Managing and using network connectivity on a unix system

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18
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2answers
1k views

Is it possible to connect to TCP port 0?

Listening to TCP port 0 allocates me a free port number on the system. But what happens when I try to connect to TCP port 0? The obvious answer is: "It doesn't work": $ nc localhost 0 ...
0
votes
1answer
69 views

How can I switch between “wl” and “b43” wifi modules without rebooting?

If I restart my computer with the following in /etc/modprobe.d/blacklist.conf: blacklist b43 blacklist ssb blacklist wl Then I can either modprobe wl (broadcom STA, works well) or modprobe b43 ...
0
votes
1answer
54 views

Debian stuck in Endless DHCPNAK/OFFER loop unless I ask DHCP server to clear expired leases

have a Marvel Kirkwood device running Debian with 3.16 Kernel. On boot, the DHCPClient gets stuck in a loop and never picks up an ip unless I log onto the dhcp server and ask it to dump the expired ...
2
votes
0answers
42 views

debugging iptables when tunneling one VPN through another

I seek to tunnel one SSL VPN (F5, running on my debian laptop==client) through another (OpenVPN, running on a debian linode==server), but lose all client networking (including, e.g., ping) after the ...
0
votes
1answer
27 views

Network card seems to be active but config file is missing?

I have a CentOS 7 virtual machine with an internal network as well as 2 bridged connections, I am unable to find the config file for the third network card. Any ideas where it could be? or what the ...
0
votes
0answers
11 views

how to tell chrony to syncrhonize time with specific server periodically

In Windows, somewhere in settings, I can check "Synchronize with Internet time server" checkbox, add ip-address (say 10.20.30.40) and that's it. How can I do something similar with chrony? I've ...
1
vote
1answer
21 views

State of network loopback

Why the state of lo interface is reported as unknown with cat /sys/class/net/lo/operstate even though ifconfig says it's running?
0
votes
1answer
58 views

No FIOS Network After Zorin 9 Install on Wireless Desktop PC

A friend has a home Verizon FIOS network, connected thusly: Verizon wired/wireless Router > wireless ASUS Windows 7 Desktop PC > wireless HP Windows 8.1 Laptop > wireless HP All-in-One Printer. Note ...
0
votes
0answers
7 views

linuxdcpp crashes Internet

As soon as I start linuxdcpp and connect to an hub, I cannot connect to the Internet anywhere in my Network. But I can upload/download files in linuxdcpp. Any idea what the problem could be?
1
vote
1answer
19 views

difference between “ip link set” and “disconnect / reconnect” in the GUI?

I've got an Ubuntu 14.04 guest installed in virtualbox. Often when the host machine changes networks or is suspended and restarted, the guest VM loses network connectivity. I can reliably get it ...
5
votes
1answer
92 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 ...
2
votes
1answer
34 views

Running command on server, but have the server read/write local files [duplicate]

Is it possible to have a remote machine run a command, but redirect all reads and writes to a local machine. Example: I have a bunch of scripts in folder 'project'. When 'make simulate' is run in ...
0
votes
2answers
74 views

which packages are required to use make?

I try to compile a package on a fresh debian wheezy inside a VM (32bit Kernel): cd /tmp/ wget https://github.com/freifunk-gluon/batman-adv-legacy/archive/master.zip rm -Rf batman-adv-legacy-master ...
0
votes
0answers
14 views

No DHCP OFFERS on several PCs in same network

I have different PCs and 2 of them don't get an IP-address (because they don't get a DHCP-offer) by the ISP, while the others do. I pluged them directly in my cable-modem, one after another. But when ...
0
votes
1answer
46 views

Debian server makes internet connection drop

I have setup a small home server / NAS running Debian 7. The server is connected directly to the router with a static IP set in the router's control panel. There are no port forwarding rules set for ...
0
votes
1answer
76 views

Kubuntu 14.10 Wireless DNS Issue

I'm quite new to using Kubuntu and have run into issues with the wireless connection on Kubuntu 14.10. The wireless connection says that it is connected, and I can ping IP addresses of other devices ...
2
votes
2answers
69 views

Where does Linux store Wifi passwords?

