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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Detect devices connected to my network

Another day, another question ! I am trying to write a script that would monitor my LAN for any new new devices connected to it and if it finds a new device, send me an email. My test network is a ...
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1answer
21k views

How GRO (generic receive offload) works on more advanced NICs?

I am interested in particular answers: Does the NIC with GRO edits/creates TCP ACK or any other packets (or is this feature transparent to receiver/sender TCP stacks)? There should be a ...
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1answer
679 views

Multiple network interfaces and UDP packets distribution

I have a Linux server with 2 1Gb network interfaces eth1 and eth2. If I start 2 clients listening to the same multicast address and each client connects through a different NIC (say client 1 listens ...
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2answers
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Can I have dots in a hostname?

I'm using names like a.alpha for the hostname of my linux box, but it seams that these name are not completely usable. The response of a hostname shell command is correct (a.alpha). But the name ...
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6answers
2k views

How can I restrict SSH access when the source IP is dynamic

I want to protect SSH access to our live web server from all IP's except our office static IP. There are some employees who connects to this live server from their dynamic IP's. So, it is not always ...
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6answers
14k views

Hostnames - What are they all about?

I've recently been "forced" to perform some sysadmin work, while this isn't something that I absolutely love doing I've been reading, experimenting and learning a lot. There is one fundamental aspect ...
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3answers
5k views

Redirect output of mysqldump to scp

I worked with a linux pro years ago who did this nifty trick. He could do a mysqldump but redirect the output to an scp/ssh connection rather than writing to disk. We utilised this quiet a bit where i ...
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1answer
353 views

ip_queue: full on an SUSE application server. What to do?

An application server (SUSE 64bit) that has my app. on it is emitting "ip_queue: full" message and is refusing connection (e.g. can't ping). My app. is an EJB application that uses JBoss5, and it ...
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2answers
6k views

I need a reverse proxy solution for SSH

Hi here is a situation I have a server in a corporate data center for a project. I have an SSH access to this machine at port 22.There are some virtual machines running on this server and then at the ...
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1answer
1k views

Is it possible to reset TCP-connections if interface goes down in Linux?

Today I was trolled^Wasked to implement resetting TCP connection if internet is disconnected, like Windows® does by resetting all related TCP connection when interface goes down. So, question is: is ...
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1answer
226 views

send mails from a php applciation using SMTP to internal exchange server

I have one Linux server which is connected to my local network and also internet in another network. I host some PHP applications on this server. All the PHP applications should able to send mails to ...
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2answers
7k views

Get linux to change default route if one path goes down?

I'm configuring a gateway/router linux box. It is performing masquerading/NAT. The primary Internet interface is a 3G modem, but if that goes down, I would like it to try a different interface ...
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4answers
28k views

multiple MAC addresses on one physical network interface (linux)

Simple question: How can I setup multiple MAC addresses on one physical network interface (linux)? Why? My ISP is checking ip<->mac on GW and I d like to route traffic through my "linuxbox" and ...
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1answer
630 views

traffic shaping for certain (local) users

i'm using ubuntu 10.10 i've a local backup user called "backup". :) i would like to give this user just a bandwidth of 1Mbit. No matter which software wants to connect to the network. this solution ...
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2answers
274 views

Hardware, network infrastructure for runnng gaming server nd on VirtualGL

Foud nice project VirtualGL (http://www.virtualgl.org/). Tried to run 3D fames (EVE Online, Prototype) on server and display the output on thin client using 100Mbps network. Server: Gentoo Linux on ...
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2answers
5k views

Busybox, netstat, no -p

I have an ultra old (don't ask why) BusyBox (BusyBox v1.01 (2008.12.19-21:31+0000) Built-in shell (ash)) on my DreamBox. I would like to find out which process opened which connection using netstat. ...
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1answer
753 views

Postfix as mail relay for web servers?

I want to set up Postfix to relay mail from a group of webservers. I would like to limit senders by IP so I can restrict the box to only my webservers, so I don't have an open relay and don't have to ...
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1answer
72 views

Machine only responds to network requests from machines it is pinging

I have two machines. WOPR: Ubuntu server edition 10.10 LTS 32 bit Adam Selene: Windows 7 home premium 64 bit / Ubuntu Desktop 10.10 LTS 64 bit I want to be able to SSH from Adam Selene to WOPR, so I ...
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1answer
1k views

What do I need to do to set my computer as Default Gateway?

