Managing and using network connectivity on a unix system

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14
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3answers
36k views

Output traffic on different interfaces based on destination port

My question is basically the same as Only allow certain outbound traffic on certain interfaces. I have two interfaces eth1 (10.0.0.2) and wlan0 (192.168.0.2). My default route is for eth1. Let's say ...
98
votes
3answers
64k views

How does reverse SSH tunneling work?

As I understand this, firewalls (assuming default settings) deny all incoming traffic that has no prior corresponding outgoing traffic. Based on Reversing an ssh connection and SSH Tunneling Made ...
10
votes
3answers
5k views

Can't access select https sites on Linux over PPPoE

My internet connection used to be a direct LAN connection to my provider. Back then, everything would load fine on both Windows and Ubuntu (dual boot). However, a while ago they started needing me to ...
40
votes
4answers
76k views

How to make a machine accessible from the LAN using its hostname

Here are details of the machine I want to access using its hostname: $ hostname hostname $ cat /etc/hosts 127.0.0.1 localhost 127.0.1.1 hostname.company.local hostname It's a default Debian 6 ...
31
votes
7answers
10k views

Block network access of a process?

Is it possible to block the (outgoing) network access of a single process?
11
votes
1answer
2k views

Why my ethernet interface is called enp0s10 instead of eth0?

Just that, when I run ifconfig -a I only get lo and enp0s10 interfaces, not the classical eth0 What does enp0s10 means? Why is there no eth0?
24
votes
5answers
21k views

How can I limit the bandwidth used by a process?

I have a CentOS 5.7 server that will be backing up its files nightly. I am concerned that visitors to the various sites that the server hosts will experience degraded performance while the backup is ...
20
votes
6answers
39k views

CentOS no network interface after installation in VirtualBox

I have Ubuntu 12.10 on which i installed virtual box on which I setup centos 6.4 i386. On Ubuntu I have: 3.5.0-17-generic kernal running. On virtual box I install centos 6.4 and everything works ...
31
votes
1answer
36k 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 ...
25
votes
4answers
21k views

How to speed up X over SSH on a slow network connection?

Are there any specific recommendations on speeding up X applications over ssh on a slow network connection? In this specific case, I am accessing a server located in west coast from a laptop in east ...
8
votes
1answer
2k views

Dual network connection

I have a usb cellular modem and a Home LAN connection on my Ubuntu 10.10 box. Both work independently. I want to know how to have both connected at the same time, and be able to specify which ...
5
votes
3answers
17k views

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.
4
votes
4answers
3k views

Connecting to a network via another pc

What's a simplistic recipe to connect my PC to my WLAN through my laptop? I have one wireless network, one desktop that (for practical reasons) has no connection to the WLAN, and one laptop with ...
2
votes
2answers
513 views

How can I ssh to a remote server with an automated password and no key?

I have a remote server. I planned to use public keys to connect over ssh without typing the password but the remote system rejects public key authentication. So what is the best way to do it? What ...
22
votes
4answers
107k views

Connecting to wifi network through command line

I am trying to connect to my WEP network just using the command-line (Linux). I run: sudo iwconfig wlan0 mode Managed essid 'my_network' key 'xx:xx:... hex key, 26 digits' Then I try to obtain an ...
17
votes
2answers
17k views

How can I create a virtual ethernet interface on a machine without a physical adapter?

I have a Dell XPS 13 ultrabook which has a wifi nic, but no physical ethernet nic (wlan0, but no eth0). I need to create a virtual adapter for using Vagrant with NFS, but am finding that the typical ...
26
votes
13answers
31k 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?
10
votes
3answers
16k views

Only allow certain outbound traffic on certain interfaces

I have rather an odd issue. I have a server with two network interfaces eth0 and eth1. Each are connected to a different network. Each network has a internet gateway. The server has various outbound ...
6
votes
4answers
6k views

All commands that should be used to connect to wifi in command line

I would like to switch from gnome to awesome and I would like to connect my wifi network in command line (instead of using gnome tools). So, I searched on the internet and found approximatively the ...
5
votes
2answers
20k views

Two interfaces, two addresses, two gateways?

I have a system that has two network interfaces with different IP adresses, both of which are in the public address range (albeit via NAT in the case of the first one) and both of which have different ...
4
votes
2answers
20k views

Set Static IP in CentOS 6.4?

Most guides seem to revolve around modifying ifcfg-eth0, which doesn't exist on my system.. [root@Azaz07]# vi /etc/sysconfig/network-scripts/ifcfg-eth0 [root@Azaz07]# ls ...
16
votes
9answers
1k views

Simple file transfer

Given two Linux boxes on a LAN, what's the simplest way to transfer files between them?
6
votes
2answers
5k views

How do I share internet with Windows from my Linux box?

I have a Linux (Ubuntu 12.04) PC connected to the internet with a Greenpacket WiMax USB modem. I want to share the Internet connection with another computer running Windows 7 Home Premium, connected ...
9
votes
4answers
17k views

What can I use to monitor and log incoming/outgoing traffic to/from remote hosts?

