Linux Networking refers to any networking function performed by a server running Linux. A Linux server operating as a router or firewall are the most common applications.

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Is IP range or vLAN traffic mirroring possible with Linux?

I am dealing with a network monitoring issue in a medium size hosting platform (10 Gb). Some of the network devices can only do 1-2 SPAN ports. In order to get some more flexibility I'd like to use a ...
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19 views

How does the captive portal redirect work behind the scenes

As a project I am building my own captive portal web pages for "unauthenticated" users. Those are users that have not hit a button on my captive portal page. I want this to be out of band (like a ...
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Static ips aren´t working in ubuntu virtual machines

I want to set a static ip to a ubuntu vm client and other static ip to other ubuntu vm server. Im doing this like this: sudo gedit /etc/network/interfaces Then in the ubuntu vm client file: auto ...
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23 views

Forward all traffic when connected to a hub

I have a Ubuntu with two NICs. eth0 is connected to a hub and eth1 is connected to Internet. eth1 is used to do a point to point VPN using openVPN. So I have a tun0 interface. the VPN tunnel endpoints ...
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1answer
25 views

How to create virtual networks by using libvirt?

I have installed qemu/kvm and have tried to create some virtual machines and network them together. What I would like to achieve is 2-3 virtual machines in their own private network (e.g. ...
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1answer
34 views

Default gateway and ARP confusion

I have the following configuration (I'd post a pic but not enough rep for more than 2): PC1 (10.0.2.10/24) and PC2 (10.0.2.137/29) are connected to a hub, which is connected to a router on interface ...
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29 views

what is the “ip route” equivalent of “route add -host” in linux?

Specifically, route add -host allows me to specify the host via hostname to add a route to a host, e.g., route add -host www.google.com gw 192.168.1.1 However, I cannot find a way to do this using ...
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17 views

Add new subnets to KVM Host

I need to assign a handful of /27 subnets to my KVM host node (Centos 6). I routed them correctly at the Cisco switch, so that's all go. Traceroute & ping works fine on gateway on each subnet, ...
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1answer
49 views

Find network percentage of NIC [closed]

So I have created a Linux resource monitoring tool that pulls various resource information. One of the fields I am trying to pull is the percent of network throughput on my NIC. So if I have a 1 ...
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29 views

network access issue and triage

We have two hosts in same vlan with same route rules. One of them is able to connect to an outside IP while on another I get failed: Connection timed out when testing the connectivity through netcat. ...
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16 views

iptables/nat/prerouting ignores UDP packets?

The same effect on many servers with various kernel versions. There are multiple Iptables DNAT rules: iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 12345 -j DNAT --to-destination ...
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1answer
50 views

How to properly permanent enable ip forwarding in Linux with systemd?

I try to enable ip forwarding (between enp0s3 and tun0 interfaces) and write net.ipv4.ip_forward = 1 in /etc/sysctl.conf. After restart I have $ cat /proc/sys/net/ipv4/ip_forward 1 But forwarding ...
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19 views

How do I properly configure KVM

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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1answer
23 views

Routing via sub-interfaces not working?

I'm trying to isolate outbound network traffic to a specific target for metering purposes, so I thought I'd route it via a dedicated IP address. In order to achieve this I have setup a subinterface ...
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15 views

ARP cache getting null mac over a bridge

I have an interface eno1 and a bridge br0 $ ifconfig br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.250.53 netmask 255.255.255.0 broadcast 192.168.250.255 ...
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14 views

overlapping subnets - how to give one precedence?

I have Linux devices with a single ethernet interface and two IP adresses. The first (eth0) is statically configured to 10.1.1.146/24. The second (eth0:1) is configured via DHCP and it may happen ...
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17 views

SSH stops responding on all AWS EC2 instances at the same time

I've noticed SSH connections hang on all my EC2 instances (ubuntu), and eventually fail (with 'broken pipe') around the same time, 7 to 9pm in the evenings. HTTP and telnet continue to function ...
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19 views

How do I force specific interface to use different driver in RHEL?