We are trying to put together a box with dual LAN cards (let's say Outer and Inner), where the Inner LAN card is supposed to act as a default gateway on the network it is connected to. This box is ...
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1answer
80 views

Need to resolve three different netowrk

I have three networks viz 10.0.0.0/8,172.16.0.0/18 and 192.16.0.1/24. I have a watchguard router,which has Lan IPs, 10.0.0.4,172.16.0.1 and 192.168.0.1 and routing enabled for these networks in this ...
29
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2answers
44k views

How to reduce number of sockets in TIME_WAIT?

Ubuntu Server 10.04.1 x86 I've got a machine with a FCGI HTTP service behind nginx, that serves a lot of small HTTP requests to a lot of different clients. (About 230 requests per second in the peak ...
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2answers
417 views

Using linux server as router for network

I would like to setup my Debian Lenny server as a router for my home network using iptables, but so far have been unsuccessful. Below is a diagram of the desired network architecture INTERNET - ...
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3answers
1k views

How to find the real IP to which IPVS is routing a virtual IP

I'm trying to find a problem server hiding behind a virtual IP (using LVS/ipvs). I've got a test program that sends requests to the virtual IP until it gets the bad response, but how can I tell to ...
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3answers
2k views

How do I remotely invoke an xterm on a SUSE Linux Enterprise Server 11

I need to invoke an xterm on a SLES 11 machine (machine A) from another SLES 11 machine (machine B). Currently it doesn't work. So I decided to test some stuff. On machine A the following works: ...
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2answers
2k views

Untangle VPN setup, how to see internal addresses?

So Untangle is setup as the default gateway at 192.168.100.1/24, it is the authorative DHCP server issuing addresses from 192.168.100.100 to 192.168.100.200 and is successfully connected to the ...
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1answer
9k views

how can i add new user in vnc viewer configuration file…?

I have problem to connect my remote redhat linux Server from my desktop pc having Microsoft xp OS using VNC Viewer.I can access the linux machine using vnc through root user with the command ...
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1answer
330 views

Linux DHCP Server - Interface Association

I have a question about the dhcp server on linux Basically my server has 2 interface cards eth0 : 192.168.2.201/255.255.255.0 eth1 : 192.168.4.1/255.255.255.0 eth1:0 : 10.1.1.0/24 On this server ...
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1answer
186 views

Setting up NTP on 2 Linux boxes and one OpenBSD box

I have been tasked with getting an NTP client working on two Linux machines and an OpenBSD machine. The machines are arranged like this: NTPServer / \ / \ L1 L2 ...
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5answers
10k views

Override DHCP hostname on RHEL5/CentOS/Amazon Linux

I'm running Amazon Linux (based on RHEL5) on EC2. I have my own domain name pointing to the instance's elastic IP. Amazon auto-assigns the instance a generic (and not visible on the Internet) ...
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2answers
718 views

Can't view a Ubuntu PC on the network, can't access apache on it, can ping and use samba share though.

I thought that it was because of two machines on the network having the same hostname, and hence asked this question. But it did not resolve the problem. The machine responds to my pings. But when I ...
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1answer
59 views

OpenVPN Client Issue

We have a call centre setup with an ubuntu server as a DC box. We need to access our clients internal application . They have provided us openvpn keys. I am confused how can i have all 120 users ...
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4answers
2k views

Client Side IPTABLES rule to allow active ftp

What iptables rules do I need client side to allow active ftp. I currently unable to connect to ftp via active mode when iptables is running, however if I stop IPTABLES everything works fine. Passive ...
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3answers
5k views

What do “Unknown SSAP” and “Unknown DSAP” mean in tcpdump?

