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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Http Requests: how to identify a machine using multiple IP addresses

I have an http server. Is it possible to identify a machine, which is making http requests to my http server using different IP addresses? In other words, is it possible to identify a machine, by ...
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20 views

Routing private IPv4 addresses internally

I have the following set-up involving two KVM hosts and numerous virtual machine guests on each. The guests communicate to each other on both hosts via [192.168.216.0/24]. [192.168.216.42] is ...
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16 views

Openvpn stops responding [migrated]

I've been trying to set up openvpn with a vps and raspberry pi. The raspi is natted while the vps is public. I've tried connecting to the openvpn from mint laptop as well, but it's no use: Server ...
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0answers
5 views

Deny DHCP-Requests for specific subnets on specific interfaces

I have a router (Ubuntu 14.04) running the isc-dhcpd-server on the interfaces em2.X (X can be any of the VLANs 2, 3, 4). Each interface has its own 192.168.X.0/24 subnet. Now I have a Windows-Client ...
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2answers
25 views

arp table entry outside configured network

Can someone tell me why do I have arp table entry outside interface network? Server has 2 interfaces, both on the same network: eth0 10.10.34.146/22 eth1 10.10.33.188/22 ip route default via ...
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3answers
71 views

Networking in Linux KVM

I want to know if there is any way other than using linux bridges to interconnect interfaces from two virtual machines ? Since I am trying to run private spanning tree implementation in virtual ...
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0answers
9 views

Test UDP limit on AWS EC2 instance [on hold]

I'm trying to test to see when my AWS EC2 instance will break when processing incoming UDP packets, since they currently don't support UDP load balancing. My main focus is testing high volumes of ...
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2answers
54 views

Linux Red-hat 6 Network manger interface priority

I have a question regarding RedHat 6 Enterprise Network Manager (NM): My Linux is connected to two network interfaces. 1 – eth0: Normal Ethernet which is connected to the company LAN 2 – eth1: An ...
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1answer
39 views

Adding a VLAN to Multiple Aliased (Virtual) Interfaces

I have a server running centOS 4.6 with 4 NIC ports. I successfully set up 2 ports with 32 virtual interfaces to handle my VLAN-untagged connections and have no issues with that side of things. ...
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1answer
19 views

Cannot Access remote CentOS machine using VNC

I am trying to connect to a remote CentOs machine through VNC to get a graphical display. I have followed the steps mentioned in https://www.howtoforge.com/vnc-server-installation-centos-6.5 to ...
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1answer
24 views

Starting MySQL database server: mysqldinstall: invalid user `mysql' [on hold]

i have a problem with mysql on my Raspberry Pi running Linux raspberrypi 3.18.7+ #755 PREEMPT Thu Feb 12 17:14:31 GMT 2015 armv6l GNU/Linux. This is error I have when I run sudo service mysql start ...
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1answer
17 views

Server stuck with default static IP from router and won't set to anything else [on hold]

I'm green when it comes to networking and in need of help. I have a simple ISP modem going into a Netgear router WNDR3400v3. Then I have this server connected to the Netgear router. The Netgear ...
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0answers
5 views

Ubuntu DHCP-RELAY Error

I have a Ubuntu 14.04 server running as a router (4 NICs with IP forwarding turned on). The routing/forwarding component is working fine. However, I now wish to implement a DHCP-Relay/IP helper so I ...
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0answers
12 views

linux as bluetooth pan access point [on hold]

I'd like to set up linux (debian unstable) as bluetooth path access point. I'd like to connect to this access point from an android phone. (I'd explicitely NOT like to use wlan). I'm interested in ...
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1answer
876 views

How to stop a infinite running process(ztail) started by a ssh session after that session is closed

I have a peculiar problem. My server supports multiple ssh session simultaneously, so that multiple admins can manage it simultaneously. We have a command which calls ztail to show the compressed log ...
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0answers
15 views

iptables, after specifying an interface to drop traffic it drops all traffic of all interfaces

We have currently the situation that one interface (eth0) is linked to the internet. and we 2 other devices (eth1/eth2) for management purposes. Now the idea is to block off eth0 completely from the ...
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1answer
46 views

trouble opening port 8080 on rackspace dedicated redhat linux

I have a server running apache on port 80, and I'm trying to setup nginx running on 8080 to setup/test nginx setup before switching out apache for nginx. I've never had issues opening a port before, ...
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1answer
13 views

Virtual interfaces with different MAC addresses

I try to figure out how to set up two logical network interfaces (at one physical interface) with separate MAC addresses on a Linux machine. My first attempt was to use macvlan which seemed to work ...
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2answers
44 views

How to use a server as a “tunnel” in between the clients and the router, in a small network?

