Managing and using network connectivity on a unix system

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How to forward IP traffic between wlan0 and eth0 without killing network performance on the forwarding machine

I have a laptop running Debian 7 that connects to my building's Wifi. I want so share this network connection via the laptop's Ethernet port. I have setup a script below to do this based on some ...
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3answers
84 views

What's the most effective way to detect nmap scans?

As the title says, I am interested in detecting any nmap scans directed on a (my) GNU/Linux host. I would like to use snort in combination with barnyard2 and snorby for this, or if possible to perform ...
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28 views

How do you connect app and DB servers from separate containers?

With Docker, how can I make the DB in one container accessible by the app server in another?
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2answers
30 views

Start Networking at login

What I would like to do: I would like to start my wireless network after login (As apposed to starting at boot). Using my login credentials to run the command: sudo netctl start network. Instead of ...
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2answers
104 views

Add network eth with a separate gateway

OS: Debian Currently I have only 1 network connection setup (br0). I'd like to connect a second network connection (eth3) to a separate network/gateway. Everything should continue to be sent ...
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1answer
39 views

Diagnosing lost network connectivity on Ubuntu

My first question here so please be gentle. :) I have a Linode running Ubuntu 14.04, with a stack managed by ServerPilot.io. Only real modification is that I'm running HHVM in a limited fashion. ...
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2answers
73 views

Debian - how to run a script on startup as soon as there is an internet connection ready for use?

I am running Debian 7 Wheezy and I need to start some screens on startup as soon as there is a fully functional internet connection. However, not, if the internet connection broke and was connected ...
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1answer
35 views

trouble bridging tap0 and tap1

I have a GNS3 router that is connected to tap1 in my host. On the other hand, I have an user application connected to tap0 running locally in my host. I can ping both the router and my application. ...
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3answers
49 views

Listen on port that is already listed as source port of an established connection?

If a connection is in an ESTABLISHED state with local address 127.0.0.1:45000, would it be possible for a local process to bind and listen on the same port 45000 or would that port be considered ...
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1answer
29 views

Why is ping6 using IPv4 socket?

I enabled IPv6 in a CentOS 7 server and everything is working as expected, except for ping6: it is showing 3-5 delays between requests (but the RTT is fine): $ ping6 www.google.com <...5 ...
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2answers
48 views

Should /etc/hosts contain the domain name or the FQDN?

If I want to add an entry to /etc/hosts to resolve all traffic for example.com to 1.2.3.4, do I need to add 1.2.3.4 example.com 1.2.3.4 www.example.com 1.2.3.4 smtp.example.com 1.2.3.4 ...
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1answer
64 views

kernel martian source to and from same IP

We are intermittently seeing kernel: martian source log entries for eth0 on a couple of our servers. The interesting thing is that they are to and from the same IP. For instance: Nov 4 02:20:27 ...
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1answer
22 views

U-boot static IP doesn't seem to “apply”

When I enter the command setenv ippaddr xxxx.xxxx.xxxx.xxxx it doesn't seem to actually connect to the network on that address. I have a private network set up with the address in the same subnet ...
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1answer
33 views

Relay server for generic TCP traffic?

Here's my situation: I have a computer (Mac) on a school network that I want to port forward TCP 5222 to for ejabberd, but of course I can't. I have a server at home (Mac with FreeBSD VM) that I can ...
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1answer
55 views

Cannot install Intel NIC in Debian squeeze

I've upgraded an old machine to a brand new i3 (Asus H97-PRO motherboard, cpu and ram only) and Debian accepted it quite well, except for the network card. I'm having some trouble trying to install ...
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1answer
51 views

How to kill processes using a network interface

The issue I'm having is that whenever I just remove my USB wifi card, it kernel panics and reboots the system. Is there some way to detect and kill any processes using the wifi card automatically to ...
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1answer
46 views

Can I add to Linux's privileged ports?