I am going to write a simple replacement for Ubunutu's NetworkManager. Is there any place where the Wifi network passwords would be stored in Linux? I know about ...
0
votes
0answers
21 views

Painfully slow LAN ftp/smb/ssh less than 5kib/s

I have (finally) gotten my home server up and running. After installing/trying dozens of GNU/Linux builds I have landed on Open Media Vault for my main server, Mint 17.1 on my Laptop and I have a ...
0
votes
2answers
37 views

Using network manager and wicd together in Ubuntu?

I'd like to use the first tool for establishing a 3G connection, but the other seems more apt for wifi. Running both together seems like a road to disaster. But how could it stop one completely and ...
1
vote
1answer
125 views

Connect Linux to two networks simultaneously

I want to connect to two networks simultaneously using the Ethernet and in-built WiFi or to two WiFi networks by installing an additional WiFi adapter. My requirement: I have two sets of devices ...
0
votes
0answers
56 views

[Solved]No problem connected by filezilla, but cannot get list when connected by linux CLI client

I built FTP server by VSFTPD, on Raspberry pi, and Inside NAT. Surely set port-forwarding and, it perfectly functional when I connected by filezilla. But, I can't execute LIST(dir) when I connected ...
0
votes
2answers
34 views

Understanding network problem (syslog)

I am running a lubuntu 14.04 server and its always worked well, except for the last couple of days it keeps dropping off the LAN. I am using a couple of powerlink adapters to connect it up as WiFi was ...
2
votes
1answer
37 views

ping works but curl does not [closed]

I am trying to set up networking on my development server running Arch Linux, but something is amiss. I have enabled dhcpcd on all interfaces, and ping now works (including dns resolution), but ...
1
vote
1answer
54 views

Unable to set mac address to tap interface using systemd-networkd

I'm trying to migrate some tap interfaces setup from tunctl to systemd-networkd. I'm using systemd version 215-8. So I have this test.netdev file: [Match] [NetDev] Name=tap_test Kind=tap ...
0
votes
0answers
24 views

nbtscan shows error “Failed to bind: Address already in use”

I am trying to use nbtscan to get a list of PCs in my local network with their NetBIOS names. When using nbtscan with the option "-r", it shows this error: Failed to bind: Address already in use ...
0
votes
0answers
57 views

Automating PPP connection: adding the insertion in routing table of the new interface

I start my USB 3G Modem by: # wvdial And then I must do, in order to acquire internet access: # route add default ppp0 Note that ppp0 is, in this case, the newly created virtual network ...
3
votes
0answers
50 views

tc cbq doesn't work (no traffic limitation)

I've been trying to use cbq weight attributes after HTB failed to do so. I've tried using a command set I've found in an example just to verify it works (HTB works fluently) Here are the commands I ...
2
votes
0answers
73 views

What does `NO-CARRIER` and `DOWN` mean for a wireless interface?

I have a remote server and I log output of certain commands while the server cannot access the internet. It uses a wireless interface to connect to the internet. In a working state the output of ...
2
votes
0answers
54 views

Correctly populating wpa_supplicant.conf from iwlist scan results

I am wondering how I can tell that my wpa_supplicant.conf file is both sufficient and valid. When running iwlist scan outputs ESSID:"wifi" Protocol:IEEE 802.11bgn Mode:Master Frequency:2.412 GHz ...
2
votes
1answer
35 views

How to record network throughput per port for long period of time

I have come across vnstat recently, and am enjoying it's simplicity, low resource usage, and its ability to record network history long term. However, I am looking for a similar tool (for long term ...
0
votes
0answers
46 views

default route of br0 gets dev eth0 instead of dev br0

On my LinuxMint laptop, i have a recurring problem with my bridge br0. On each start up, the default route does not work. The routing table uses eth0 instead of br0 probably because of dhcp. i roam ...
1
vote
1answer
68 views

No Default Gateway route for bond0 / Slave eth* interface gets IP assigned

I have set up a 4-NIC bond on my Debian Wheezy box. After a fresh boot, the system has LAN access, but cannot resolve outside host names or access outside IPs. It seems that this is because the bond0 ...
1
vote
0answers
34 views

Interface doesn't come up in docker run

I'm starting a docker container with my own network configuration: [root@localhost ~]# docker run --net=none --lxc-conf="lxc.network.type=veth" --lxc-conf="lxc.network.ipv4=10.0.0.100/24" ...
0
votes
1answer
26 views

set network manager dns in ubuntu

I have Ubuntu 14.10. When I'm at work I can browse the internet without problems. Now that I'm at home, I can connect, but I'm not able to browse the web. Some informations: the output of ifconfig: ...
1
vote
1answer
32 views

