the process by which data packets on communication networks are forwarded into the direction of their ultimate destination by routers.

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27
votes
2answers
84k views

Can I have multiple DHCP servers on one network?

This is a Canonical Question about Redundant DHCP Servers. Is it possible to have more than one DHCP server on the same LAN? What are the implications of doing this? What happens if there is ...
34
votes
7answers
20k views

What is “anycast” and how is it helpful?

I'd never heard of anycast until a few seconds ago when I read this SF post. The wikipedia entry on it is quite formal and doesn't really evoke a mental picture of how it would be used. Can someone ...
6
votes
3answers
21k views

iptables - Target to route packet to specific interface?

My home server has two main interfaces, eth1 (a standard internet connection) and tun0 (an OpenVPN tunnel). I'd like to use iptables to force all packets generated by a local process owned by UID ...
8
votes
4answers
2k views

Multi-WAN bonding across different media

I've recently been thinking again about a product that Viprinet provide, basically they've got a pair of routers, one that lives in a datacentre, Their VPN Multichannel Hub and the on-site hardware, ...
5
votes
2answers
1k views

Policy based routing

I found very good article on load balancing at http://www.diegolima.org/wordpress/?p=36.. I could not implement it though as my requirement is slightly different from pure load balancing. We have two ...
5
votes
2answers
1k views

IP Routing - how does it work again?

Can someone explain how IP routing works to me? E.g. if i ping 123.123.123.123, how does each router know which way to go as shown in a trace route dump.
4
votes
3answers
6k views

second ip address on the same interface but on a different subnet

Is it possible in CentOS 5.7 64bit to have a second IP address on one interface (eg. eth0) - alias interface configuration - in a different subnet? Here is the original config for eth0 more ...
29
votes
3answers
35k views

What is the difference between unicast, anycast, broadcast and multicast traffic?

I have never had the privilege of working in an environment that required complicated routing or if it did require it, it was handled upstream of me. I've always used very simple static routing ...
29
votes
3answers
17k views

Tuning Linux IP routing parameters — secret_interval and tcp_mem

We had a little failover problem with one of our HAProxy VMs today. When we dug into it, we found this: Jan 26 07:41:45 haproxy2 kernel: [226818.070059] __ratelimit: 10 callbacks suppressed Jan 26 ...
8
votes
4answers
54k views

How to route different traffic thru different network interfaces (in Windows)

I've searched for details on how to do this but I've been unsuccessful - I wondered if someone could offer up some advice. So, let's say I have 2 network cards (LAN and 3G in my instance), both ...
3
votes
2answers
2k views

Can't ping multihoned Linux machine on non-default interface

I have a multihoned Ubuntu server with a set of interfaces that includes: eth2: 10.10.0.131/24 eth3: 10.20.0.2/24 The default interface is eth2, with a gateway of 10.10.0.1. Here's what the routing ...
2
votes
1answer
706 views

How to configure Routing, VPN and masquerading in Windows?

I need to link a branch office to a new subnet. I'm doing something wrong. I try to be more specific: I have this object virtually connected as follows: GW_U ---- S-OpenVPN ----- OpenVPN-C ----- ...
2
votes
3answers
417 views

Linux router with 4 NICs not working

I'm setting up a Linux based router, with 4 NICs, and I can't seem to convince it to work, despite following steps suggested on various web sites. Each interface is on a separate subnet as follows: ...
1
vote
1answer
5k views

OpenVPN server cannot ping clients

I have OpenVPN set up on a Debian server. Clients can connect, and clients can ping and access resources (Samba shares and intranet) on the server. However, the server cannot ping the client - it ...
0
votes
1answer
565 views

Configure routes in OpenVPN

I am trying to figure out how to setup routing on OpenVPN. I have successful connection between client (OS X Snow Leopard) and server (OS X Leopard Server), and each can ping the other. However, I am ...
7
votes
2answers
805 views

Routing via Cisco ASA is changing TCP sequence/ACK numbers

Our network has a dedicated VPN appliance that sits inside the office network. We have a Cisco ASA with a static route that routes the VPN subnets to the VPN appliance. So a typical request from the ...
5
votes
10answers
10k views

Forward port to another Ip/port

I recently found out that my ISP disables port 135. I have a server and personal computer behind my router. A friend and I are working on a programming project and are running into some sql issues ...
4
votes
2answers
339 views

EIGRP neighbors flapping

I have a EIGRP topology set up in GNS3. It looks like this: The neighbor relationship between R7 and R8 is constantly flapping and I cannot figure out why. Hello timers and time delays are all set ...
2
votes
2answers
1k views

BGP Multihomed/Multi-location best practice

We're in the process of designing a new iteration of our network where we improve resilliency by adding a second datacentre. We'll be adding a second datacentre, with an identical configuration of ...
1
vote
1answer
448 views

Why did my new iptables rules screw up outbound traffic?

