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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Route traffic through internal (VDE) bridge

I have two NICs configured, let's say eth0 with IP 10.0.0.1/24 and eth1 with IP 192.168.1.1/24. IP forwarding is enabled, rp_filter is disabled. I've created 2 tap interfaces and bridged them with: ...
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62 views

How can I set ntop not to shorten host names?

With most screens in ntop, there is a list of hosts. Unfortunately, in almost every one, the host name is shorted, for some reason. When the host names follow the company standard, this results in the ...
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2answers
371 views

Mysterious “fragmentation required” rejections from gateway VM

I've been troubleshooting a severe WAN speed issue. I fixed it, but for the benefit of others: Via WireShark, logging, and simplifying the config I narrowed it down to some strange behaviour from a ...
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0answers
63 views

Broadcast across a VDE switch

I created a simple VDE Switch as per: http://stackoverflow.com/questions/2082722/how-do-i-create-virtual-ethernet-devices-in-linux To paraphrase that question, the setup is: sudo vde_switch -tap ...
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474 views

Always get “SIOCADDRT: File exists” when restarting networking on ubuntu

I have a problem very similar to getting error "SIOCADDRT: File exists" when trying to restart network on ubuntu, but it is not a duplicate for reasons explained below. My ...
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3answers
177 views

How to safely capture or duplicate incoming requests to a web server

We have taken over a legacy web application that we cannot modify (the source code is broken and deployment fails) and we will eventually rewrite. Ideally we would migrate it one step at a time but ...
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1answer
100 views

How do I receive traffic to the public IP of an additional ENI on EC2 Ubuntu?

I've added an additional network interface with elastic public and private ips. In ubuntu I can see the interface getting a local IP from DHCP, but I cannot ssh to the additional public IP. I'm ...
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48 views

How do I figure what process is caching DNS

There seems to be some form of DNS caching on my machine as my networking scripts continue to give gaierror even after a broken connection has been reinstated. There is no nscd installed and dnsmasq ...
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1answer
44 views

how can I change the web server's identity into mine?

Can the web server execute a command in my Linux environment, and the Linux environment treat it as a request coming from me not from the server? In other words, how can I change the web server's ...
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1answer
104 views

Is it insecure to use the following iptable rule for NAT?

I want to setup a VPN server for personal use, so I follow the blog article [1], and it work like a charm. The only thing I am wondering is if the iptable's rule secure, e.g. iptables -t nat -A ...
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2answers
3k views

CentOS 6.4 Missing Network Route on boot up after minimal install

I am testing a server configuration using CentOS 6.4. I do a minimal install and in the process of installing choose eth0 to be enabled at boot and enter a static IP address and gateway. When I boot ...
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1answer
124 views

How can I find the cause of an unknown connection showing in iftop?

I have connections like this showing frequently in iftop: 12.15.127.75.host.nwnx.net => 121.61.153.172 480b 160b 40b I have no idea ...
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2answers
925 views

arp-requests cannot be seen by specific nodes

I create an open ad-hoc wlan by using iwconfig (I have the same issue with wpa_supplicant as well). there are 4 nodes on the network as seen on the figure below. The nodes run ubuntu 12.04 and debian ...
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1answer
77 views

How to run Different congestion control algorithms in FEDORA 17?

I need to use different congestion control algorithms for tcp flow. How can I continue using those flow congestion algorithms from Fedora 11 in Fedora 17?
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2answers
71 views

determine IP for device [duplicate]

I am configuring an eth1 interface on in Red Hat, but I don't understand exactly what the IP address should be. I'm given an IP of 10.237.128.0/25. This means that the NETMASK would be ...
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1answer
224 views

Open source proxy server SSL interception and HTTP header insertion [closed]

I am new to proxies. Can anyone suggest an open source proxy server that supports SSL interception and HTTP header insertion.
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3answers
798 views

Bridging eth0 to wlan0

I'm trying to create the followig setup: +----------+ | Wi-Fi | +----------+ ...
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2answers
99 views

I can't ping my server from certain IP

I have 2 internet connections from 2 different ISPs with static IPs, lets call them A and B. A connects to the server in several ways (ping, SSH, HTTP), while B cannot do anything (ping, SSH, HTTP). ...
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1answer
227 views

FreeBSD 2 network cards

We have server with 2 network cards with FreeBSD on it. 1 card used for internet (works fine) and another one for local network connection (to 192.168.227.0/24 net). When i try to ping gateway of ...
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3answers
4k views

How to “restart” particular network interface on RHEL?