What does the “first Ethernet card” mean in the BSD world?

https://www.freebsd.org/doc/handbook/network-routing.html The designation link#1 refers to the first Ethernet card in the machine. Question: what does the "first Ethernet card" mean? How to ...
-2
votes
2answers
182 views

No longer able to reach the Internet on Kali Linux

I'm running Kali Linux on VirtualBox and trying to learn some of its basics. I know it's based on Debian but I come from Windows so I'm new to Linux and networking in general. My problem is that ...
0
votes
1answer
47 views

two NICs in the same subnet— need to set up routing

I have a tricky case: +---+ +----+ |D1 +->eth0---------<-eth0-+D2 | | | | | | +->eth1---------<-eth1-+ | +---+ ...
2
votes
4answers
222 views

Read the current IP address from the filesystem? [closed]

I'm writing a program that needs to know the system's current IPv4 address (received via DHCP), if it's connected and has one. For the sake of argument, the language is irrelevant and I must read from ...
0
votes
0answers
18 views

run netperf without IP address available

I have DPDK set up, with two NICs taken over by DPDK, i.e. the interfaces are not visible to userspace applications. Now, I need to run netperf/iperf to measure throughput performance of port-to-port ...
0
votes
0answers
21 views

netperf: run with no control connection

Trying to run netperf without setting up a control connection between netperf and netserver: client% netperf -N -H 10.0.0.2 ... netperf: send_omni: connect_data_socket failed: No route to ...
0
votes
1answer
53 views

Why can I connect to the IP of a network interface (on a server with multiple network interfaces) when the network cable is removed?

I have a Server with multiple (four) network interfaces running Arch Linux when I encountered something strange that I cannot explain. I have two interfaces configured to the the ip addresses ...
2
votes
4answers
114 views

Two IPs on one NIC ( network card )

I have a dedicated server with one network card in it. I however got two IP adresses. When I use the simple command sudo ip addr add 188.40.90.88 dev eth0 it fails to see it as a seperate IP. I've ...
0
votes
0answers
16 views

What Linux app will show me how much internet bandwidth each process is using? [duplicate]

Linuxmint 13 Cinnamon 32 bit with ver. 16 backports ethernet (eth0) + pppoe (ppp0) + FTTH (fiber optic to the home) no wifi What program(s) can I use to tell me how much up/down internet traffic ...
1
vote
1answer
17 views

Connect to offline network on second interface

I would think there's likely a dupe of this around but I cannot find it. I have an offline router I'm using to connect a remote wireless device. The router cannot be configured as an access point, ...
1
vote
1answer
52 views

How is /proc/net files getting populated in Linux/Unix?

I'm working on a network monitor for Linux, without packet sniffing. I'm planning to read the network statistics and related data from /proc/net files. I know that /proc is the mount point of process ...
1
vote
1answer
42 views

generate traffic at wire speed

I have x86 based machine with Intel Core2 CPU 6300 1.86GHz and 2G of memory. I'm looking for options to generate traffic on the machine at line rate, or as close as possible. OS is Fedora 20 with ...
0
votes
0answers
93 views

"Error: no device found for connection 'static'. while creating network connection with nmcli

I am using Red Hat Enterprise 7 for on Vmware. I am getting error which creating network connection with nmcli Here is my all steps [root@localhost Desktop]# nmcli con show NAME UUID ...
0
votes
1answer
129 views

Linux tun interface packet routing [closed]

I have questions on the ip packet flow for the following scenario. The scenario is : A tun0 (10.0.0.2/8) interface and a physical wireless lan card wlan0 (ip address not fix) on the client side, ...
2
votes
0answers
94 views

Is Traffic control inside namespace on ports created by OpenvSwitch supported?

I am trying to limit the bandwidth of an interface inside a namespace using tc without much success. Seems it's not supported according to ...
0
votes
3answers
72 views

Setting IP address of choice for a Virtual Box

I've a service running on Amazon AWS which has restriction on inbound connections to my office machine IP address which are like 10.x.x.x When I'm at home, I connect to VPN and my IP address when I ...