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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IPv6 MTU and MSS ignored in LAN?

I have a server with a (sixxs) IPv6 tunnel and a local network behind it. The tunnel has MTU of 1470, and a prefix with this MTU is advertised by radvd, and picked up by the local client: root@host:~#...
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56 views

Need some explanations on iptables appended rules

Here are some rules that I append to filter table, and I list the added output related to each one: $iptables -A INPUT -i eth0 -j ACCEPT and the output is: target prot opt source ...
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1answer
884 views

Ubuntu 11.10 on VMware Player - No network behind proxy

I have VMWare Ubuntu 11.10 guest hosted on Win7. When behind a proxy, I am able to browse with chrome / firefox but all other network activity does not work (i.e. curl, system update, apt-get, etc.) ...
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4answers
4k views

How to change persistent-net-generator.rules to be PCI bus dependent and not MAC based?

I am using CentOS 6.2 with VMware. I often have to clone my systems. Every time I clone it is adds a new rule to 70-persistent-net.rules file like so. SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ...
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2answers
8k views

How do I put a bridge on top of a bonded interface?

I'm setting up a Ubuntu Server 11.10 box with multiple Ethernet interfaces that are bonded for redundancy. I'm planning to use it as a KVM host, so I'll need a network bridge. To accomplish this, I ...
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1answer
79 views

Networking debuging [closed]

How to systematically find culprit behind loss of internet in linux? I do know that to to download files/access webpage/use ssh/etc , there are several layers of communication made: application,...
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4answers
3k views

How can I troubleshoot Linux router/firewall forwarding performance with Intel 10 Gbe?

We have a Linux firewall with two outward facing 10Gbe adapters (Intel 82599EB) and one inward facing 10Gbe adapter (Intel 82598EB). The problem I'm experiencing is that the firewall will only ...
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1answer
262 views

Server behind DMZ firewall won't respond

I have a DMZ server set up to forward specific ports to a couple of machines. The intended behavior is for me to send a request to the DMZ on a specific port, and have the machine that's inaccessible ...
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1answer
513 views

Verifying 10gbe peer to peer settings

I attempted to get some help with this question a few days back: Peer to peer connection over SFP+ Passive 10Gbe cable It was however closed as a duplicate. Now I have setup the physical connections ...
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2answers
574 views

Linux does not get IPv6 default gateway from Cisco ASA5510 on autoconf

My ASA 5510 has the following configuration for an interface. My Ubuntu box (2.6.35) connected to this network will correctly autoconf an IPv6 address, but it will not set a default route. interface ...
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0answers
265 views

tcng & tc hiercharchy

Let me explain what I'm trying to do, we have one 10Mbps line coming in, we want to divide that up into 3 3Mbps sections, which are defined by each subnet, then in one of these subnets we have ...
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2answers
1k views

IPv6 configuration SIOCSIFADDR file exist

I am configuring IPv6 address in a Debian machine, and this is what I have in my interface file. auto eth0 iface eth0 inet6 static pre-up modprobe ipv6 address 2001:23:207:141:0:0:0:0 ...
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2answers
5k views

Unable to ping, although can download packages

I've installed Debian Squeeze on a Dell PowerEdge server. However, I'm facing some problem with configuring the network. Although I can ping machines inside my network, I'm unable to d0 so outside the ...
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2answers
238 views

Ubuntu two internet uplinks - how to respond to all

I have an Ubuntu 11.04 server attached to multiple internet connections. My problem is that I cannot get it to reply to pings (and any other requests) from both IP-s, only for the IP I specify the ...
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2answers
2k views

bonding driver broken on centos6?

I have a server with minimal installation of CentOS6 64bit (minimal option from the installer). The bonding driver does not seem to work correctly. The output from /proc/net/bonding/bond0 is: Bonding ...
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1answer
11k views

Kill Tcp Connection

Greeting, I am testing application on linux, and we have a bug related to the database connection, since the database connection cannnot be restarted and it's on a remote machine, I would like to ...
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2answers
1k views

use linux iptables to forward lan traffic to bypass a broken gateway device?