Consider a small network with 1 router (192.168.1.1) and clients (192.168.1.x). The router (OpenWRT) provides Ethernet LAN and WiFi for the clients, to connect to the Internet. Now, I want to use a ...
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2answers
920 views

VMWare and Turnkey Linux appliance can't access network

I have a VMWare ESXi cluster running many Windows and Linux VMs perfectly. I have installed the Turnkey Linux Redmine appliance, and am having a lot of trouble getting the networking to work ...
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0answers
13 views

How much of Linux's recent TCP bufferbloat remediation also applies to SCTP? [migrated]

I am looking at rebuilding an existing communications sub-system within a shared-nothing cluster. The current message protocol is built on UDP but layers on reliable, in-order delivery and ...
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2answers
4k 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: ...
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4answers
62 views

Linux-Networking: How do I get routing to work with two network interfaces on the same subnet? [on hold]

I have a Ubuntu machine with ip_forwarding enabled. iptables forwards too. I have 3 network cards. eth0 - internet eth1 - client1 eth2 - client2 I want eth1 and eth2 to be on the same subnet, ...
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1answer
21 views

how to change the ftp passive mode ip address for haproxy work as reserve proxy?

I have an ftp server in LAN, address is 192.168.1.11 I used haproxy is because lots of other service need it I put haproxy on my 192.168.1.1 the same machine of our soft-route(ubuntu 14.04) My ...
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1answer
30 views

Why is port 443 (but not port 80) being exposed to nmap when iptables is configured to drop the traffic?

A Debian box is running web services on ports 80 and 443 and iptables is configured to allow web traffic only from white listed ip addresses. A second Debian box (that is not white listed) is using ...
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1answer
48 views

IP Forwarding Issue

This is my first post, so thanks in advance for y'all's help. I'll try to keep the background succinct and relevant. I am running a server on centOS 4.6 for network client testing. I have the local ...
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0answers
35 views

How to deploy single OpenVPN server instance with multiple unique “--config server*.conf” profiles?

How to deploy Single OpenVPN server instance with Multiple unique --config server*.conf profiles as service start|restart parameter ? Would you please share any tips to run one single Openvpn server ...
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2answers
29 views

How to configure network interfaces for three NIC cards all on three different subnets

I am setting up a cloud environment on Ubuntu and I am running into an interesting problem. Out of the box Ubuntu (all linux really) doesn't allow you to specify more than one gateway in ...
10
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3answers
14k views

What is the correct way to open a range of ports in iptables

I have come across articles advising for the following: iptables -A INPUT -p tcp 1000:2000 -j ACCEPT And others stating that the above will not work and iptables only supports multiple port ...
2
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0answers
41 views

When is route lookup performed when a packet flows through iptables?

Iptables is often illustrated using diagram I fail to understand when route lookup (routing tables) is performed: inside the "Routing Decision" grey boxes? If so, does it mean a packet is routed ...
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4answers
7k views

Can't start CentOS 7 “network” service

I Can't start CentOS 7 "network" service after disabling and removing "NetworkManager" service. When I check the network service status, it comes up with the following error: #systemctl status ...
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1answer
61 views

Reverse zone not working with BIND9

I'm trying to configure a DNS server in UBUNTU 12.04 with BIND9 service.I'm able to successfully configure the same and the when I'm executing nslookup command it works well.However,the host command ...
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0answers
14 views

Setting up LDAP to authenticate users in data center

I'm a newbie to linux and networking. Somehow I'm assigned to research the tasks of setting up the authentication for users to login in from local office to data center. Here's the hypothetical ...
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1answer
1k views

Infiniband port status UP but can't open UMAD port ((null):0)

My system has 2 infiniband devices, one of which has both the ports up. $> ibstatus Infiniband device 'mlx4_0' port 1 status: default gid: fe80:0000:0000:0000:0002:c903:000f:0a9f ...
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0answers
27 views

CPU usage of server extremely low and webpage load time high?

