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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17
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1answer
23k 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 ...
4
votes
1answer
3k views

How to troubleshoot latency between 2 linux hosts

The latency between 2 linux hosts is about .23ms. They are connected by one switch. Ping & Wireshark confirm the latency number. But, i dont have any visibility into what is causing this latency. ...
19
votes
5answers
5k 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 ...
8
votes
2answers
25k 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
votes
1answer
832 views

Port appears open locally but closed from another machine

I am currently trying to set up a Hadoop distributed compute cluster on my network. Currently. my cluster nodes are encountering a problem communicating with my master server. Right now I am working ...
2
votes
1answer
205 views

complicated bonding and network question

I am not a network guy and would like to know how can I setup the below two configurations and their pros and cons: Networking component: -- WAN: Cisco 2970 * 1 Load Balancer: F5 switch 1600 * 2 ...
1
vote
1answer
994 views

stunnel: SSL-to-SSL? (for smtp/imap)

How can I configure stunnel to accpet SSL connections, and connect then to an SSL port on a different server? Here is my setup: Our ISP's server, "Mail Server", supports smtp/imap over SSL. (Not ...
0
votes
2answers
2k views

How to route UDP traffic from one public IP (linux) to another public IP(Windows)

I want to prevent direct access of my Windows Machine and want to expose some programs running on it via my Linux Machine (which again is accessible by a Public IP). Is there a way where-in I can ...
2
votes
1answer
352 views

Limiting a process' network access on Linux?

I've been researching how to sandbox processes, and I came across cgroups, which looked promising. I'm not super interested in using virtualization or strace for this, since I want programs to run as ...
2
votes
1answer
1k views

strongSwan ipsec setup, couple of questions

i am trying to setup a IPsec bridge between my home network and my office network. I want to use StrongSwan to encrypt the traffic as IPsec i am trying to follow this guide A brief description of ...
0
votes
1answer
4k views

Openvpn - enabled redirect gateway but can't access any websites

First of all I'm a newbie to servers but not to stuff like programming so not totally alien to command lines etc. Second, I want to run openvpn on my remote server and connect from my ubuntu desktop ...
9
votes
4answers
1k views

tc u32 — how to match L2 protocols in recent kernels?

I have a nice shaper, with hashed filtering, built at a linux bridge. In short, br0 connects external and internal physical interfaces, VLAN tagged packets are bridged "transparently" (I mean, no VLAN ...
7
votes
4answers
11k 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 ...
4
votes
1answer
6k views

NAPI vs Adaptive Interrupts

Could anyone please explain how two following technologies are used to mitigate interrupt overhead under high networking load? Adaptive-rx/Adaptive-tx, and NAPI; I would appreciate an answer that ...
3
votes
2answers
840 views

Cheap way to detect client round trip times for http

I am trying to figure out a way to detect round trip times for each IP that connects to port 80 on my server. What is a good way to do this? There are far to many connections, and pinging each ip is ...
1
vote
2answers
446 views

How to block internet access to certain programs on Linux

Recently, I have encountered a problem of limiting Internet Access to specific programs. Could anybody recommend a good way of doing that, without using any particular software?
2
votes
1answer
1k views

VLAN tags not shown in packet capture (Linux) via tcpdump

I am adding a tagged VLAN onto eth0: #ip link add link eth0 name eth0.20 type vlan id 20 This results in: #ip link 2: eth0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc ...
2
votes
1answer
5k views

Checkpoint VPN on Linux

I need to setup a Checkpoint VPN client with a customer who gave me these settings: Authentication Type: P12 certificate Password: * Peer Site: IP_ADDRESS They tell me the VPN server is: IPSO ...
2
votes
2answers
386 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 - ...
1
vote
2answers
1k views

Adding ip address to a bridge interface

Is there really any meaning attached for assigning a IP address to a bridge interface. Note : the bridge is created using brctl and then an IP address is assigned to br0 created. Is there any ...
1
vote
1answer
159 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 ...
0
votes
3answers
392 views

Configure gateway for two NICs through static routeing

OK I have two NICs eth0 and eth1. Each over their own default gateway. I can only access the network on eth0 since that is the first NIC to have a default route added. How can I configure my static ...
-4
votes
1answer
321 views

How can I stop Linux from sending ICMP “Destination Unreachable” responses? [closed]

I have a Linux system which has a number of services disabled (for example, telnet). When a telnet client attempts a connection, the system responds with an ICMP "Destination Unreachable". Is there ...
6
votes
5answers
12k views

Can only bring up one of two interfaces

I'm having a bizarre issue with my HP Proliant DL 360 G4p server. It has two gigabit ethernet interfaces but I can bring up only one of them. This is starting to freak me out and that's why I turned ...
3
votes
2answers
437 views

Iptables Forwarding problem

I had initally asked question about sertting up my linux box for natting for my home network and was given suggestions in the thread here. Did not want to clutter the old question so starting a new ...
2
votes
1answer
803 views

Iptables - Forwarding + Masquerading

I am new to iptables and trying to set my linux server as a gateway for my other computers.So naturally I am playing with iptables and needed some help My server has 2 NIC cards, eth0(WAN) and ...
2
votes
2answers
749 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 ...
1
vote
1answer
293 views

Service httpd restart error

Why do i always get the error when ever i reset my httpd: Starting httpd: (98)Address already in use: make_sock: could not bind to address [::]:80 (98)Address already in use: make_sock: could not ...
1
vote
2answers
742 views

Intel igb driver packet loss on Debian Linux 6.0

I am running Debian Linux 6.0 (2.6.32-5-amd64). My network NICS are Intel 82580 Gigabit running with the IGB network driver version 3.3.6 (firmware version 3.2-9). I tested the performance and I ...
1
vote
3answers
492 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 ...
1
vote
2answers
510 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 ...
0
votes
2answers
187 views

AWS VPC + IPtables + NAT: Port Forwarding is not working

Yesterday, I posted a question here but I think was not clear enough in my words. BTW, This question is not a duplicate. I have AWS VPC Setup as below. GOAL/PROBLEM: SSH to Server A from internet. ...
0
votes
2answers
48 views

IPtables: Forward port to another host is not working

I am trying out something so this is my test setup: Setup: I have AWS VPC with a public and private subnet. I have a host in public subnet with a public IP address (say Host A) I have a host in ...
0
votes
1answer
1k views

Sub-interface already in use on another host - brand new interface

I created a sub-interface on a RHEL box, eth0:1, and copied the eth0 config and changed all the settings to reflect eth0:1 and the IP address. However, when I issue ifup eth0:1 I receive this error: ...
0
votes
1answer
1k views

Can't connect or ping to internet from my device using crossover ethernet [closed]

I followed this post to connect my Raspberry Pi (an ARM-based computer) to my PC via crossover cable to use wifi connection of my PC (openSUSE 11.4): (UPDATE: now I have openSUSE 12.1) ...
0
votes
2answers
813 views

Hosting websites on a public ip routed via a private subnet using one Linux machine as both router and server

I use Ubuntu server as router, NATing router and webserver. The server is connected to ISP with a public /29 subnet. Also I host some important websites on it. I asked the ISP to provide ipv6 address ...
0
votes
0answers
253 views

Fowarding port in iptables to internal server

I'm running cPanel/WHM with ConfigServer Firewall (csf). I want to forward port 8080 on my webserver to an internal server with an IP of lets say 10.1.1.1 thats running a webserver on port 80. How ...
0
votes
1answer
255 views

openvpn: network and ports

I've managed to setup openvpn in a test server, configuring the PKI and distributing certificates to test client machines. I can ssh from the client machines to the openvpn server using the IP of the ...