My client's lan includes two soho routers, one of which is a Cisco RV042 and the other of which just died. Each of those routers was connected to an ISP provided router (Cisco IAD series) which ...
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1answer
121 views

Launch application to linux console on startup

I have a small router without a keyboard and mouse, and I'd like to have it display network statistics using "jnettop" whenever the machine is booted up. How can I get the machine to display this ...
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3answers
510 views

Strange network traffic on my dedicated server. How to find out what is causing it

I noticed a trange outgoing traffic in my dedicated server. I'd like to know how could I find out what is the reason to this. One day traffic One week traffic As you can see, there are bursts of ...
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2answers
72 views

Is it safe to call ip address add from more than one process at the same time?

I have a service which binds many NBD servers to a network interface at startup, each with their own IPv6 address. In order to do this, the addresses first need to be added to the correct interface. ...
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0answers
878 views

Fedora join to AD DS (svr 2008): NT_STATUS_INVALID_COMPUTER_NAME

I have been attempting to join my Fedora machine to my 2008 AD DS domain (testdomain.lcl) for some time now. I have followed this article: http://weblog.bignerdranch.com/?p=6 But with no luck. I ...
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1answer
2k views

Configuring Ubuntu for Global SOCKS5 proxy

what is the best way to configure Ubuntu to use a SOCKS5 proxy for all network traffic? Server is ubuntu server. I want to push all outbound traffic through the proxy (apt-get, http, https, etc). ...
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222 views

Server is not reachable because it was setup as Static IP. Must requires DHCP mode [closed]

ISP provides Static IP. Based on MAC address, so that forever the end user have Static IP (to do mail/www servers) Step 1: So as a user we purchased this module called Static IP using MAC address ...
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0answers
367 views

Configure OpenSCEP to grant certificate requests automatically

I am trying to setup an OpenSCEP server that can grant certificates automatically instead of me running scepgrant command every time there is a new request? Can someone let me know how to proceed with ...
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1answer
517 views

Apache2/Shibboleth TCP connections stuck in CLOSE_WAIT

I run an Apache2 server which uses the Shibboleth daemon (shibd) as federated authentication module. Certain server connections using Shibboleth seem to stick permanently in CLOSE_WAIT state. tcp ...
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3answers
4k views

Terminating MPLS vpn on Linux

Is it possible to terminate MPLS vpn connection on Linux and how? On my side Linux box has fiber ethernet interface and has fiber plugged in. We do not have any other router etc.
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5answers
280 views

Finding malicious network usage in a LAN

I manage a small LAN (30 computers, mix of Linux, Windows, and Macs). Transferring a 100MB file to a local server (i.e. in the office, not on the Internet) used to take me about a couple minutes, but ...
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3answers
829 views

Load balancing for webservers (with state sync)

(I've looked at other questions, I don't think any of them cover the same stuff as this) I'm looking at a load balancing solution for our farm of webservers. We currently use Cisco CSS11000 series ...
2
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1answer
320 views

Simple Internal DNS Set-up

I have a few domains pointing to my router which then forwards them onto a server within my firewall. The server is running apache2 and everything works well - my website pops up. I have set up a few ...
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1answer
663 views

xenbr1 dissappeared after server reboot

I'm running a Xen 3.0 server and after rebooting it, the xenbr1 networking bridge never came back. Both eth0 and eth1 are running fine and all the IP addresses are present, however it looks like it ...
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2answers
357 views

postgres fallback to standby server, switching ip address, clear ARP cache

I'm using a hot standby server for my postgres database. I've assigned a virtual ip address to the server. In case of a failure I'm switching the virtual ip from the master to the hot standby server. ...
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2answers
1k views

Multihomed ubuntu inbound connectivity issue

I have a multi-homed system (Ubuntu server, 11.04) where eth0 is lan and eth1 is wan. There is internet connectivity through both, but via different routes. When the system boots, I cannot connect to ...
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1answer
4k views

What is the difference between MULTICAST and ALLMULTI ifconfig ifconfig flags

What is the precise difference between the ifconfig flags MULTICAST and ALLMULTI? Also How do I change the default flags under Ubuntu?
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2answers
676 views

creating a VIF or a Chunking beetwen eth0 and eth1 in order to have only a network interface made by the bridging of them

i have a linux server (RHEL5) inside an HP Enclosure system, i would to create a bridge or a VIF or a chunking (sorry because i am a newbie in this operation) able to hide eth0 and eth1 as two ...
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1answer
703 views

Site-to-Site VPN between a Cisco router and a Linux box

SITE A A Cisco router (877W), configured for incoming VPN IPSec client connections Some servers, in a 192.168.0.0/24 network SITE B A Linux box with a physical NIC and a vpnc client (tun0/30.30....
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2answers
285 views

How can I set the MTU for just one remote server in Linux?