Ports under ~1000 are privileged in Linux. That is to say only root can bind them. There are various reasons, amongst them security: You know that whatever binds one of these ports had root (or ...
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2answers
100 views

Understanding hostnames

I was recently setting up an MTA on a VPS, and while configuring it I realized I’m quite confused about the concept and implementation of hostnames in Unix. I have a solid understanding of the DNS, ...
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0answers
25 views

Run two interfaces on one network card

Is it possible to run two different network interfaces (e.g. being connected to two different wlan-networks) on one card in parallel on linux? If yes, how? If no, why not (I would be glad about a bit ...
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0answers
50 views

connected to ethernet and wifi, “route” browser's connection to wifi only

Sometimes, in my company, I have to work with a different network (through ethernet) that has no internet. On the other hand, I do have access to out Wifi, which has internet. Since I have to spend a ...
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0answers
28 views

Xen domU sort of ignores /etc/network/interfaces

I have a Debian based Linux installation, that gets around: It started out on a physical system, then I moved the OS into a VMware container and then into a Xen container. As physical and VMware ...
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0answers
67 views

Setting up a 802.11s mesh network for mobile devices to communicate with a wired server

I'm in the process of developing an android app that maintains a device's connectivity to a linux-based WiFi mesh network, and periodically sends status information (GPS, battery life, etc.) to a ...
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1answer
47 views

Can't use hostname for my linux machine

I installed apache on my RHEL machine yesterday and found I could access it from a browser using http://. Of course, sshing using the hostname was also working. So, I made an index.html file inside ...
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0answers
33 views

Workstation-like environment across Debian clients

At our university we have a workstation-like system. It's windows XP (or Win-7 on some machines) and you can sit to any computer and log in with your credentials. It seems to be pulling some of your ...
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1answer
26 views

Start a service on a network request (socket activation)

I have a program that under normal activation listens on some port. I don't want the program running continuously. Is there a "quick and dirty" way to wrap the application in a shell script or ...
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26 views

How can I compile and run a program designed for an older kernel version (2.6) in a newer kernel (3.16)?

I'm trying to run a driver for a network card, but it only supports kernels up to 2.6.32. I need to be able to use this piece of hardware to connect to the Internet. The device I'm using is "VIA ...
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16 views

What is the functional difference between wpa_supplicant and the system's /etc/networks/interfaces file?

I understand that one is a program and that one is a configuration file used by linux, but practically what is the function of each of these pieces in conjunction with my computer's network ...
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63 views

Connect to IPsec VPN using OpenSwan

I'm connected to Internet with a simple ADSL router with NAT. I have a smartphone and a laptop running linux. I need to connect to a IPsec server using OpenSwan. First I tested that it is possible to ...
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1answer
49 views

tcpdump won't capture entire packet

I'm using sudo tcpdump -A -s0 -ien0 port 80 | grep schemas-microsoft >> ~/Downloads/convert.txt to capture microsoft-schema xmls being sent throught the internet, when tcpdump is supposed to ...
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1answer
67 views

How can I manually reset RX / TX counters in ifconfig output without impacting data delivery?

CentOS 5.9 I'd like to reset the RX/TX counters in ifconfig output for an interface. My understanding is that these counters get reset during a reboot but I'd like to avoid rebooting. Is there ...
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1answer
18 views

Fedora does not load some sites in home network

Since I switched from Windows 8.1 to Fedora 20 (my first time Linux experience) I have problems in my home network. When I surf from the office with the notebook, every site loads fine. As soon as ...
2
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1answer
46 views

How to do mac spoofing on Linux Mint 17?

How to do mac spoofing on Linux Mint 17? Through macchanger -a I've tried to changemy mac address but new mac id doesn't authenticates successfully. pppd gives successful authentication message only ...
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1answer
66 views

Reverse DNS PTR lookups ocurring on each connection

I'm running a Debian-based VPS (Linux vps 2.6.32-042stab092.3 #1 SMP Sun Jul 20 13:27:24 MSK 2014 x86_64 GNU/Linux) which is behaving a bit strange. Whenever a new connection is established to it, it ...
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0answers
28 views

route -n gives output “route: fscanf”

If I boot my system and no interface has an IP address I get the above output. However if I give an interface an IP, even if I remove it again, this will disappear. Why does this happen? Is it that ...
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0answers
71 views

