Managing and using network connectivity on a unix system

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3
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1answer
52 views

“legal” ARP poisoning by machine aggregating 2 NICs crashes us

I'm really not sure if that title makes any sense so apologies for that, but strange things are afoot, threats are being made and we need to sort this problem out; The situation: Our device (a ...
3
votes
3answers
437 views

How to allow only machines with specified ip to login via ssh?

I want to allow only machines with allowed ip(s) to login to my system via ssh. For example, userA can use only ip xx.xx.xx.xx or yy.yy.yy.yy to login via ssh, and no other ip can login as the userA. ...
1
vote
1answer
32 views

Which network interface is used if they are both the default gateway?

In this example below on my Linux machine, I have an Ethernet and Wifi interface established. Here is the route output: Kernel IP routing table Destination Gateway Genmask Flags ...
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2answers
49 views

How to run a script upon IP change

My Debian machine is currently part of my home LAN, behind the ISP box which handles all network related activities (DHCP, firewalling, telephony, IPTV, ...). A classical case of residential home ...
3
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0answers
16 views

download rate limiting based on network usage

I have a Debian Wheezy (Open Media Vault) server with a few different downloaders working most of the time. (Primarily FTP) I would like to be able to adjust the download limits of this server based ...
1
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2answers
28 views

Debugging “unable to connect to sendmail server”

In a corporate environment, we have a mail server which has only ports 25/tcp and 587/tcp available. When we use Perl Scripts (using HTML::Mail) to send hundreds of legitimate mails, it occasional ...
3
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2answers
123 views

Multiple machines on single network with same IP

I have a raspberry pi 2 that I'm using for a KODI media center that has the ip address 10.0.0.4. Another pi I just got is showing the same ip (derived from /sbin/ifconfig -a and listed under wlan0 for ...
2
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1answer
55 views

How is udhcpc executed and how to change it?

I am working on an embedded system and it uses udhcpc as its DHCP client. It seems to be running with the following parameters: /usr/share/udhcpc # ps | grep dhcp 5366 root 2432 S udhcpc -R ...
8
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2answers
311 views

“Pipe” Wi-Fi signal through Ethernet cable

Currently the Ethernet ports in the building I work in are down, but the Wi-Fi works. I have a Wi-Fi-enabled laptop (Ubuntu 14.04 LTS (Trusty Tahr)) and a non-Wi-Fi enabled workstaion (Debian 8 ...
1
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3answers
178 views

Putting a network interface up/down from command line

In Xubuntu 14.04, I tried to use both ip and ifconfig to handle a network interface, but they gave the same result. $ sudo ifconfig wlan0 down $ sudo ip link set wlan0 down both correcly put down ...
0
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1answer
65 views

Free and fast NAS software for arm

I own a bananapro computer and I wanna set up a NAS on it. I have already tried samba, but I don't like it very much. Is there alternative software for debian, that would work with Mac? Windows ...
3
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0answers
53 views

How can I know which IP address of a host is reachable from another?

I don't particularly need a "solution" to something, I'd just like to understand more of the landscape here. So on my CentOS box, I installed a CentOS VM specifically for learning Puppet. When the ...
0
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1answer
30 views

Auto mounting network share which is temporary offline

following problem: I have a server which needs to mount a windows network share in order to copy a file on it. So I added the share in the fstab so that it will be mounted on startup. ...
0
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1answer
152 views

Wwan connection on Debian and/or Arch

Arch and Debian installers want internet connection but manage to install most of their load w/out it. No Linux installer I'm aware of can configure wwan. I've only a wwan connection. On Ubuntu I ...
1
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3answers
74 views

Centralising Discs to Repository?