Hi I have a linux server that is behind a customer firewall. I can SSH into it but when I try to scp, the connection dies. I believe this is an MTU issue as described here: http://www.snailbook.com/...
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1answer
2k views

Iptables - forward email ports?

im trying to open some local ports (LAN) and then re-direct them to another server (WAN) using iptables. Here is my config: #WAN allow-hotplug eth1 auto eth1 iface eth1 inet static #Tarjeta red WAN ...
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0answers
1k views

Improving TCP performance over a network with small packet loss

I’m trying to improve my TCP throughput over a “high delay network”, with some packet drops, between Linux machines. I set tcp_mem, tcp_wmem and tcp_rmem to “8192 20530752 20530752”. I set rmem_max, ...
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1answer
365 views

samba not working on one interface

I am going a little crazy trying to get Samba working and would really appreciate some pointers. It's quite possible that I have misconfiged some part of the network configuration too. I am running ...
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3answers
628 views

Linux routing with gateway in different VLAN

On a hosted environment where we do not have control over the routers all we have is a internal network and a DMZ network and a host in each. In the DMZ is a RHEL server running Openswan and ...
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1answer
170 views

What settings should I modify to tune a Linux server for very small yet very high packet rate UDP receive loads?

I am tuning a server that needs to handle small (average of about 50 bytes) UDP packets. The average packet rate is approximately 100,000 packets/second. The data is very burst and can sometimes burst ...
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1answer
9k views

How do I configure a USB ethernet adapter under CentOS 5.3?

I've got a server running CentOS 5.3 (Final; kernel version 2.6.18) which I need to add a 2nd NIC to, initially temporarily, but eventually permanently. I'm not familiar with installing drivers under ...
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1answer
152 views

Can I use routes to influence which interface address multicast listeners use?

I have a server with multiple NICs on it. Each NIC is plugged into a different, isolated network that is serving multicast traffic. I have a program that listens to the multicast traffic on each of ...
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1answer
494 views

ping6 overhead compared to ping overhead

I am testing IPv6 latency from a Linux box, and I noticed this weird difference between IPv4 ping and IPv6 ping: # ping -n -A -q -c 500 speedtest.steffann.nl PING speedtest.steffann.nl (10.3.10.20) ...
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2answers
17k views

How to generate netflow data in linux

We have a number of Linux servers for which I would like to capture netflow data to be processed by a netflow analyzer. I've been spoiled by the ease in which Mikrotik routers allow netflow data ...
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2answers
17k views

How to route network traffic of a host via another host?

I'm not the System Administrator of our corporate network, but I've got two Linux workstations (hosts A and B) with root access to both. Both hosts can see each other fine (ssh, ping, etc works from ...
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3answers
2k views

Broadcom BCM5716 Hangs on CentOS 6 Boot

I have a fresh CentOS 6 installation on a Dell R310 server with a Broadcom BCM5716. The onboard NIC is causing the boot to hang for some reason. Welcome to CentOS Linux Starting udev: udev: starting ...
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3answers
833 views

forward port 3306 from firewalled machine to desktop using SSH?

Here's the network setup: Machine A (my PC) SSH 22 => Machine B (Linode with root access) SSH 21343 => Machine C (MySQL server). I want to forward port 3306 from C through B to A, so I can use SQL ...
5
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1answer
15k views

PREFIX versus NETMASK

I did setup a virtual network interface in Centos 6 copying the ifcfg-eth0 to ifcfg-eth0:1 and changing the appropriate variables. But the connection was unstable. Although one of the pre-existent ...
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1answer
810 views

Linux: ip alias versus iproute

When setting up a web server with multiliple IP-based virtual hosts, I've always used the eth0:x alias notation in /etc/network/interfaces. The wiki on my hosting provider states however that this ...