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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How to setup VM network such that they all have different public IP addresses

For example, in Azure or Digital Ocean or EC2, we have an option of creating unlimited number of virtual machines. How does each of these VMs come to have different public IP addresses. More ...
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11 views

How to use two NICs [1onboard and 1 lan card] of my server [Ubuntu]? [on hold]

Good day, my scenario is I want to configure both of my NIC so that 2 different networks [192.168.4.2/200 and 192.168.1.2/200] can access my Web server. I jut want to know if it is possible? and How? ...
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1answer
385 views

Using my IPs on OVH server via GRE

I can't route my IPs into a OVH server, can you help me to find the problem? Mikrotik GRE IP: 192.168.55.10 OVH Server GRE IP: 192.168.55.20 GRE iface name: ali1_fr1-ovz1 IP to route from Mikrotik to ...
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0answers
12 views

How to upgrade Ubuntu to 16.04 LTS and not lose network access

When I upgraded one of my servers to 16.04 LTS I had to adjust network configuration (I use interfaces file) and use the new network interface name. I was lucky that the server runs in a VM and I ...
9
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4answers
7k 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 ...
1
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1answer
18 views

DH GEX group out of range

I'm having a sudden issue SSHing into my server: ssh -v --@-- OpenSSH_7.2p2 Ubuntu-4ubuntu1, OpenSSL 1.0.2g-fips 1 Mar 2016 debug1: Reading configuration data /home/paul/.ssh/config debug1: Reading ...
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16 views

How can I make Kickstart chose which build to run, depending on the subnet of the client?

I have 2 possible subnets that systems could be built in using Kickstart, with the subnet of the client directing which build should occur. How could I go about this? I have tried the following %...
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26 views

CentOS 7 connectivity issues

I have a second CentOS 7 box that's having a lot of trouble connecting. Basically, we were running WHMCS, but a domain lookup kept failing. So the issue is IPv6 connectivity. [root@da01 ~]# yum ...
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2answers
4k views

WMI: wmic linux agent query error: NTSTATUS: NT_STATUS_ACCESS_DENIED

Myself new to wmic and keep trying for a long time with default agent query approach. wmic is linux based WMI tool to talk to windows WMI agent. While trying to fetch data with wmic from nt(win7 with ...
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1answer
17 views

TCP retransmission delays - lost acks

Maybe somebody will be able to help me out with this. I'm trying to find out if there is anything that can be optimized server-side to reduce delays in case of packet loss. Environment: Windows 2012 ...
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3answers
34 views

How to get list of all the hostname / DNS of the Linux box

I have a Linux box and I know I can get the list of IP addresses assigned to that box using following command /sbin/ifconfig -a but how to I get the list of hostnames / DNS for that Linux box using ...
2
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1answer
29 views

Close all _existing_ TCP connections on some ports using IPTables?

Say I have a quick network partition test that I'd like to run, like disconnecting two halves of a ReDiS cluster from each other, and I want to use IPTables to temporarily disconnect one group of ...
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0answers
11 views

Pervent connman disable wired interface

I'm running application over Centos 7 using Connman to manage connectivity. I have one issue working in the following scenario: Wired connection is enabled and online, have inet connection in this ...
0
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1answer
46 views

cannot use localhost but 127.0.0.1 works

My usecase is that I manage remote computers using reverse SSH tunneling. This works great as our customer enable the tunnel and I can then log on using it. However, on one machine the tunneling ...
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0answers
5 views

Configure network card without knowing its name [migrated]

I have a domestic headless server that boots from (and has the root filesystem in) a removable USB stick. I install it from my laptop (following this nice checklist) and edit the configuration files ...
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2answers
33 views

How can i set my new ip adress? [Debian / Ubuntu] [closed]

I have my own VPS at OVH and it comes with a default ip address in France. So for geolocation needs, i bought one for in the UK. Now i have Ubuntu server 16.40 running, and i want to set my newly ...
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2answers
53 views

Linux block outgoing traffic to a specific ip without iptables

I basically need to run the following iptables -A OUTPUT -d 169.254.169.254 -j DROP except I cannot use iptables because the program is running in a docker container and I cannot use the --privileged ...
2
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0answers
501 views

