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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Can't connect to 2 different Linux computers via VNC (local network)

I have a problem connecting to Vino VNC server with 2 Linux Computers running Xubuntu. The computers are Based on the ODroid U3 chip which is ARM based. When both of the ODroids are on the same ...
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3answers
695 views

How to find out capacity for network interfaces?

I could get the capacity for the network interface by lshw, but which file in sysfs is this information stored(i.e. which file in /sys/class/net/eth0/device/ directory)? $ sudo lshw -class network ...
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3answers
72 views

Is it possible to route network traffic according to user ID?

On my Debian system, I'd like one of my users to use a different network interface as their default route for all internet traffic. I know how to use iptables to block the other interfaces, but not ...
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596 views

disable a network interface on booting ubuntu

I use ubuntu 12.04. I need to boot with one of the network interfaces 'eth1' down. I tried adding sudo ifconfig eth1 down to /etc/rc.local However it seems the interface is brought up and ...
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1answer
110 views

Linux 25 port routing (tunneling/forwarding)

I have: 1) Centos server 1 with postfic/dovecot mail servers IP1 45.45.45.45 (DNS: host1.com.ua) server 1 cannot make outgoing request to 25 port because Internet Service Provider block it! ...
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1answer
54 views

How do I close ports in Linux for security reasons (KVM)? [closed]

I am going to set up a KVM virtualization server on CentOS. The host machine and several of the VMs will have a dedicated IP addresses. I'm going to need to close off unused ports and probably ...
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2k views

eth0 NIC Link is Down repeating message in kernel log

I've noticed since few days ago that same repeating kind of messages occurs and I positively can say that nothing was intentionally changed (installed/uninstalled) in that period. here's sample of ...
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110 views

Couldn't load target `DNAT':No such file or directory

Trying to do some ipv6 nat and running into an error from ip6tables $ip6tables -t nat -N IPV6-BRIDGE $ip6tables -t nat -A PREROUTING -p all -d 2600:3c01::f03c:91ff:fe6e:2563 -j IPV6-BRIDGE $ip6tables ...
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44 views

Pinging to google.com from a particular interface

I am connected to the internet via wlan0(wifi) and also have an ethernet port(not connected to the internet). I am looking for some iptables rule / route addition, which will let me do a ping via eth1 ...
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3answers
412 views

Which private IP addresses can I use? [closed]

I have a dedicated server where I'm running several web-facing virtual machines on public IP addresses; I pay my hosting provider for each IP. I would also like to run virtual machines with private ...
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1answer
2k views

Should /etc/hosts contain an entry like '127.0.0.1 localhost myhost.example.org myhost'?

When looking at a variety of Linux and FreeBSD systems, I've noticed that on some systems /etc/hosts contains an entry for the public hostname of the host, but not on other systemst. What is the best ...
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564 views

Multicast route setup for multiple interface

Currently I have the below eth5 to receive multicast data for 239.1.1.31. It works. $ ifconfig eth5 Link encap:Ethernet HWaddr E4:11:5B:94:E1:F3 inet addr:10.185.2.2 ...
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2answers
117 views

How do I throttle network activity in Linux?

How do I throttle network activity, system-wide? Say, I'm running rsync on a large archive with a cron, or a torrent server, or both. It's important that these activities will be running, but they ...
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1answer
440 views

Running a custom script when StrongSwan connection is established

I have StrongSwan VPN server set up on a Debian host, and would like to run a custom script when a client connects to it. The only thing I have come up with is periodically checking the contents of ...
8
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1answer
394 views

TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page ...
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1answer
390 views

What's the difference between eth0:1 and 2nd eth0?