I recently set up Tomcat on Port 80 using instructions provided by Werner Puschitz. In essence, I had to execute these two iptables commands: iptables -t nat -I PREROUTING -p tcp --dport 80 -j ...
0
votes
1answer
4k views

Setting a static route for a specific network adapter with two network adapters

I have a virtual windows server 2008 r2 with 2 virtual network adapters, one is part of a domain and the other isn't. When I ping to a specific PC that is part of the domain it connects to it through ...
0
votes
1answer
223 views

Using a CIDR range as a Routed Subnet?

I have a /29 subnet assigned by my ISP, with an SonicWALL office router and a Cisco voice router hooked up to a 'net-rail' of sorts with untagged VLAN switch ports connecting my ISP router's output ...
0
votes
1answer
2k views

Cisco ASA 5505 Voice/Data VLANs not pinging/routing

Hi i am very new to Cisco ASA 5000 series and have two interfaces that i would like to route between, a data network 192.168.69.0/24 and voice 192.168.70.0/24, I have addded both and can ping the ...
0
votes
1answer
229 views

Local server outside: How to access url internal over router?

i have the following problem: i installed a new test-mailserver in our office today and did some port-forwarding on our router to the specific mailserver ports. everything works fine, except the ...
0
votes
3answers
940 views

Policy Routing with Openvpn?

Dear Everyone I am currently using openvpn for normal browsing. However, I have the following services running: a bit torrent client, a web server, IRC and a git server which I would really want it to ...
13
votes
4answers
15k views

How is route automatic metric calculated on Windows 7?

KB299540 explains how Windows XP automatically assign metrics to IP routes: The following table outlines the criteria that is used to assign metrics for routes that are bound to network interfaces ...
0
votes
1answer
6k views

Using DD-WRT to connect to VPN and Forward all traffic of certain devices through VPN

I have been able to setup my dd-wrt router to connect to an openvpn server and route all traffic through the vpn to the internet. This makes it so all traffic comming in from the LAN to the ...
8
votes
2answers
15k views

Where route to 169.254.0.0 comes from?

Running CentOS 5.4 Why do I have route to 169.254.0.0 although it does not appear in Network > Ethernet Device > Route configuration dialog? Destination Gateway Genmask Flags ...
5
votes
2answers
4k views

ip address scope parameter

In Linux, the command ip address add [...] has a scope argument. The man page says that the scope is "the scope of the area where this address is valid". Follows the list of legal scopes: global ...
3
votes
1answer
25k views

Two network interfaces and two IP addresses on the same subnet in Linux

I recently ran into a situation where I needed two IP addresses on the same subnet assigned to one Linux host so that we could run two SSL/TLS sites. My first approach was to use IP aliasing, e.g. ...
3
votes
3answers
2k views

Recommend- XORP vs GNU Zebra vs Quagga

Any recommendations which of XORP, GNU Zebra and Quagga routing software is simple enough to hack and learn?
8
votes
3answers
10k views

Public static ip for vagrant box

I have server (Debian Squeeze) with 1 ethernet card and 2 public static IPs (188.120.245.4 and 188.120.244.5). What I want: Setup virtual box (Ubuntu) with access via static IP (188.120.244.5). ...
7
votes
2answers
1k views

linux routing bug?

I have been struggling with this not easily reproducible issue since a while. I am using linux kernel v3.1.0, and sometimes routing to a few IP addresses does not work. What seems to happen is that ...
6
votes
4answers
287 views

Why don't we see more routing attacks?

