Managing and using network connectivity on a unix system

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On a router, what decides if a packet should be forwarded or directed into the router itself?

I'm trying to learn how packet routing works on a linux-based router (OpenWRT in my case) a bit better for setting up a few projects/just-learning. Referencing the below chart, I'll break this into ...
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14 views

No “rwnd” option to “ip route” for managing the receive window?

Context: I'm doing some self-guided studying on TCP Window shaping. The scenario I'm trying to control for are clients which will be pulling down large amounts of data in addition to their normal ...
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6 views

/opt partition not mounting in DD-WRT v24-sp2

I'm facing problems trying to install optware packages on a TP-Link TL-WR841n v8 running DD-WRT v24-sp2 (4MB flash, 32MB RAM). I did the following through telnet: nvram set jffs_mounted=1 nvram set ...
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3answers
38 views

how to automate creating firewall rules?

There is a complex live system - few vlans. In each of them there are linux servers, and on every server there are services. Services connect together - for example service http on host A connect to ...
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2answers
647 views

Realtek drivers prevent detection of eth1 interface?

Here's the situation: I had a working network setup on my Debian box, with two Ethernet interfaces being reported by ifconfig - eth0, and eth1. eth0 is an onboard Realtek NIC, and eth1 is a D-Link ...
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1answer
15 views

Apple Home Sharing on a Linux machine

Is it possible to share a directory with media files to an Apple TV (Gen 2 & 3) using Home Sharing on a Linux machine? I've found some solutions suggesting DAAP but none of them seems to be for ...
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2answers
38 views

Is it possible to have multiple virtual machines with the same (guest) ip on the same host?

What I try to achieve: Multiple virtual machines (virtualbox) on a Debian host which communicate with another server (not with each other or the host). All VMs need to have the same static network ...
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2answers
27 views

nc command's -k option

man page of the nc command has following information -k Forces nc to stay listening for another connection after its current connection is completed. It is an error to use ...
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2answers
6k views

How to set up an Internet Connection in Linux Mint?

My machine has wired Internet connection with Windows 7 OS. In connection properties I see service name : ispone obtain IP address automatically obtain DNS server address automatically How do I ...
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1answer
31 views

Why does scp not show true upload speed?

Every time I'm trying to upload a file using scp on my slow upload connection (~100kb/s), it shows something like : test 27% 2208KB 2.2MB/s 00:02 ETA On the first ...
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1answer
880 views

ping receives no packets, but tcpdump can see them coming in

I'm migrating an old Ubuntu OpenVZ instance (Jaunty) to a new CentOS 6.3 host (using vzdump/vzrestore). Now networking does not work properly. Facts: It works just fine if a setup a new OpenVZ ...
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1answer
2k views

Linux Mint 17, Wifi Slow and Drops Connection, No Ethernet Connection

On a fresh install and updated Linux Mint 17 XFCE, the system cannot maintain an internet connection through wifi, and is unable to connect at all through ethernet. Wifi will work somewhat slowly for ...
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2answers
55 views

How to tar, split, pipe, untar over ssh

I'm copying large files over LAN, and I've noticed that with doing one ssh pipe, I can get around 10MB/s transfer speed. However, if I shoot off four of those at the same time, I get around 40MB/s ...
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1answer
38 views

Can't access my apache server from outside LAN (Raspberry Pi)

I know this question was asked a lot, but unfortunately none of the posts really helped.. I'm trying to set up an Apache server on my Raspberry Pi. I managed to set it up correctly I think, but I ...
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1answer
47 views

Why is my DAD slow?

The last few boots of my Arch Linux, I noticed I had no network access. I'm using a netctl profile to give my adapter a static IPv4 address, which by itself works fine. So I had a look at the logs, ...
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2answers
4k views

D-Link DWM-156 HSPA USB Modem doesn't work with SIM card inserted

I have a D-Link DWM-156 HSPA modem, that I bought just a few days ago. The modem has drivers in its internal storage. There are Debian packages (.deb) for both i386 and amd64, so obviously I installed ...
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1answer
622 views

Network fail on FreeBSD: Ping to router fails, but router believes computer is connected

I have a TP-Link TL-WN851N wireless adapter, which is based on an Atheros device. When I attempt to connect to my WPA2 wireless network, ifconfig wlan0 tells me that the connection is 'associated'. My ...
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19 views

How do you create an ip alias using iproute utils?