OpenVPN sndbuf and rcvbuf

I would like to know what is the difference between the sndbuf and rcvbuf buffer used by OpenVPN and net.core.w/rmem_default or net.ipv4.tcp_r/wmem. What does OpenVPN do when some value a provided ...
1
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1answer
15 views

KVM - Adding public IP over bridge

I am working on setting up a KVM environment and normally I just take it for granted that the networking has been set up. I am running into difficulty getting the public IPs accessible from the VMs. ...
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0answers
8 views

Sar command “sar -n EDEV -f /var/log/sa/sa16 -s 11:00:00 -e 15:00:00”

sar -n EDEV -f /var/log/sa/sa16 -s 11:00:00 -e 15:00:00 I am using above command on Red Hat Enterprise Linux Server release 5.9, and below is the output to that:(Dev error form 11 am to 3 pm). I have ...
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1answer
25 views

Debugging dropped UDP messages on Linux

Here's my setup: I have 1 host that has a 1 Gbit Ethernet connection and 2 hosts with 100 mbit connections (connected to the 1Gbit host through different switches). In a test, I send 1000 1kb ...
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0answers
26 views

Iptables u32 matching nat

I'm currently setting up IPtables to redirect certain UDP payloads to my application. Here is an example of what I have working so far: iptables -t nat -I PREROUTING -p udp -d {IPDST} --dport 27055 -...
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20 views

Same mac addresses discovered in VM for bridges on host machine

I have two bridges on host machine, named br0 and br1 (having different mac addresses). A VM is connected by bridged networking through br0. Now VM is able to ping br0, which is normal. But it is also ...
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6 views

Username lookup for TCP Wrapper

I would like to ask people in this community regarding to TCP Wrapper. My OS environment is below. [root@server1 ~]# cat /etc/redhat-release Red Hat Enterprise Linux Server release 7.2 (Maipo) [...
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28 views

Inherited debian cluster nightmare

Hi and thanks in advance. So my research group at my university inherited an 8 node cluster. Me being the only member who is Linux savvy was given the task of managing it. So to start I'll describe ...
5
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2answers
3k views

Siege: descriptor table full sock.c:119: Too many open files

I am trying to make a stress test in my own server using siege with the following command: $ siege -c 500 myweb.com/somefile.php But I get this error: [error] descriptor table full sock.c:119: Too ...
0
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0answers
36 views

hostapd Wired 802.1x with Bridge

I've got a PCEngines APU running Debian Jessie. I'm trying to configure hostapd to perform wired 802.1x authentication against a remote domain controller running NPS on 2008 R2. I would like 2 of it'...
0
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0answers
75 views

Pacemaker: How to configure default gateway for virtual IP?

I have three nodes and three virtual IP addresses in the same subnet. It doesn't matter which address is assigned to which node. The IPs are public addresses. The nodes are load balancers that ...
0
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1answer
20 views

Cacti generate old graph

I have a cacti system (Version 0.8.8b). The cacti system has been running for a year. I would like to generate retroactive daily graphs, because cacti can't show the old daily graphs. How to ...
0
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2answers
41 views

Load Balancing & High Availability Network Limitations

I'm in the process of coming up with a highly available Apache / MySql group of virtual servers using HAProxy Reverse Proxy & Keepalive. I'm aware that I'm going to be using a floating public ip, ...
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2answers
1k views

What is causing the famous “broken pipe” when I use tmux inside an SSH session?

Scenario1: I SSH from my employer (OSX Yosemite SSH client) to my home server (Debian stable) and (re)connect to a tmux session. If I leave the terminal inactive for a while (~20minutes), it seems ...
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35 views

static network setup still using DHCP

I'm configuring an Ubuntu 14.04LTS server on our internal network. Everything works and runs as expected. Its assigned a static IP, here's /etc/network/interfaces # The loopback network interface ...
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0answers
22 views

vnstat and dstat report different totals

I'm trying to monitor bandwidth going through one of my interfaces, and I've discovered that dstat and vnstat both seem to report different rates... vnstat: [root@... ~]# vnstat -i eth8 -l ...
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1answer
41 views

How to create a HTTPS Proxy?