While trying to fix a problem with intermittently losing internet connection on a machine with a wireless connection to a router, I ran tcpdump and noticed packets with "Unknown SSAP" and "Unknown ...
6
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1answer
8k views

Killing CLOSE_WAIT sockets without killing parent process on Linux

Tomcat is leaving me with CLOSE_WAIT sockets which ultimately saturate the maximum number of connections. I've tried many methods in my client and server code to get rid of these to no avail, ...
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2answers
1k views

Linux IPv6 loopback routes getting automatically added

We have a router running Debian Lenny that has been happily routing IPv6 for several months. Our upstream has advised that our address range is changing, and both are currently operational, so I ...
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3answers
295 views

Need solution for linux box with two ethernet cards

I need a solution for the problem for the project work. We have devices, servers and clients working where each device shall have two ethernet cards installed in them. While communicating all the ...
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2answers
130 views

substituting for a router in a closed virtual environment

Just a quick question, how can I create a substitute for a router in a vmware esxi environment containing several windows and linux servers on two seperate subnets? I would like to use redhat as the ...
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2answers
819 views

redundant network handling in linux box

I need your help very badly. I have give a solution for the requirement. I'm struggling for 5 days to get one. Requirement is to get a solution for redundant network in Linux systems. We have ...
2
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0answers
995 views

StrongSwan - Windows 7 0 IPSec IKEv2 connection problems

I am trying to configure a roadwarrior scenario between a linux box with StrongSwan and a Windows Box with Agile VPN. I successfully configured my StrongSwan and my Windows box to connect. The Windows ...
0
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2answers
882 views

Linux/Samba: Broadcast Linux server name on the Windows network?

In order to test my web development work, I've setup a Linux VM on my computer. I'm using Adapter Bridging (instead of NAT) so that I don't have to worry about setting up port forwarding. It works ...
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2answers
1k views

How to configure smb.conf file for samba share in centos 5? [closed]

Iam new to the samba, so can anyone please give basic information to configure smb.conf. And also how it provides permissions and authentication?
12
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2answers
9k views

PXE Booting Virtualbox guests in internal networking mode?

I am not sure if this is just specific to my distro's packages or is a vbox limitation. So, any help would be appreciated. Ok, so I have a network of VMs, with one VM acting as a NAT for the other ...
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1answer
1k views

Linux Firewall Rules

I've configured firewall rules using iptables. Outbound packets are being blocked. It seems like outbound packets are enabled. Does the use of bonding change anything, or do I just have incomplete ...
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2answers
489 views

Is there a way to trace what's sending gratuitous arps?

We have a box that's just started acting up and we're not really sure why. It has IP address (dummy examples) 199.199.199.1 on eth0, 127.0.0.2 on eth1, and 199.199.199.2 on eth1:0. Recently, for some ...
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2answers
40k views

Linux e1000e (Intel networking driver) problems galore, where do I start?

I'm currently having a major problem with e1000e (not working at all) in Ubuntu Maverick (1.0.2-k4), after resume I'm getting a lot of stuff in dmesg: [ 9085.820197] e1000e 0000:02:00.0: PCI INT A ...
2
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1answer
221 views

Consumer board for 4* commodity cluster in tetrahedral back-to-back GB-lan topology

I'm not very sure what consumer board to choose for such a configuration. Im planning to build one or more "Beowulf-like cluster" (starting with one for testing), one such cluster consists of four ...
0
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1answer
338 views

Cannot telnet my computer

A service is running in my system (redhat linux) which opens the port 9000. When i do # telnet localhost 9000 it says, Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape ...
0
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1answer
741 views

How to whitelist range of MACs in 75-persistent-net-generator.rules?

I have a Debian Squeeze (2.6.32-5) guest in KVM that has all virtio network interfaces, and their MACs are apparently blacklisted by udev as per /lib/udev/rules.d/75-persistent-net-generator.rules ...
6
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3answers
6k views

How to see on Linux what network interface and source IP address is used for a route to a specific destination host?

If I have multiple network interfaces (here: 2) on a Linux machine (here: Debian Lenny). How do I see, over what network interface (NIC) a route to a specific destination host is going and what source ...
0
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1answer
339 views

SFTP with Qwest DSL and Static IP

I've poked around a bit and elements of this question are answered here but I'm still not sure what to do. Here is my situation. I have a SUSE Linux box that I want to be an Internet-facing SFTP ...