I run a web server (Debian Squeeze on a VPS), and the graphs provided by the hosting company show consistently that around twice as much traffic is incoming to the server compared to the outgoing ...
1
vote
2answers
218 views

Editing my /etc/hosts.deny

I'm being trolled by China, and don't know why I can't block their request to my server. //host.deny ALL: item.taobao.com ALL: 117.25.128.* But when I watch the error log on my webserver tail -f ...
3
votes
1answer
14k views

How To Diagnose Faulty (onboard) Network Adapter

I'm looking for advice on diagnosing ethernet connectivity issues under Linux. I suspect it's a hardware issue, though I am not entirely sure. It's an nVidia chipset and ethernet adapter. The device ...
3
votes
1answer
915 views

Route SSH to host through interface

Is it possible to route all outgoing requests for SSH (port 22) to mydynamicdns.afraid.org via wlan0 instead of eth0 when both are connected? Since my IP is dynamic, I would like to use a name ...
1
vote
1answer
325 views

Always Forward Traffic Out The Interface It Originated On

(This is the original question but my eventual solution was too different from how I originally asked the question so I'm posting as a new question.) Background: I have a VM with three different ...
85
votes
12answers
268k views

How do I set my DNS when resolv.conf is being overwritten?

Most of the info I see online says to edit /etc/resolv.conf, but any changes I make there just get overridden. $ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by ...
93
votes
19answers
16k views

What is the fastest way to send massive amounts of data between two computers?

This is a situation I am frequently in: I have a source server with a 320GB hard-drive inside of it, and 16GB of ram (exact specs available here, but as this is an issue I run into frequently on ...
19
votes
3answers
28k views

Linux network troubleshooting and debugging

From time to time Linux and Unix users faced with various network problems. Many of these problems are presented here and at some others troubleshooting forums, but the are very concrete and contains ...
31
votes
7answers
38k views

Linux: allowing an user to listen to a port below 1024

I need to allow an user (different from root) to run a server listening on port 80. Is there any way to do this?
20
votes
5answers
7k views

What is a socket?

Could someone explain to me what a socket is? I see it in many acronyms in context of SSL, etc. Also, why is it called a socket? Is it purely because it was what a name they invented? Or was it the ...
21
votes
2answers
8k views

Is there an easy way to programmatically extract IP address?

Is there an easy way to programmatically extract IP address, without tedious parsing of ifconfig? I would not mind simple command output processing using sed to do it but not processing multiline ...
17
votes
3answers
23k views

How to find what other machines are connected to the local network

How can I see a list of all machines that are available on the LAN I'm am part of.
11
votes
4answers
40k views

How can I change the default “ens33” network device to old “eth0” on Fedora 19?

I've just installed a Fedora 19 on VMware workstation 9. The default network device is "ens33" instead of "eth0" on RHEL. The reason I have to use "eth0" is that the license component of one of our ...
17
votes
5answers
15k views

Sending audio through network

This is a rather crazy idea. I am planing to set up a configuration that would send audio being played on my laptop to my home server via local network so that the sound is played on the server ...
4
votes
1answer
53k views

Adding two default gateways in Debian interfaces file

This is my interfaces file: auto eth0 iface eth0 inet static address 192.168.1.10 netmask 255.255.255.0 gateway 192.168.1.1 auto eth1 iface eth1 inet static address 192.168.2.10 ...
20
votes
4answers
80k views

Why the default eth0 interface is down by default on CentOS?

I am already a little bit familiar with Linux distros like Debian or Ubuntu (yeah, very similar) but I wanted to try Red Hat based - CentOS 6.2 . I have installed it on my Windows 7 host in virtualBox ...
8
votes
2answers
8k views

wlan number assignment

How or where does Linux determine the assignment of a network device? Specifically, wlan0 or wlan1 for wireless USB devices. I plugged in a TP USB wireless a while ago, and it was assigned wlan0. I ...
5
votes
1answer
5k views

How to diagnose a reliably unreliable connection?

Where I'm living now, the internet connection (wired) shows the following weird symptoms. They seem to be independent of whether I use host names or IP addresses. Pinging works Skype works Wget ...
13
votes
1answer
10k views

Buffer size for capturing packets in kernel space?

Going through the man page of tcpdump, it seems kernel can drop the packets if the buffer is full. I was wondering if: that size is configurable and/or where can I see the size for my distro? From ...
5
votes
2answers
4k views

Routing for multiple uplinks/providers

I have a PC with two internet connections. The first one is an Ethernet interface to connect to my local network and access internet via my router. The second one use a GSM modem to connect with ppp. ...
5
votes
2answers
5k views

Use an USB tethered phone as network adapter

I am running CentOS 6 and was able to tether my HTC phone using a proxy called proxoid . This allows me to redirect HTTP. But how do I redirect the entire TCP traffic, e.g. if I need to setup openvpn ...
4
votes
3answers
4k views

Send duplicate packets over two Internet connections

I need to duplicate an RTP stream over two different (non-reliable) Internet connections. On the receiver side, I will probably run a custom program that will use a buffer and rebuild the stream ...
7
votes
2answers
476 views

Strange temporary network outage in Linux

I'm facing a very annoying problem that I noticed a week from now and for which I can't find an answer: my network suddenly stops responding, usually coming back exactly 25 seconds later. I was using ...
7
votes
2answers
1k views

Share keyboard over network as separate device?

I am trying to achieve something similar to this: http://superuser.com/questions/67659/linux-share-keyboard-over-network The difference is that I need the remote keyboard to be usable separate from ...
4
votes
2answers
8k views

How do I resolve samba share to IP address or host name

I have a list of hosts in the network providing shares via SAMBA. How can I determine either IP address or the host name of one particular host, e.g. the one with the name “SASAK02”. The output of ...
4
votes
1answer
2k views

multigateway routing for specific src port

I have two gateway to access internet, somehow I want to load balancing it, so far its working, but some connection or service need persistent gateway IP to be used, so the client should never change ...
14
votes
5answers
17k views

Why does SCP hang on copying files larger than 1405 bytes? [duplicate]

I'm trying to copy a file from one of my local machines to a remote machine. Copying a file with size upto 1405 bytes works fine. When I try to scp a larger file, the file gets copied but the scp ...