On a weekday at a time where very few use the optimized website on the server, the time for the page to completely load excluding 3rd party advertisements is about 0.6 seconds to 1 second. Now when a ...
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2answers
131 views

Can't communicate with SMTP server from particular machine

Here is the situation: When I run the following on my local machine, the mail server responds: $ telnet mail.server.com 2525 Trying <mail.server.com IP>... Connected to mail.server.com. ...
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0answers
19 views

vyatta virtual router interface aliasing does not work

I am trying to create an alias on vyatta virtual router. But I do not seem to get it to work. In vyatta we have to just add another address to the interface to add an alias. But the interface is not ...
2
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3answers
3k views

How can I achieve OpenVPN client routing without NAT on Linode

I've set up an OpenVPN network, and it is working properly in the sense that I can access the inner/LAN machines from the remote client. However, my problem is that all traffic from the remote ...
0
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1answer
66 views

Why are eno1 and eno2 in this order?

I've just installed a Fedora 21 Workstation system, and it's reversed the order of eno1 and eno2 from the CentOS 6 system that was on here before. lspci | grep Eth 00:19.0 Ethernet controller: Intel ...
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0answers
20 views

HowTo: OpenWRT routing/tunneling all traffic through an inline Snort sensor

I want all traffic that hits the OpenWRT router redirecting/ tunnelin through a dedicated Snort/Suricata machine, before it leaves the local network. The Snort/Suricata machine should act as an inline ...
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0answers
16 views

IP hashing filter in traffic shaping

I am using a traffic shaping by IP hashing filter. I have Five networks /24 : 192.168.1.0/24, 192.168.2.0/24 .. 192.168.5.0/24 so i create a table with 5 cells and each cells has 256 cells. this is ...
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0answers
24 views

Strange issue with nginx proxy upstream and ssh port forwarding

We were using nginx legacy till now, but we upgraded our system to 1.6.2 recently. We have a port forwarding of ssh as well as load balanced nginx server for two separate internal servers. The ...
4
votes
1answer
75 views

cp -p will preserve times for some files but not all?

I have a source directory on a machine with a bunch of files, all with the same permissions, that I want to copy to another directory, that is mounted via SMB. [tmark@dexter JR09141045 ...
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0answers
22 views

Ebtables to setup forwarding and nat

I would like to use ebtables to perform the following 2 things without using bridge-utils SCENARIO I: I would like to forward all the packets received from eth0 interface onto the eth1 interface. ...
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0answers
11 views

Debian Linux Bridge Mode not forwarding

I am trying to bridge lan adaptor eth0 with the eth1 interface exposed by sierra wireless lte modem. When i create a bridge using the following commands brctl addbr br0 brctl addif br0 eth0 eth1 then ...
2
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1answer
806 views

iftop Shows Lots of Mysterious Connections - Not Showing in netstat

I've just stopped all pretty much all services except sshd on my server (Ubuntu Server 10.04), and when I run iftop I get output that looks like this: 12.5Kb 25.0Kb ...
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4 views

Set up a GRE tunnel over multiple communication channels

I am in a situation where I would like to be able to set up a GRE tunnel running seamlessly over GPRS or Wifi in linux 2.6, preferring of course Wifi whenever available. So on one host I have two ...
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0answers
3 views

How to force a Linux DHCP client to get a different IP address [migrated]

Situation: unconfigured network interface eth1. As root, I give command dhclient eth1, and get an IP. Now I want to change this IP from client side, force DHCP client to get a new address. Answers of ...
1
vote
1answer
25 views

Make VNC available without opening non-ssh ports to the WAN

I have a local network consisting of a gateway router/firewall running dd-wrt, a machine running OS X called mac, and a Debian host named ssh-server. The firewall forwards port 22 to ssh-server. I ...
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0answers
19 views

Multicast works only in promiscuous mode

I'm trying to receive MPEG-TS over UDP multicast transport in Arch Linux. So when I run ffprobe -i udp://@224.1.1.240:6000 it hangs forever with no result. Then I run tcpdump and it shows no ...