In Ubuntu server, I configured eth0:1 like this in /etc/network/interfaces file # The primary network interface auto eth0 iface eth0 inet static address 192.168.1.111 netmask ...
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29 views

Do I need a firewall if the service doesn't listen on all interfaces? [duplicate]

Short version: I have a CentOS 6.5 with two NICs, one connected to the internet and one connected to the internal network. The services that shouldn't be accessible to the internet don't listen on ...
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3answers
75 views

benefits of iptables on VPS? [duplicate]

Say I have a well updated Linux VPS serving HTTP content on port 80 using apache. What would I gain by enabling IPtables? I can see no obscurity gains since the machine has a port open. Also, since ...
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178 views

Http Persistent Connection (keep-alive) and port numbers

Is a persistent http connection (keep-alive), always bound to a specific port, or can it use a range of ports?
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2answers
63 views

APF and iptables on router - disallow SSH on specific subnet host

I have a CentOS terminal working as a router with APF installed. Also 1 terminal with 3 NICs (3 IPs) is using that router as a Gateway to access the internet. What I want is APF to block SSH access, ...
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1answer
231 views

Mininet additional veth pair between host and server

For those who don’t know - Mininet is a tool that allows for the automated creation of multiple OVS switches, chroot linux ‘containers’ as hosts and links them all together to prototype OVS powered ...
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1answer
182 views

Linux IPSec between Amazon EC2 instances on same subnet

I have a requirement to secure all communications between our Linux instances on Amazon EC2 - we need to treat the EC2 network as compromised and therefore want to protect the data that's being ...
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253 views

iptables - hashlimits, why it calculate all to seconds

I've tried to set 'synflood' limits with hashlimits, those are my snippet of rules: iptables -A SYNFLOOD_CHECK -p tcp --syn -m hashlimit --hashlimit-above 10/s --hashlimit-burst 6 \ ...
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1answer
4k views

Unable to add a static route: SIOADDRT: Network is unreachable

I've been bashing my head against a wall for a few days trying to figure this out: My ifconfig is: eth0 Link encap:Ethernet HWaddr 00:50:56:BB:XX:XX inet addr:192.168.36.132 ...
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1answer
90 views

IPTables: Firewall with just one Eth device? [closed]

Admittedly I am a novice in the area of firewalls. But I have read on the IPtables and Firewall theory and command options. There is a general diagram by Rusty Russell, the creator of IPtables: ...
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2answers
658 views

ARP responds with single MAC address on Linux server with multiple interfaces on the same network

Linux server has 2 active network interfaces: IF:eth1 IP:192.168.1.1/24 MAC:11:11:11:11:11:11 (1GbE) IF:eth2 IP:192.168.1.2/24 MAC:22:22:22:22:22:22 (10GbE) The idea is that the ...
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1answer
74 views

Forward a host network traffic to another host with the exception of the ssh service

I am trying to redirect all the network traffic received in a old host to a different new host. For that i created two new rules on iptables of the old host: echo 1 > /proc/sys/net/ipv4/ip_forward ...
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219 views

Proxmox internal network configuration

We have several servers (with one nic) staying in one rack in hetzner. Proxmox is installed on each one, and they are combined in proxmox cluster. The goal is to create network, between virtual ...
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1answer
263 views

How to ping ipv6 interface

I'm trying to get familiar with ipv6 I don't understand why I can't ping this interface at the inet6 addr eth1 Link encap:Ethernet HWaddr 08:00:27:77:9e:77 inet addr:192.168.33.10 ...
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1answer
281 views

Automatically acquire IPV6 address in CentOS 6

The network has fixed IPv4 address, and automatic acquired IPv6 address. Does anyone have an idea how to setup? Thanks a lot! I didn't use NetworkManager. The following is my setting, but it does not ...
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99 views

CentOS 6.5 with Oracle XE in virtualenv

I'm running a CentOS 6.5 with installed Oracle-XE. I created a virtualenv where I run my Django-NGINX-Gunicorn Webserver. Locally I can access XE via SQL Developer but when I try to access the ...
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1answer
86 views

How can I configure iptables to forward and forget?