We have Dell Poweredge 630 server which has 2 NIC Interface. We bought Intel's FTLX85.. module for those 10Gbit ethernets. 2 interfaces were using bnx2x driver of Broadcom. I installed Intel's ixgbe ...
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1answer
22 views

Asterisk hacking defence: “Call setup” in tcpdump from denied IP number

I am running Asterisk 11.7 on Ubuntu for my small business. These last days someone could access the server and make all phone extensions ring in regular intervals. I would like to understand how that ...
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1answer
18 views

Network interface fails to come up under heavy traffic

We're investigating an issue with our kit, which is an IP camera running Busybox Linux on a Ti-Davinci SoC. On one particular site there is a lot of network traffic (over which we do not have ...
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2answers
32 views

Percentual dynamic bandwidth control with tc

Does anyone know if tc (iproute2) can be used to percentually divide the currently available bandwidth? We're on a GPRS connection on which the available bandwidth changes frequently. What I want to ...
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2answers
27 views

How safe is IPtables whitelisting?

I am deploying some VPS and of course, security is a big concern. I read that IPtables whitelisting is the best way to safeguard your machine. So I set up the follwing : echo "Flushing rules" ...
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9 views

http://127.0.0.1 returning 401 Unauthorized [migrated]

I have a CentOS 7 box and have a service running on port 32400 (Plex Media Server) which is trying to pull some information via HTTP to http://127.0.0.1:32400/library/changestamp but a 401 response is ...
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9 views

Setting up bridge for domU to be accessed from external network(internet)

I am trying to setup virtual guests(PV) using xen 4.4 (xen-tools) on debian 8.3. Problem is that I fail to configure bridge properly I guess ^^. I have setup an interface xenbr0 that uses same IP ad ...
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7 views

How can I create separate/isolated regions on a home network? [migrated]

I currently have a flat network at home. My boradband router comes in and is connected to a switch, which supplies the Ethernet drops within the house. I also have a wireless router connected to the ...
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13 views

Adding an ip6ip6 tunnel in Linux fails silently

This is on Debian Wheezy. I'm trying to add an ip6ip6 tunnel like this: # ip -6 tunnel add v6tunash01 mode ip6ip6 local 2a02:27f0:2:246::2 remote 2a02:27f0:2:306::2 No output. But the device ...
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4 views

Use ubuntu 14.04.3 box as a wireless access point, no dhcp server and eth0 to wlan0 bridging [migrated]

I noticed that I had a 300Mbps N wireless adapter laying arround so I decided to use it in my ubuntu server to expand the range of my local nework, that server is being used as a samba and ftp server, ...
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1answer
21 views

CentOS7 Network Bridge Fails on boot until cable unplugged and plugged back in

I have a problem with a brand new CentOS 7 server I am trying to set-up. I have set-up a network bridge as per instructions on the redhat documentation website and it all works great until I reboot. ...
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9 views

How to configure Spark client running in a Docker container for two-way communication with a remote Spark cluster?

spark-submit seems to require two-way communication with a remote Spark cluster in order to run jobs. This is easy to configure between machines (10.x.x.x to 10.x.x.x and back) but becomes confusing ...
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45 views

Why is CentOS 7 ignoring NETMASK?

I have a networking issue that I eventually tracked down to an incorrect network prefix setting. ip addr is reporting that the current prefix is /8 when it should be /24. However, when I look in ...
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Can Spark be configured to listen on multiple network interfaces/ip addresses?

The nodes in my Spark cluster have two network interfaces each, one public and one private. Using the SPARK_MASTER_IP environment variable, I can configure Spark to listen on port 7077 on one or the ...
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10 views

Bridged qemu machine cannot receive packets, these are dropped [migrated]

I've created virtual machine (ppc) with bridged interface (using bridge helper) on archlinux. Machine can send packet out, but cannot receive anything. I can see packets (dhcp discover,request and/or ...
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36 views

Git Failed to connect to 127.0.0.1 port 8087: Connection refused

I'm installing the array database rasdaman, when I go to the step "make" , it begins to: git submodule update --init --recursive Cloning into 'third_party/googlemock'... but I don't know what ...
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21 views

