Routing (in IP-based networks) is the process of selecting paths in a network along which to send network traffic.

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routing cache in latest Linux kernels

As I understand, routing cache was removed since Linux kernel 3.6. In systems with older Linux kernel one could view the content of the routing cache with ip route show cache command and routing ...
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Separate Network Traffic on Two Network Interfaces

I am not an R&S professional, so much of that realm of computing escapes me. Could you lend your expertise in helping understand how to go about configuring the separation of network traffic on ...
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Redirecting loopback traffic through a router

For some tests purposes, I am running multiple socket-based applications on one machine and want to simulate "real" network conditions between them. I thought the simplest would be to redirect all ...
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Port Routing/DNS for individual program

Background Flickr has closed its http api leaving an https only api. My favourite uploader (the official Flickr Uploadr version 2.5 running under wine) is no longer maintained, so this change broke ...
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Send traffic to self over physical network on Ubuntu

I have a dual port ethernet NIC and let's say I have connected both ports in a loop and assigned the following IPs to the 2 ethernet interfaces: eth2 -> 192.168.2.1 eth3 -> 192.168.3.1 I want to ...
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How to set up ssh server with VPN tunnel? (Policy routing for sshd service)

It's difficult to me to explain in words, so I made diagrams. In short, I want this to work: Basically I want to be able to connect from my laptop [A] to my desktop [B] via ssh, and run terminal ...
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Is it possible to set-up a VPN in such a way that I disconnect from the Internet if it goes down?

How can I set-up a VPN so I loose connection to the Internet if it goes down? I use Ubuntu and have used the network-dialog to use a VPN; but if the VPN goes down, it just switches to the non-VPN (...
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765 views

Simplest way to set up multiple subdomains to separate VMs running on single host

Problem: I´m planning to set up several virtualized centos, rhel or ubuntu guest machines on a single centos host server (most likely using KVM). Each guest VM is running an instance of a webapp + ...
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Routing Tables: What is the effect of the RTF_IFSCOPE flag?

(Related to this question I posted a while ago on apple.stackexchange.) What is the difference between the following two routing table entries: default E.F.G.H UGSc 0 ...
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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 ...
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780 views

Fix “Route hash chain too long” without restart

On our production server (ubuntu 12.04, 3.2.0-63 kernel) routing cache reached its capacity. Modifying rhash_entries is out of the question, since it is a kernel boot param, and we can not restart the ...
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How to open VPN connection inside other VPN connection under Linux/Ubuntu

Is it possible to have two VPN connections on top of each other under Ubuntu? Scenario: My organization is quite large and has its own large network. Each group inside the organization has its own ...
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putting extra hops into traceroute6 on OpenBSD

I'm running OpenBSD, or maybe FreeBSD. I don't have lots of IPv4 addresses to waste, but who doesn't have a few billion of IPv6 ones? How do I add some extra IPv6 hops to a traceroute6, around pf(4) ...
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455 views

Throughput test setup with two local Ethernet interfaces

I'm currently testing the routing performance of a hardware device (DUT - Device Under Test) with the following setup (all addresses start with 192.168.): eth0 (29.2) <---> eth1 (29.1) eth2 (...
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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 ...
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Routing policy is not working

I have an Access Point with OpenWrt. On other host of the same LAN there is a squid (IP Address 192.168.80.148). I'd like to route packages with destination port 80 to 192.168.80.148. So I have root@...
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iptables and ip forwarding for failover

hi i have an ethernet nic interface with 4 additional virtual interfaces (failovers) all configured with public ip4 (IP-1 to IP-5) / netmask 255.255.255.255 / broadcast addr same as ip: eth0 -...
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Route VPN traffic through different proxies

I want to setup VPN server and route (based on my routing algorithm) all traffic through different proxy servers. Let's say I have one host, with many users, connected to my VPN. I want to route all ...
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Why is this static route not taking effect?

Original Question I am running Ubuntu and network manager. I have two different interfaces, eth0 and eth1. Network manager has (as far as I can tell) correctly added this manual route: ~$ ip route ...
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How does Linux handle 2 identical destinations in its routing table?

I have this is my routing table (in that order): 10.3.68.0/22 via 172.16.100.9 dev vlan4 10.3.68.0/22 dev eth3 proto kernel scope link src 10.3.69.254 eth3 has ip 10.3.69.254/22. Why does ...
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What are the requierements to sniff UDP packets in a Wireless Ad-Hoc network?

In a wireless Ad-Hoc network, I have two computers which communicates in UDP together from 192.168.1.3 to 192.168.1.5 I have a third computer (192.168.1.6) which wants to listen to the packets which ...
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Policy routing with load balanced ppp connections

This my setup using Debian 6.0. 6. It's role is a proxy server and a load balancer using eight 3G modems. Whenever a ppp connection dials it takes over the default gateway which is ok but it also ...
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How do I configure OpenVPN as a Gateway client for Witopia?