In RHEL, instead of using service network restart command, how can i restart a particular network interface, lets say "eth1", with only one command. "Only one command" because that is the only ...
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1answer
176 views

Which Package has net_tstamp.h?

I attempted to compile the source code here: http://os1a.cs.columbia.edu/lxr/source/Documentation/networking/timestamping/timestamping.c?a=x86;v=2.6.32 However, I got a compiler error: error: ...
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1answer
1k views

How to scan New network card or any other devices in linux

I am trying to add a New Network card into Machine which has Linux installed. But my problem is, I cannot reboot the Linux host to detect the new network card, is there any workaround for this? I ...
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1answer
93 views

Interface ip address discrepancy

This is very strange. Output of ip route show: default via 192.168.1.1 dev eth0 metric 100 192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.10 192.168.1.0/24 dev eth2 proto kernel scope ...
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1answer
129 views

Changing Linux Layer2 forwarding decision?

Are there tools to define in Linux something similar to Policy-based Routing, but on Layer2 level? Usual Linux bridge uses destination MAC to decide, which interface to send frame to. Can this ...
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2answers
170 views

Can I reassign eth1 and eth2 without rebooting the server

Say I have eth0 - my management interface, then eth1 with mac1 and eth2 with mac 2- additional nics running. How can I reassign eth1 with mac2 and eth2 with mac1 and bring them up without the reboot?
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2answers
523 views

Hack Cisco Pix 501 to Run Linux [closed]

Can a Cisco Pix 501 be hacked to run Linux with a similar feature set? Is this possible? Has it ever been done? The pix seems like reliable solid-state hardware and it would be cool if I could run ...
0
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1answer
127 views

Add second IP block to one debian box (one nic) from different subnet than the first block

I have zero networking knowledge, so bare with me please. I got the following: xxx.xxx.199.208/29 xxx.xxx.221.64/27 The /29 IP block is available directly from the network drop The /27 IP block is ...
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2answers
148 views

Why there are always 10% of loss when testing with mtr command?

For example, if I run this command against example.com, with mtr command, I always get 10% of loss, no matter how many time I run, why exactly is 10%? mtr --report 192.0.43.10 HOST: localhost Loss% ...
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2answers
221 views

iptables TCP handshake on Centos 6.0

Here's my iptables script: #!/bin/sh service iptables stop iptables -F iptables -P INPUT DROP iptables -P OUTPUT ACCEPT iptables -P FORWARD DROP iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -p ...
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1answer
384 views

HTTP Keep-Alive puzzle with EC2 Linux, Nginx and Chrome

Please, help to solve HTTP keep-alive problem. Basically, I have amazon-ami linux (v2012.09) on EC2 running nginx (v1.2.6). Chrome (v25.0.1364.99) accesses HTTP page normally, then after about 30 ...
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1answer
73 views

mount point and distributed folder

I have 10 unix servers and in that /home is common in all the unix servers and any update in /home of any server is getting reflected in all the servers. How is this done? and also please let me know ...
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2answers
198 views

Ubuntu Server 12.10: set up network bridge in the initramfs pre-boot environment

In this scenario, I have a machine that boots its root volume off of iSCSI, and it only has a single network interface. If network configuration is done the normal way, then taking the interface down ...
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3answers
194 views

Name resolution behind a proxy

Using Linux (Debian) At my current place of employment I'm behind an ISA proxy server, I'm not in a position to make any changes on this machine. I'm developing software and have set up a virtual ...
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1answer
142 views

Multiple macbooks can't connect to company web server

We're having a very strange problem where 2 macbooks running osx 10.8.2 can't connect to our public facing server on any port. Attempting to ssh or navigate to the web server fails, but every other ...
4
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2answers
967 views

Am I using virtio for my KVM guest?