So, who remembers the whole "Pakistan kills YouTube" debacle from February last year? Here's an article on the topic to refresh your memory: Insecure routing redirects YouTube to Pakistan The gist ...
5
votes
4answers
6k views

Specifing ip address for outbound connections on a multi ip host

one of my servers (Debian 5.0.6) has two public ip-address on the same interface. This used to work well for months but suddenly it is using "the wrong" ip addresses for outgoing connections. This is ...
4
votes
3answers
5k views

How to configure remote access to multiple subnets behind a SonicWALL NSA 2400

I have a client that uses a SonicWALL NSA 2400 as their firewall. I need to setup a second LAN subnet for a handful of PC. Management has decided that there should be a second subnet even though ...
2
votes
1answer
2k views

OS X 10.8: redirecting locally initiated ssh connections to localhost:22

I need to hack the OS X pf to redirect all ssh connections from an user to this machine. I want, when doing $ ssh google.com to get the same results as with $ ssh localhost ie a connection to ...
2
votes
3answers
6k views

Routing WIFI and LAN for specific traffic

I have two network devices aboard my macbook pro: WIFI (en1): Used for general traffic. Connects to an ip of 192.168.19.* via DHCP LAN (en0): Used for specific traffic. Connects to an ip of ...
2
votes
2answers
3k views

Redirecting to other internal servers based on sub domain

Here is my situation home network, windows machines, 1 external facing IP address (that allows port 80) 1 windows home server always on machine, planning on upgrading to WHS 2011 soon. several IP ...
2
votes
1answer
4k views

How do I setup routing for two companies with different Internet connections on the same LAN?

Here's the setup: Two companies (A & B) share office space and a LAN. A 2nd ISP is brought in and company A wants its own Internet connection (ISP A) and company B wants its own Internet ...
2
votes
2answers
1k views

How to change routing for skype packets?

I can't seem to find a way to somehow change routing for Skype packets. I have following situation: host ha, in lan, runs skype. host ha has gateway "gw1" gw1 has 2 separate network connections - ...
2
votes
2answers
9k views

Routing decision when there are two default gateways on windows

My windows machine has two network cards, both have default gateways. How does windows determine which gateway should it access when sending a packet to a remote endpoint? More precisely, here's my ...
1
vote
1answer
7k views

How to set up routing for RRAS VPN connections

I have a NAT/firewall running DHCP for the LAN configured to forward the VPN ports directly to the Windows 2008R2 server behind the firewall on NIC1. The LAN switch is also connected to the firewall ...
8
votes
1answer
4k views

CentOS, two nics eth0 eth1 with different subnets aren't reachable outside VLAN/subnet

I am having an issue with a CentOS 6.3 box. We have two NICs (eth0 and eth1) in the server which each have an ip from a different subnet assigned, let's say eth0:192.168.1.2/24 (gateway 192.168.1.1) ...
6
votes
2answers
321 views

When to start using OSPF

We have 4 offices in different countries. They are all connected via VPN to each other (i.e. at least one VPN tunnel from each office to all other three). Each office has between 1 and 4 separate ...
6
votes
3answers
2k views

Amazon CloudFront and EC2: Global Load Balancing

We have an app that is going to store and serve up a decent amount of data in S3 to a global audience where latency should be minimized. So, we've been doing tests with Amazon CloudFront and have seen ...
4
votes
3answers
2k views

two gateways / two providers with different ips

I want to route packets coming in on eth0 back over eth0 and the ones coming in to eth1 back over eth1. I don't care which gateway is used for outgoing connections. If i just enter two gateways in ...
2
votes
2answers
2k views

iptables packet forwarding to one of two gateways depending on origin

Given the following installation: old router 192.168.1.1 with NAT forward of tcp port 80 to 192.168.1.10:80 new router 192.168.1.2 with NAT forward of tcp port 80 to 192.168.1.10:80 web ...
2
votes
1answer
3k views

OpenVPN not redirecting all traffic through VPN

I have just finished setting up my VPN, and google shows my IP to be that of my VPN, so this works fine. However, when I log in through SSH to the VPN server, it shows my last login to be that of my ...
2
votes
2answers
3k views

How do you prevent a VPN from exposing your IP when it disconnects?

I want every connection in a Virtual Machine (windows XP) to ONLY use my OpenVPN server, as soon as the connection is lost to OpenVPN, I want to lose all internet connectivity in the VM. Naturally the ...