How to reach interface alias bond0

I'am setting up an interface alias with my bond0 network. Why am I not able to ping/reach the second ip address, in this case 192.168.30.84? However I can ping the address from another server. ~# ...
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1answer
14 views

How to apply a parameter to packet so TC can prioritize\classify it

I want to add a parameter to the packet so that I can later let TC (HTB in specific) prioritize my packet (based on filtering that parameter). I thought about filtering by socket but as I understand ...
1
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1answer
68 views

Allow multicast packages from the bridge to wire in KVM

On a CentOS 6.5 host, I have a couple of guests - Ubuntu 12.04 and CentOS 6.5. The Ubuntu guest is generating mcast traffic that is visible via a tcpdump on the br3 interface. It is also visible on ...
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1answer
68 views

Getting all IPs of devices connected to the same router

I have several linux devices connected to the same router (of which I am not a administrator). How can I find out the ip addresses of all other devices by executing some commands in one of them?
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0answers
59 views

Create virtual network adapter with own MAC and IP?

I have a server with 4 different IPs over one real NIC. Now i try to setup different virtual network adapter in debian with this IPs. The Problem is, that each IP needs also a specific MAC. Otherwise ...
0
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1answer
56 views

Isolate subnets on the same interface

I need to isolate Subnets on a linux machine CentOS that act as gateway. I have the following scenario. CentOS eth0 pub ip addres eth0.1 192.168.1.1 eth0.2 192.168.2.1 Now eth0.1 and eth0.2 can ...
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2answers
115 views

How to check programatically if the Ethernet cable is plugged in?

As you know, in Windows, when we plug in the network cable, the network symbol will change to another status. How can I know whether the cable is plugged in or not via the command prompt in Linux?
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75 views

TCPDump To Capture A Tracepath6 Datagram

I'm trying to use TCPDump to capture an IPv6 datagram using: tcpdump -c 1 -i eth1 -vvvs0 ip6 and dst host H2.net2 & tracepath6 H2.net2 I'm running this script on H1.net1; R12.net1 is the ...
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2answers
22 views

net cat client and server model

I tried to make server client model as below on one shell nc -l -p 8080 this works as a server and on another nc 127.0.0.1 8080 and this works as a client all of this is fine ... the ...
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0answers
26 views

NAT-T set up using 3 linux machines

I am trying to have a simple NAT-T setup using 3 linux machines. Linux1 Linux2(NATdevice) Linux3 (eth0) 192.168.1.51 <--->(eth1)192.168.1.80 & ...
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127 views

FreeBSD 10: CARP & LAGG interface incorrectly chooses state

I'm having an issue with my CARP configuration on a pair of FreeBSD 10 servers acting as NAS units. I'm using CARP so that the servers share a virtual IP with the goal of making failover somewhat ...
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60 views

How to populate /etc/network/interfaces automatically

I am trying to populate /etc/network/interfaces with a dhcp config for all interfaces at the first system boot (Debian 7.6 server). I modified the script in : /lib/udev/write_net_rules by adding: ...
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50 views

Why on my Linux PPPoE connection displays sometimes authentication failure?

Here is my log: Oct 18 09:51:52 -desktop pppd[2764]: Plugin rp-pppoe.so loaded. Oct 18 09:51:52 -desktop pppd[2766]: pppd 2.4.5 started by root, uid 0 Oct 18 09:51:52 -desktop pppd[2766]: PPP session ...
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0answers
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I'm trying to create a public TLD using BIND

I'm using these two guides: jackal777.wordpress.com/2013/11/19/custom-tld-for-local-network/ timg.ws/2008/07/31/how-to-run-your-own-top-level-domain/ When I run dig sokolovskaya.ssu, it looks ...
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0answers
84 views

Routing incoming source IP traffic to a loopback IP issue

I'm wanting to accomplish the following: I have a BIND DNS server setup where it is listening on ANY address and also listening in a BIND config ACL on 127.0.1.1. If there is another way where you ...
4
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2answers
202 views

Why is ping much faster when using -f

I'm pinging the same host from the same machine at the same time. And when using -f, the result is almost twice as good: [root@localhost Desktop]# ping 196.1.6.16 PING 196.1.6.16 (196.1.6.16) 56(84) ...