I have the following setup: Witopia SSL account Synology 409 NAS (with OpenVPN and Apache etc) PS3 Mac Apple AirPort router (configured for NAT) Locked IPT-box (using DHCP and NAT traversing) &...
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Local DNS Server Refuses to Ask itself for DNS

I am running Debian 7 and have set up a DHCP and DNS server. Everything is working nicely, except for the server itself not following the DNS entries in BIND. The problem is that /etc/resolv.conf is ...
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Sniffing packets through router

I would like to create a system like this. The user would connect through a wifi network which would reroute all http requests and responses through the network card on a computer thus allowing that ...
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Use eth interface to connect to a router and wlan for the internet

I am currently trying to configure a router to which I connect to (to its web interface) using an Ethernet cable through the eth0 interface. That router doesn't have access to the internet. Now, I ...
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Xen, bridge and multiple IPs on CentOS

There's a new server that is assigned 5 IP addresses. I want to use Xen to run several VMs with various services. This is my first attempt to install Xen, I use this tutorial as a guideline. Stuck ...
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Block specific IP from accessing gateway

Suppose you are on linux internet gateway/router. What would you do to block a client with specific IP using bash script. I prefer something like ./block_client.sh 192.168.1.123 to block and ./...
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Can't ping host from router, but both router interfaces from host

I'm trying to set up Ubuntu Server 16.04 as a router just to figure out how this works and maybe build a home server/router down the line sometime. Problem is, I can't seem to get it to work, not sure ...
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routing between linux namespaces

I have the following network topology using linux namespaces: .--------.veth0 .--------.veth2 .--------. | ns_snd |------------| ns_mid |------------| ns_rcv | '--------' veth1'-----...
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Linux static routing : Ping a private network(Network Diagram Attached)

In the Network Diagram above my aim is to ping 192.168.20.20 from System A. I do not want to configure the router. For that to happen All the traffic to 192.168.20.0/24 should be first forwarded ...
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add route in Linux if sub-net, where gateway is situated, is not configured

I have a PC which has 192.168.1.1/24 configured to eth0 interface. Now if I try to add routes via 10.10.10.254, the ip utility reports that No such process: root@PC:~# ip neigh add 10.10.10.254 ...
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iptables routing incoming IP to another destination IP question

I have a test setup: server1:1.1.1.1 server2:2.2.2.2 client: 3.3.3.3 I'm trying to have client IP 3.3.3.3 do a HTTP request from the 1.1.1.1 server. However I want the 1.1.1.1 server to pass this ...
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Use two NICs for different subnets

In my office I have use a system with two network cards. I want to use both at same time. I have four subnets in my LAN. I want to route two subnets (192.168.2.0 and 192.168.4.0) through eth0 and ...
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Primary network interface in Linux

I have a server box with two interfaces. One of the interfaces is connected to the internal network, another - to external. I have assigned IP 192.168.1.200 to internal interface (eth0). I have some ...
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multiple default gateways for alias interfaces (SOLVED)

Alias interfaces defined in /etc/network/interfaces cannot have multiple default gateways. Unfortunately I would like to use the same interface to access 2 different nets, and I need to define 2 ...
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Share Internet Connection from computer to new router

On my linux computer I have an external wlan adapter which is connected wirelessly to internet (an access point). Now I want to connect my linux computer via ethernet cable to a new ddwrt router. This ...
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Add route from internal network to external network

I am using a box running Arch as my router and firewall (with shorewall). Recently, I tried to add another network onto the system, which failed horribly. After putting everything back where it was ...
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PPTP VPN not working with Linux router

ORIGINAL: I've just switched from an old Linux install (Debian squeeze) to a new one (Linux Mint 17.3) for my router (I am using a full desktop PC with a Linux install as my router). The Linux PC ...
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OpenConnect: Setting default routes

I'm trying to use OpenConnect to connect to my company's Cisco VPN (AnyConnect) The connection seems to work just fine, what I'm not understanding is how to set up routing. I'm doing this from the ...
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What happens to local LAN traffic on linux to non-loopback addresses?

One thing I've never quite understood on Linux is what happens to local traffic that isn't directed at loopback. For example, given the following network setup: [root@pe-323-master ~]# ifconfig eth0 ...
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Routing through iptables

I have this vpn client that touches the routing table and then keeps watching it to exit if it gets touched. It is the kind of setup needed for an endpoint, such as a laptop. I want to use a small ...
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Need help with routing

I have set up a Ubuntu server, that I want to use as a router for my local office. The problem is, that I want to make 2 VPN connections, to remote branches, and then I want to route all traffic to ...
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1answer
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How to create an internal multipath gateway

Basically trying to bend bridging and NATing to my will with quite a unique project. I've simplified what I'm doing below (VM=Kali virtual machine for testing): ZoneX's are network namespaces, ...
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Linux: How to auto-configure IP routing based upon ping results

I've got a linux server with two possible connections to the net: one is a slow, high-latency cellular modem (ppp0), and the other is through fast wifi->broadband (wlan0). The problem is that the ...
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How do I route different users over different OpenVPN tunnels in Linux?

The setup: I have multiple, static-key OpenVPN client/server configurations, labeled "client1", "client2", and "client3" with server/client IPs 10.10.1.1/10.10.1.2, 10.10.2.1/10.10.2.2, and 10.10.3.1/...
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Linux: Is there a IPv6 equivalent to the IPv4 kernel option accept_local?

Since linux kernel >= 2.6.33 the kernel option "accept_local" can be modified: /proc/sys/net/ipv4/conf/${interfaceID}/ accept_local - BOOLEAN Accept packets with local source addresses. ...
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“ip route get” shows wrong source IP address

I have a machine with an interface which has two IP addresses: inet 192.168.1.15/32 scope global eth0 inet 10.10.118.45/24 brd 10.10.118.255 scope global eth0:hosts4 If I execute for example ip -s ...
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Forward ICMP Ping Packets to Interface

I've got a script that listens for ICMP ping packets (containing data payload) and while this works if you run it from command line, it doesn't work in a Docker container because ICMP ping packets are ...
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No “unreachable” response for an outgoing TCP connection when using fwmark and policy routing

I would like to route locally-generated traffic: to a TCP port "A" of host "H" via the interface "A", to a TCP port "B" of host "H" via the interface "B". Interface "B" is sometimes unavailable. ...