I'm trying to create a front controller where users can connect to a specific port and have their connection redirected to a different IP/port. The reason I'd like to be able to do this is for ...
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2answers
409 views

Routing Internet traffic through computer on another subnet

Ubuntu box server has 2 network interfaces: eth0 50.57.71.100 eth1 10.182.161.100 Ubuntu box client has 1 network interface: eth0 10.177.30.100 server and client can already talk to each other ...
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Improbably high bitrate in the output of “iw wlan0 link”

I am trying to determine the bitrate of a wireless connection that uses the nl80211 driver on a Linux 2.6.39 machine. I am actually using a Netlink socket internally, but the effect is the same as ...
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1answer
164 views

Tunnel interface inside Virtualbox IP forwarding

I am working on a solution to expose a development stack that resides inside a Virtualbox guest up to the Internet through OpenVPN tunnels. OpenVPN client fires up inside the guest VM and connects ...
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2answers
53 views

Network Buffer Usage

I am facing some issues with my Application, and am curious to know the network buffer usage at any given moment. I am using a CentOS 6 linux Machine. I know the Default values are present in ...
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2answers
53 views

SCP version of - ssh -A -t -l root 192.16.4.9 ssh -A -t node-17

I'm on a vpn. I ssh to a machine through another machine like so ssh -A -t -l bob 192.16.4.9 ssh -A -t node-17 I now need to scp a file from node-17:/tmp/something. How can I do the above in one ...
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31 views

Routing traffic based on source (Linux)

I have two interfaces on my server; eth0, wich has one public IP address; and eth1, on which 3 IPS are attached. What I'd like to achieve is route traffic coming to the public address configured on ...
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1answer
39 views

Sharing a file system, or how to horizontally scale access to files

My API mostly serves up stuff from the database, but a big part of the product is generating images by combining SVG files with large pattern fills (~50MB tiff files). The API can scale ...
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1answer
50 views

Unable to nmap open port. IPTables has it listed as open

I have an IPtables firewall set up on a single system. I'm trying to nmap it with the following command: sudo nmap -Pn -A (IP addr) I expect everything incoming to be filtered except for ports 22 ...
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1answer
42 views

Command “ip rule show” not showing anything

I try to list all routing rules, and as far as I know this should be accomplished with the "ip rule show" command. In my case there is nothing returned (really nothing at all). Why? Could it have to ...
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2answers
49 views

Forwarding all connections to different address

I have a script that tries to connect to rabbitmq using default url and port (localhost:5672). Is it possible to make linux redirect all connections to this url and port to different server? I am ...
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0answers
51 views

Forward connecting IP address to KVM guests

I'm running kvm with iptables configured to use DNAT and masquerading. However the guest machines are logging the host bridge ip not the connecting client IP address. Is there a way to configure ...
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157 views

Configuring VRRP with keepalived on two machines - interaction with proxy arp

Let's assume we have the following topology for our network: Host1------- Router1-------Router2----------Router3-------Host2 and we want to configure vrrp on the two hosts with keepalived so that ...
2
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1answer
63 views

Is the ethx mac address of a VM the same as the mac address of the corresponding tap interface?

I have a single node openstack install on an ubuntu machine. For some reason that I cannot figure out, the linuxbridge is dropping packets from this VM. My iptables seem to be fine (atleast as far as ...
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80 views

CentOS 6 network failling to connect network after exporting VM from VirtualBox to VMWare Player

I have installed a CentOS 6 virtual machine in VirtualBox and I want to export it and use it under VMWare. But after exporting, network does not work. There are some other interfaces created with the ...
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106 views

VPN route works for browser, but not for Curl

I am using "Cisco AnyConnect Secure mobility Client" to set up a VPN connection. This works just fine for connecting web browsers, but when I tried doing the same connection with Curl I get: About ...
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7 views

rhel4 user not working on different domain

I am using a red hat server 4. Installed oracle on it for network database Previously when i was looging as root in gui and opening terminal it was showing like this $root@localhost> but now it ...
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2answers
2k views

Is it possible for L2TP VPN to do auto route configuration for client during connected?

We've setup a L2TP VPN server with this tutorial, everything works like a charm. The only issue is We don't want client to route all traffic using this VPN, only a particular subnet, e.g. ...
7
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1answer
307 views

Is ISP's Equipment Misconfigured? Getting Martian Packets on Internet Interface

We have a /28 block from our ISP. Let's say 1.1.1.240/28 with a gateway of 1.1.1.241. We are getting martian packets from another customer over at 1.1.1.214. They are sending broadcasts to 1.1.1.255. ...