While reading the O'Reilley book on Apache Web Server, they gave an example on using ifconfig to set ip aliases on an interface: ifconfig ep0 192.168.123.2 ifconfig ep0 192.168.123.3 alias netmask ...
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1answer
12 views

What is a hotplug event from the interface?

According to Debian Network setup document allow-hotplug <interface_name> stanza in /etc/network/interfaces file starts an interface when the kernel detects a hotplug event from the interface. ...
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1answer
9k views

Good detailed explanation of /etc/network/interfaces syntax?

I understood the very basic concept of how to use /etc/network/interfaces, but all I find online are examples, example after example, which I can copy-paste from. What I miss is an explanation of the ...
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1answer
1k views

Mint 15 on Lenovo G700: wired internet not working (Atheros QCA8172)

Mint 15 doesn't see internet after installing it in dualboot with windows 8 (in Windows internet works well). My network card is Qualcomm Atheros QCA8172 Fast Ethernet (rev 10). What I did: Install ...
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1answer
2k views

Consistent network interface name ubuntu using pci slot

One can set consistent interface naming via mac address by modifying /etc/udev/rules.d/70-persistent-net.rules. Can you establish consistent interface naming by PCI slot number? (I tried but failed) ...
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7answers
39k views

What DNS servers am I using?

How can I check which DNS server am I using (in Linux)? I am using network manager and a wired connection to my university's LAN. (I am trying to find out why my domain doesn't get resolved)
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2answers
811 views

Route wlan0 to openVPN tunnel and rest to eth0

I'm having problems to create route/iptables rules for following configuration: I have an openVPN server (tun type) running on my raspberry machine at home At work i have company pc (behind proxy) ...
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1answer
178 views

Unable to configure eth1 and eth2 properly on Ubuntu

I am completely new to network administration, and so am finding things a bit tough. I have a machine, whose 1 interface I have to set to the subnet 10.0.20.0/24, another to 10.1.0.0/24 and a third to ...
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4answers
19k views

Yum update problems on CentOS 6.5 minimal as VMware guest

INFO: I am using Windows 7 Pro (64bit) with VMware Workstation version 10.0.1 . I am using CentOS(64bit) 6.5 minimal, for the first time. I am running this from my workplace network, which may use a ...
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3answers
57 views

One-liner for getting an IP address of an internal DNS name?

I have an internal DNS name for which I'd like to get the IP address. Is there a nice Bash one-liner I can issue to convert internalip1.mydomain.com into 10.10.10.10?
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1answer
21 views

Connect through different interfaces to the same server

i have two pppoe interfaces - ppp0 and ppp1. I would like to reach the same server on both interface. I added the desired ip address to the route table: route add 10.88.40.13 ppp0 And I could ...
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2answers
687 views

keep losing IP with dhcpcd

I have an Arch Linux install in a VirtualBox VM, and as I'm working all of a sudden, it will lose it's dynamic IP address. When this happens, if I check on the status of the dhcpcd service it says ...
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1answer
838 views

AP randomly gets unreachable for the clients while hostapd is running

I got an old PC running as router which has 3 NIC and 1 wifi PCI card TP-Link L-WN751ND. This box runs Debian Wheezy, hostapd, dhcpd etc. The problem is that AP randomly gets unreachable for the ...
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7answers
16k views

How to get my own IP address and save it to a variable in a shell script?