I have to setup access to a remote API service in which requests are IP-Whitelisted. The problem I have is that my web-nodes are in the cloud and their IP addresses often change. Therefore I want to ...
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2answers
1k 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 properly....
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1answer
4k views

Error while bringing up eth1

I'm getting this error while bringing up my network card: (process:2550): WARNING **: _nm_object_get_property: Error getting 'State' for /org/freedesktop/NetworkManager/ActiveConnection/3: (19) ...
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2answers
59 views

Installing Mellanox ConnectX-2 10gbe PCIe Card on Centos 6

I just installed a Mellanox ConnectX-2 10gbe PCIe x8 Card into my server running CentOS 6.7. On boot, dmesg shows the mlx4_core driver being loaded automatically however I see no eth1 device ...
2
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0answers
49 views

How does AWS configure the 169.254.169.254 address on an instance?

AWS uses 169.254.169.254 as a link local address, which you can use to pull meta data about the instance, ie: curl http://169.254.169.254/latest/meta-data/ How/where is this IP configured on the ...
0
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1answer
35 views

IP Range - Subnet network configuration on CentOS 6.4

I have problems to configure an subnet /25 on an vps with CentOs 6.4 have tried different version. The original eth0 settings are: DEVICE=eth0 #HWADDR=de:8f:24:e9:7b:04 TYPE=Ethernet UUID=64e110dd-...
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1answer
2k views

How to configure VXLAN over linux bridge?

I am using Ubuntu 14.04 which support VXLAN configuration. Currently I can add a VXLAN interface such that: vagrant@ubuntu:~$ sudo ip link add vxlan1 type vxlan id 1 group 239.1.1.2 vagrant@ubuntu:~$ ...
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0answers
16 views

Why would rsync be limiting syncs to ~252Kilobytes?

Here's a head scratcher for you... or at least it is for me. I am transferring a Wordpress site away from WP Engine to an Amazon instance. I am trying to upload the original Wordpress files from my ...
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2answers
59 views

How can I determine which network adapter is SFP+ in CentOS?

I have a server which has an SFP+ module. We are going to utilize this to get 10gb speeds. I have adapters em1, em2, em3, em4. How can I determine which adapter is the SFP+ adapter in Centos 6.5?
2
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1answer
56 views

Possible to force TCP window scaling to a higher value?

Is it possible to increase the TCP window scaling factor on Linux (CentOS 7.2)? I have a long fat network (100 Mbps) from London to Chicago and I'm getting 16 Mbps throughput in TCP on an sftp from a ...
0
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1answer
22 views

Using a VPC from the office vs. VPN from home: Not all hosts are reachable

Here is my situation: Our whole office is VPNed to an Amazon VPC through openvpn. We have 3 VPC subnets: 10.1.25.x (Prod) 10.0.3.x (Staging) 10.0.1.x (build env) While in this office, all is ...
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35 views

How do I reduce private network latency below 0.5ms?

We are migrating from one host to another. Our cluster consists of 10 dedicated linux servers which must communicate on a private network. At the old host we observed latencies below 0.2ms between our ...
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0answers
22 views

KVM/libvirt: NAT forwarding virtual bridge to host bridge

I currently have a VM setup where only a few 'special' VMs are allowed to have outward facing IP addresses and the rest aren't. All of them are configured with two interfaces attached to a virtual ...
4
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1answer
1k views

Passing through RDMA network devices to docker containers

I'm wanting to passthrough infiniband to a docker container so that I can run some high performance apps over ipoib and use rdma. Currently, I'm doing this with xen virtual machines. Now I'm looking ...
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0answers
10 views

Can the VRRP ID of 2 different systems clash (keepalived and cisco/force10)

Since Keepalived and Cisco/Force10 both use VRRP, and use an ID Range of 0-255: 1) Would using the same number in the same vlan cause a issues. 2) Would using a different number in the same vlan ...