it's not the gateway

I have tried this a few different ways. Currently trying with pf on freebsd 8.2 I am trying to insert a nat solution into an existing network that will redirect traffic from an outside ip address to ...
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2answers
7k views

How can I get the address of my local machine?

I'm on a macbook running Lion. In Terminal I'm connected to my schools server with ssh. I navigated to a folder on the server and have a file I want to copy to my local machine, but I don't know what ...
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1answer
6k views

tcpdump: “packets captured” vs “packets received by filter”

We have a script which calls tcpdump -v src host <IP address> and port <port number> >>out.txt 2>>err.txt -w capture.cap on multiple IP-s while the other parts of the script ...
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1answer
5k views

Static route in Centos 6

Here is my route -n output: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 ...
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1answer
306 views

Should OpenVPN point to point tunnels be on different ports?

The OpenVPN cookbook shows an example for site-to-site VPN (3 sites). They configured each tunnel on a unique port: site A to site B: 1194 site A to site C: 1195 site B to site C: 1196 The author ...
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4answers
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script to scan ip range and return results in a certain format

This script scans IP's and returns a status of Up or Down. How can I alter it so it doesn't scan everything twice? As it sits it scans everything and returns the "Up" addresses only and then scans all ...
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1answer
2k views

Testing if a port was forwarded correctly in Ubuntu

I have a Ubuntu box connected to a wifi router. This wifi router is connected to a d-link adsl modem/router. I am preparing this Ubuntu box to run a server that will use some special ports in UDP and ...
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2answers
3k views

How does SSH connection survive a network restart?

From a Linux SSH shell, type /etc/init.d/network restart to restart the network service. I expect my SSH connection to die since the network service goes down. But it doesn't. Very cool. But how does ...
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What's the last number in this ip address?

An IP address like this 223.248.0.0/24 or 223.248.0.0/16 What's the last number mean in the IP address (24 or 16 in the above example)? Is there a simple way to understand how to set the number ...
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322 views

How can I use one network port for VPN and the other for everything else?

My Linux machine has two network ports with two IP addresses. I want to use one port for my VPN and accounting, and the other port for other usages. How can I tell Linux not to allow any requests from ...
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1answer
327 views

What is the kernel doing when I bring a TUN/TAP interface up

I'm playing around with the TUN/TAP device on Linux. I've created a simple program that creates a TAP interface and prints anything that is sent through it. When I bring the interface up with ip link ...
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271 views

Is it possible assigning an separate LAN IP to service/daemon?

I'm using pfsense for prioritizing traffic around LAN. It works well for specified port, IP, network, but I'm having a problem with torrent (transmission bittorrent) outbound connections. The outbound ...
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iptrace for linux: how can I trace full packet contents?

I normally use iptrace on our AIX servers to get packet traces but have recently found out that this doesn't work for other 'nix systems - namely Centos. Does anyone know what the analog would be? ...
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204 views

How to deny rdesktop access to others?

Someone keeps trying to connect to my Ubuntu machine through remote desktop. Is there any way I can determine who it is, and permanently block access to my machine?
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1answer
670 views

Running vim on a remote Linux machine “freezes” OS X SSH connection

(cross-posted this from SuperUser as the question seems more relevant to this audience) I am attempting to SSH to a Linux (Fedora 14) machine and then open up vim to edit a file, however on my new ...
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How to “grep -v” private/broadcast IPv4 addresses?

time nmap -n -iR 0 -sL | cut -d " " -f 5 | egrep -v "^10.*|^172.[16\-32].*|^192.168.*|^[224\-255].*" > RANDOM-IPS.txt so the important part is: egrep -v ...