I have discs where is much variations. I would like to add the files of many OS to my central repository where the files originating from OS X have caused me biggest trouble when later viewing them in ...
0
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1answer
191 views

Linux Mint 17.3 not connecting to the internet when in terminal but able to connect using firefox, and i'm using proxy

I have installed Linux Mint 17.3 Mate on VirtualBox and have added a proxy, When using firefox I'm able to load webpages but when I try to run update of the system or to ping it fails , The update ...
0
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2answers
49 views

Collecting network information

I need to collect information about the network usage of each process. Nethogs presents the data I need in real time, I am trying to save the output to a file in order parse it and plot the data. ...
0
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1answer
34 views

Determine which network interface to use based on target IP

Say I have two network interfaces, eth1 and eth2, both of them connected to a different ISP. How can I instruct linux to use eth1 for all traffic to the IP 111.222.111.222 while eth2 is used for all ...
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0answers
14 views

YAST is trashed and wirless networking stopped

Running openSUSE 12.2 Mantis for some time with no problem until now.It will not load up wireless network and YAST appears trashed, with this error message anytime I try to fix it. "terminate called ...
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0answers
35 views

How do I specify an alternative bridge interface (not br0) when using qemu-bridge-helper

By following the instructions found at http://wiki.qemu.org/Features/HelperNetworking I can configure qemu with qemu-bridge-helper, however, I can't figure out how to pass a bridging interface option ...
0
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1answer
25 views

what is the meaning of “-m state --state RELATED,ESTABLISHED”? [duplicate]

I found this rules on iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT what is the meaning of -m state --state RELATED,ESTABLISHED ? and why without this rule ,I can not ping ...
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0answers
31 views

Some Issues on External IP Port Forwarding in Django Server

I want to run a home server. I managed to make my local IP address static, then created port-forwarding as below (which is enabled): However, when I make it on 80, it forwards to modem management ...
1
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1answer
34 views

Connecting to WPA network in FreeBSD

For whatever reason I am having a very annoying time just trying to connect to a network in FreeBSD. So the question is how would someone manually connect to a wireless WPA network in FreeBSD 11.0? ...
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0answers
65 views

Setting up bridged adapter for Arch guest, Windows host [closed]

I've tried many things that I've found online but I'm stumped. I'm using VirtualBox, my guest OS is Arch, kernel version 4.4.1-2, my host is Windows 10. When I set it to have NAT adapter, I get it ...
0
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2answers
123 views

Share my Windows 7 C folder with another Ubuntu Linux 15.10 Lenovo desktop computer

I would like to share my Windows 7 C folder with another Ubuntu Linux 15.10 Lenovo desktop computer. The following URL describes how to do this procedure. ...
0
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1answer
40 views

ssh RPi from PC - How to share internet connection?

I have Raspberry Pi connected with PC on eth0 port. I am using eth0 to ssh RPi. I have web application on RPi that requires Internet access. Now, I set static ip to RPi (192.168.1.50) and to PC ...
1
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1answer
21 views

Using iptables instead of ARP resolution

Due to a particular network configuration, I would like to associate MAC addresses to outgoing Ethernet frames using iptables instead of the ordinary ARP resolution, or at least have the ability to ...
0
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1answer
41 views

Host to Jail networking with vimage

I've got iocage jails with vnet=on (vimage virtualized networking) I've got a bridge1 with several jails' interfaces as members (vnet1:1, vnet1:2, etc) these can pass packets between each other. ...
0
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2answers
90 views

Command to detect if internet connection is wired or wireless

I would like a command to check if my internet connection is wired or wireless. I am using Arch Linux. I am doing this to display a different icon in lemonbar for different network configurations.
0
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1answer
37 views

I have no local IP on my CentOS 7.1 dedicated server

problem I've installed net tools and whenever I run ifconfig -a I come up with 2 network interfaces. Here is an example. [root@81756 /]# ifconfig -a eno1: ...
0
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1answer
27 views

How do I setup MAC spoofing in Fedora?

I would like to setup MAC spoofing in Fedora, similar do what Tails does to their Debian. Any idea how? Thanks
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0answers
16 views

How do I properly configure networking for a KVM virtual machine?

I have a remote dedicated server on which I have installed KVM. When trying to create my first virtual machine I am unable to ssh to the machine. I assumed that I needed another ip address so I ...
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3answers
36 views

Understanding, and viewing, how ports are allocated by ssh tunnels?

I was trying to figure out a small problem with connecting to vnc through an SSH tunnel today where one of the possible issues was that someone else was already tunneled to the port. Without going ...
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0answers
47 views

“link is not ready” error, vanishing network interfaces

I recently had a weird problem when trying to use airmon-ng. Here is its description: First, I plug in my USB WLAN adapter, and type ifconfig. Everything goes well and I see all interfaces are ...
2
votes
1answer
50 views

How to connect two VMs with different IP ranges to access each other?