In one of my KVM guest, when I typed the following command, I get the following /sbin/lsmod | grep vi virtio_balloon 3692 0 So does it mean I am using virtio? Update: When I type cat ...
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4answers
2k views

IPv6 only works after pinging the default gateway.

We now have 2013 and I thought it is long overdue to activate IPv6 on my server. But unfortunately, I ran in some problems. To be honest I only have litte experience with IPv6 So I hope you can help ...
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3answers
182 views

How to access a server from different LAN, through web and SSH via Internet

Here is my scenario: I have a server (with CentOS on it) configured so that it will maintain the users from a LAN with some common requirements. That server will be deployed in different countries on ...
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1answer
47 views

Tracking data sent to remote host over time?

What is a a good way to track over time the amount of data transferred from my Linux server to another host on the internet? https and imaps only
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1answer
260 views

Setup Network with two ISP

Currently I have a network with 1 ISP, a router/modem, Gigabyte Switch and a server. All the clients PC are automatically assign IP from DHCP server from a Router/Modem A. Server A have a fixed IP ...
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2answers
550 views

OpenSSH Can't Connect on Fedora 17

Having trouble SSH'ing to an internal server that is outside of an enterprise level firewall. I have a fresh install of Fedora 17. Here is the command I'm running: ssh ...
2
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1answer
163 views

Bandwidth fluctuations while running java server

We are running a distributed system of java servers (os: linux) doing lot of computation with communication over TCP. While our traffic pattern in not bursty, on some machines we see a fluctuation in ...
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1answer
100 views

Ubuntu Second Wan Interface Card

I configured 3 network card. one of them is LAN card and others are Wan network card. eth0 Link encap:Ethernet HWaddr 00:50:56:00:30:da inet addr:5.x.x.1 Bcast:5.x.x.3 ...
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0answers
82 views

Two Xen hosts with a crossover between and failover public IP between them both. configuration?

I have two servers with Ganeti installed (Xen) I want to be able to migrate the instance between the two servers so the instance's network configuration needs to be host agnostic. The datacenter that ...
3
votes
1answer
171 views

ip command vs route command, what's the difference?

I see both ip and route commands used for configuring the kernel routing tables. What's the difference? It seems to me that the ip command is preferred more. Is it so, and why?
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1answer
79 views

Why can't I reach the LAN side of a slave vrrp router?

I have a dual linux firewall/router setup that is connected to 2 different upstream providers. Internally the default route is a failover using vrrp. The setup looks something like this. The routes ...
0
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1answer
389 views

Keepalived in ring architecture, or other better approach

I have three load balancer (LB1, LB2, LB3) and plan to use ring architecture for active-active setup, e.g. LB1 LB2 LB3 IP1 IP2 IP3 Idea as below: If LB1 failed, IP1 will be floated to ...
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1answer
157 views

IPV6: two interfaces with dhclient

I have eth0, eth1. For each interface run dhclient on default port 546 (547 ?). eth1 does not have connection to the network. If dhclient for eth0 bounds before dhclient eth2 starts the eth0 gets IP. ...
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2answers
573 views

How do I configure dd-wrt to forward IP Protocol ID 50 & 51 traffic to an internal machine?

Please note, I'm not talking about TCP or UDP traffic. Rather IP traffic with the protocol ids of 50 and 51. The point of this being that I can then pass IPsec traffic thru to the internal machine ...
2
votes
1answer
125 views

Linux router: bandwidth of client

I am trying to build a linux router (captive portal) with a local RADIUS server for authentication. I want to log the bandwidth being used by each client on my network. I want to associate bandwidth ...
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1answer
444 views

Setting up bridging for Qemu and routing for OpenVZ (venet) with multiple subnets on Debian Linux

So i've been searching the past couple days trying to figure out the best way to achieve this but still can't get it figured out. I have a debian server setup running Proxmox to host OpenVZ and Qemu ...