Sending duplicate packets to the wan ip address

I'm in need to send duplicated packets to the remote host (wan ip address). I'm aware that -j TEE would do just that on the LAN, but what about WAN? iptables -I POSTROUTING -t mangle -d x.x.x.x -j ...
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2answers
37 views

Linux Hostapd registers as WEP, but I want WPA2-PSK

as usual to respect the community, I have traversed a bajillion articles and re-read the manual and still can't seem to get past this issue. I'm trying to create an access point in Linux(linaro on a ...
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33 views

Unable to bind a large Ipv6 block in Centos 7

I have ipv6block xxxx:xxxx:xxxx:xxxx::/64 block to bind to my interface on centos 7. I have tried to use: ip route add local xxxx.xxxx.xxxx.xxxx::/64 dev lo That was according to the anyip ...
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1answer
15 views

PPTPD-server split tunnel

Normally the client has to set up the VPN connection to be a split tunnel (not routing internet traffic trough the tunnel, but still have access to local resources), but is this possible to define on ...
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1answer
32 views

PPTP with restrictive access to local network for connecting clients

How can I restrict access to my local network for VPN-clients connecting to a VPN-server (PPTPD) located on my network? I would like clients to be able to connect to my linux node running a VPN ...
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20 views

Debian Preseed: Installation process stuck at 18 % at finishing-installation

My Preseed installation of Debian is stuck at 18 % and i don't know what's wrong. Can you help me please? Here is syslog screen: Syslog Here is my preseed file: #C ontents of the preconfiguration ...
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1answer
31 views

route table issue when I appended option net.ifnames=0 to grub2

I appended two options net.ifnames=0 biosdevname=0 to grub2 because I want to change default network name to old name eth0 on RHEL 7. After that, I edited /etc/sysconfig/network to set default ...
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17 views

Debug slow lan (ssh, nfs) file transfer

I've got two linux boxes attached to a gigabit switch. They both have gigabit NICs, cables are cat7. Testing the network with iperf shows a fast connection but transferring files with rsync, scp, or ...
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2answers
50 views

IPTABLES: Route outgoing http requests to eth1

I am trying to route all outgoing HTTP requests LEAVING my server to go through a proxy (tinyproxy) on another server. I want the transmission to the proxy to use our LAN which is on eth1. No matter ...
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18 views

How to diagnose netstat: no namelist

I had to replace an NIC on my HP Proliant Microserver, running FreeNAS 9.3 In my crashplan jail, I now get "netstat: no namelist" as a response when I execute the netstat command. How to I diagnose ...
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32 views

Why does my network work with an incorrect broadcast ip?

I have a block of public ips. The network is /28 starting at .80 By that rational, the broadcast ip should be set to .95, however the broadcast ip set in /etc/network/interfaces for every server is ...
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9 views

Debian preseed: DHCP ok , PXE-TFTP KO

to automate install of debain by preseed file, I builded a debian Jessie with tftp-hpa and pxe package installed on. The DHCP is managed by my windows server. All workstation get correct IP address ...
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19 views

Use of PTPd on RedHat/CentOS

I need to create a reliable and accurate synchronization between two CentOS 6 machines connected through a direct Ethernet connection. I've seen that on Linux several implementation of the IEEE 1588 ...
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23 views

Iptables Port redirection don't take effect

Im tying to setup a mitm proxy to sniff my Android smartphone. I found this helpful tutorial. At the point where I need to teach Ubuntu to redirect everything from port 8080 to 443 and 80 I'm running ...
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25 views

Strange iperf3 behaviour with UDP streams

I am using iperf3 verson 3.0.11 to measure the throughput of a UDP stream between two virtual machines. The virtual machines are deployed via OpenStack. Of the physical hosts, one is located in ...
2
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1answer
38 views

Basic forwarding on Ubuntu not working

I have the following setup, minimized to explain the problem: _________ |Desktop | ...
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65 views

DNS_PROBE_FINISHED_NXDOMAIN when trying to acess page from a local server

I'm working in a company where we use a local server in linux to store some data, particularly our BugZilla, Wiki and a subversion repository. The server is accessed both locally from the development ...