Using KVM I have created four VMs, I have two public Ip addresses for my VMs, I know that I can assign these IPs to two of the VMs and connect them to internet by bridging my host's physical interface ...
0
votes
3answers
80 views

How to set the Default gateway

I'm trying to configure the network interface on embedded linux using ifconfig: ifconfig eth0 192.168.0.101 netmask 255.255.255.0 but I don't know how to add the default gateway as an ifconfig ...
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0answers
92 views

KVM network packet loss to guest

I am running a server with Debian 8.3, uname output Linux x 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3 (2016-01-17) x86_64 GNU/Linux I am using KVM to run a virtual machine with CentOS ...
1
vote
2answers
93 views

How do I check if an IP-address or a network is contained in other network in Bash?

I need to check if an IP-address or a network is contained in other network, e.g. if '10.1.2.3' is in '10.0.0.0/8' or if '10.1.2.0/24' is in '10.0.0.0/8'. Currently I use python for this, e.g.: if [ ...
0
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1answer
119 views

Linux Source Routing, Strong End System Model / Strong Host Model?

Can a multihomed Linux machine implement a true Strong ES Model? Specific Use Case I have a system with five different interfaces, each connected to the same subnet, thus the same gateway to the ...
0
votes
1answer
57 views

How do I set up passwordless authentication with non-root users?

Using two CentOS 7 servers, I set up passwordless authentication with root users. It works fine. I tried to use the same method (with .pub and authorized_key files) with other local users. But these ...
1
vote
1answer
31 views

Creating Encrypted Tunnel Between 2 Lans

I have 2 LANs and one of them is connected to the internet and I need to connect them together. Normally, a single cat6 cable is enough for connection however, this cable is going through a public ...
1
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1answer
75 views

Debian Jessie server has no internet access

I have a server running Debian 8 Jessie that constantly loses it's internet access for seemingly no reason. The server has two wired connections, the internet access is on eth0 and the internal ...
3
votes
1answer
104 views

Using iptables to redirect all traffic to local webserver

Aloha, I'm trying to redirect all traffic on my wifi router to a local webserver using iptables. I'm not sure i have got the command right and also I want to exclude the router IP (172.16.0.1) from ...
2
votes
1answer
40 views

When is a port considered being used?

I am getting port in use cannot bind on process restarts. I am trying to find out when a port is considered being used? Is it only when in LISTEN mode? Can it also be if a connection is open to the ...
1
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1answer
31 views

Connection is not established again after disconnect-connect ethernet cable

I have a situation where I have two devices connected to each other via ethernet interface, problem comes when I disconnect cable and connect them again after some time (it starts to work normally ...
3
votes
1answer
56 views

Why can't my servers talk to each other over direct ethernet connection?

I have two servers running RHEL 7.2. Each have 2 NICs. One NIC talks to a switch, and other is a direct connection between the two servers. One of the servers will be an NFS server, and the second ...
0
votes
1answer
76 views

Does “ip_forward” need to be enabled for any iptables SNAT/DNAT (postrouting/prerouting) rules?

I remember I had to enable ip_forward kernel parameter in the past in order to run SNAT/DNAT rules in iptables successfully. Today I was reading this post: ...
2
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0answers
39 views

SSH/web servers in Linux containers improve security?

Scenario: A 'gateway' machine functioning as a router and firewall, connecting a small LAN to the internet. The machine also runs a webserver (hosting a simple website) and an SSH server, providing ...
0
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0answers
50 views

How do I install and configure NTP on CentOS 7 from source? (include/ntp_crypt.h errors)

I unpacked the .tar.gz file for the newest NTP. I installed the gcc compiler and libcap devel. I ran the ./configure command with various flags and options. I ran make check and found an error. The ...
0
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2answers
128 views

Systemd wait for network interface to be up before running service

I have a couple questions about systemd. I'm having issues consistently getting my script to run once the network interface is up. I have tried Requires and After as seen below but is inconsistent ...