How can I get my own IP address and save it to a variable in a shell script?
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1answer
580 views

How to set up a “child” proxy that doesn't need a “parent” proxy

I run Linux on a laptop that is sometimes on a corporate network which uses an NTLM proxy server, and thus I have cntlmd running on the laptop as a child proxy to connect to the parent (corporate) ...
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2answers
2k views

Cannot connect to any localhost connections

I'am using Centos 6.5 with latest updates. My problem is that whenever i try to connect to some local service it just hangs for example: wget wget 127.0.0.1 --2014-03-11 12:43:42-- ...
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2answers
19 views

mknfsmnt fails with “System call error number -1”

This system is part of a cluster and the other node mounts the nfs share successfully. This is currently the active node which means it has a secondary service ip address. I think this is related to ...
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0answers
15 views

How can I configure multiple tap interfaces for a single KVM virtual machine

I am trying to setup a VM using Linux KVM for a F5 BIG-IP VE deployment (used in a lab) ...
2
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1answer
39 views

make my Debian laptop switch autoamtically to a backup connection

I have a laptop with Debian OS installed under it. It is initially connected to the internet using an Ethernet cable (via a modem) and I want to automatically switch to a backup wifi connection (which ...
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1answer
17 views

I need dhclient to flush IP address/routes when link goes down

I am running one Ubuntu Server 14.04 with network configuration using /etc/network/interfaces and so ifup/ifdown scripts. I realised that if I configure one interface in DHCP mode, then I unplug the ...
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0answers
9 views

Transport keyboard/mouse events to a keyboard/mouse-less remote host

I want to send keyboard and mouse events from a small ARMv7 computer board to a remote one, which has no keyboard nor mouse. I'm planning to send these events on a locally implemented CAN bus. The ...
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1answer
33 views

How do I run a program without network access? [duplicate]

I am making a program that scrapes information from some web services. I want to test how my program reacts when it can't reach the web service, like if the web service is down or if the local ...
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0answers
14 views

how do I disable the firewall through YaST?

The fine manual states: The Start-Up section defines how your firewall will start. You can either have the firewall start automatically when booting (recommended), or you can set the firewall ...
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1answer
34 views

what is “rfc3442-classless-static-routes” in /etc/dhcp/dhclient.conf

I am trying to debug DHCP on my laptop (I am using dhcping and dhcdump to see what the DHCP server sends back). Following is my /etc/dhcp/dhclient.conf. option rfc3442-classless-static-routes code ...
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1answer
565 views

How to monitor network performance for each application in FreeBSD / PC-BSD?

I'm using a PC-BSD workstation, and I would like to know if there is a way to monitor which app / process is using the network. I use a Mac OS X (Mavericks) laptop, and the "Network" tab in the ...
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5answers
8k views

Cannot delete bridge - “bridge br0 is still up; can't delete it”

I have the same problem as this guy : Bring down and delete bridge interface that's up But that solution does not work for me. I remove all interfaces from the bridge using brctl delif . I then ...
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0answers
34 views

can't connect to remote host with MySQL…firewall problem?

I've granted privileges to thufir for remote access through the shell (correct?), but cannot seem to actually connect. The router firewall has SPI to off. I've disable the IPv6 firewall on the ...
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2answers
82 views

How to print from a given range of ip addresses every class-c with the last octect replaced by an asterisk

example: I have a range from 10.0.100.0 to 10.0.224.0 and I want the output like this: 10.0.100.* 10.0.101.* 10.0.102.* and so on
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2answers
621 views

Command/scripts to check the Reverse DNS Lookup time

I am working on a project in which one master communicates with numbers of slaves. For that it has to make connection with hosts in network. But sometimes it hangs. I think that the reason behind is ...
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2answers
986 views

ping: unknown host with iptables enabled

I can't ping www.google.com. However I can ping the IP address: ping 74.125.237.142 At first, I thought it is a problem with my DNS settings. But I checked my resolv.conf, hosts, and hostname ...
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1answer
15 views

WiFi only connects to my router, not to any other access point

I have a Raspberry Pi 2 with a WiFi USB dongle. I don't know the brand or model, I got it for free with my Xtreamer Mk1 in 2009. My Windows 7 PC installs some generic Realtek RTL8191SU WLAN adapter ...
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0answers
17 views

eth0/usb0 bridge breaks after removal and replacing android phone

I'd like some help with a networking bridge issue I've run into. I'm trying to make a bridge with eth0 and usb0 (my android phone). After running the brctl commands the bridge works wonderfully. But ...
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1answer
37 views

Test for open TCP port in bash script

I want to delay the script execution until a certain server process is ready, which it is once it accepts incoming TCP connections. How do I test if a local TCP port is open (I get a SYN/ACK answer)? ...