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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TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page ...
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13 views

PIV authentication on redhat

I'm looking for a solution, or set of technologies, (etc) - for setting up a mixed (win 7, rhel 6.5) network with centralized login using smart cards (PIV). I know that this is possible using a ...
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260 views

Limiting bandwidth with hashlimit (e.g. kb/s — not connections!) doesn't work, though the man page says it should

According to the iptables-extensions man page hashlimit can do bandwidth limiting: "flows exceeding 512kbyte/s" => --hashlimit-mode srcip,dstip,srcport,dstport --hashlimit-above 512kb/s ...
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368 views

VMware - Broadcom 1000Gbps NIC does not link at 100Mbps to a Cisco switch port

Today we've stumbled on a very awkward situation with our VMWare Server. The server is with ESX 3.5 that has a 1Gbps NIC. We bought a brand new managed Cisco Linksys switch with 10/100Mbps interface ...
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22 views

Can I route traffic destined for a local interface out another interface?

I'm trying to set up a testbench for a transparent device (called TD from now on). The goal is to make sure it forwards and logs correctly. I need to use just 1 machine + the TD in the test bench. ...
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22 views

Massively large number of packets dropped by interface

I have a virtual machine on ESXi 5 acting as a firewall for a PBX, it is running vyatta. When I run tcpdump on any interface, I get some ridiculous numbers! e.g. 4 packets captured 402 packets ...
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39 views

Multicast route setup for multiple interface

Currently I have the below eth5 to receive multicast data for 239.1.1.31. It works. $ ifconfig eth5 Link encap:Ethernet HWaddr E4:11:5B:94:E1:F3 inet addr:10.185.2.2 ...
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32 views

iptables - hashlimits, why it calculate all to seconds

I've tried to set 'synflood' limits with hashlimits, those are my snippet of rules: iptables -A SYNFLOOD_CHECK -p tcp --syn -m hashlimit --hashlimit-above 10/s --hashlimit-burst 6 \ ...
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25 views

Will iBGP fix this routing scenario?

I have to firewalls running for a cloud service in a data centre providing HA internet for currently around 40 machines. Each machine is a Linux based router and has it's own 10Gbit feed from ...
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43 views

Proxmox internal network configuration

We have several servers (with one nic) staying in one rack in hetzner. Proxmox is installed on each one, and they are combined in proxmox cluster. The goal is to create network, between virtual ...
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56 views

Automatically acquire IPV6 address in CentOS 6

The network has fixed IPv4 address, and automatic acquired IPv6 address. Does anyone have an idea how to setup? Thanks a lot! I didn't use NetworkManager. The following is my setting, but it does not ...
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15 views

Improbably high bitrate in the output of “iw wlan0 link”

I am trying to determine the bitrate of a wireless connection that uses the nl80211 driver on a Linux 2.6.39 machine. I am actually using a Netlink socket internally, but the effect is the same as ...
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32 views

Port corruption using iptables NAT on Enterprise Linux 6

I am trying to setup a captive web portal redirect on CentOS using the following configuration: This configuration works for the first few packets, but then suddenly the destination port is corrupted ...
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60 views

Linux as gateway with VLANs failing for local network

We have a private VLAN being routed out from a host connected both to it and to our public network. Hosts on the private VLAN have the private IP address of the gateway host (10.2.2.82) set as their ...
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50 views

what is PAT exactly?

In attempt to understand PAT, I've setup the following setup where I have a Linux Router that masquerades from in internal interface to the external. Thus both clients are able to talk to outside ...
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73 views

Connect two servers with OpenVPN

guys, I need a consulting. I need to connect two servers which are located at another places geographically. One of servers is at LeaseWeb, and another is at our office in Moscow. I'm using OpenVPN ...
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243 views

Using ebtables to drop packets out of bridge and route via Tinc VPN

We have a bridge set up on Ubuntu to link our LAN to our gateway which is on the same subnet. We need this to be able to control the traffic and are not currently in a position to change subnets so we ...
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98 views

Receive errors counter in /proc/pid/net/dev

Can anyone explain what gets reported in /proc/pid/net/dev in the receive "errs" column: $ cat /proc/1372/net/dev Inter-| Receive | Transmit face ...
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148 views

How to use wvdial instead of network-manager in Debian

I would like to get rid of network-manager as it seems to be too magic for me. However for the life of me I cannot figure out how to connect my UMTS-stick using wvdial (network-manager has no ...
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62 views

How can I set ntop not to shorten host names?

With most screens in ntop, there is a list of hosts. Unfortunately, in almost every one, the host name is shorted, for some reason. When the host names follow the company standard, this results in the ...
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63 views

Broadcast across a VDE switch

I created a simple VDE Switch as per: http://stackoverflow.com/questions/2082722/how-do-i-create-virtual-ethernet-devices-in-linux To paraphrase that question, the setup is: sudo vde_switch -tap ...
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113 views

Peer to peer ipsec tunnel - virtual network interface

I'm trying to create an IPSEC tunnel between two machines (not between two networks). Using ipsec-tools, TUNNEL mode. I think I can cope with all those add and spdadd, but how to create a virtual ...
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348 views

VirtualBox - multiple guests, each with a single bridged adapter?

I am running a dedicated server (located at Hetzner, Germany) that runs VirtualBox in order to virtualize several services accross multiple virtual guests. Those guests are supposed to communicate ...
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95 views

What is the meaning of the QUEUE in arptables

I use the nfqueue target of iptables in order to get packet to the nfqueue and do some business rules on them. iptables -A INPUT -p tcp -j NFQUEUE --queue-num 0 I need to do the same on arp reply ...
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579 views

Arp request is not resolved

On my machine, I have assigned ip addresses for two interfaces which are connected through a cable. They are connected with 10G ports. When i tried to ping the two addresses, ping was not working. ...
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129 views

linux netfilter h323 module

In my system There is a Polycom HDC7000 video conferencing device and a VVX1500 ip phone. Incoming connection: Src:Any - Dst:ExtIP1 - Srv:Any -> DNAT to-destination IntIP7000 Src:Any - Dst:ExtIP2 ...
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454 views

why ping6 fails if tcpdump shows ICMP6 request/reply traffic?

I'm having a very strange problem with IPv6 pings on OpenWRT (fon-ng firmware with IPv6 enabled) and hoping someone can help with investigation. In short - wpan0 interface with address aaaa::1/64 is ...
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172 views

Attempting to DNS resolve / relay an IPv6 address for a host

I have a network switch doing IPv6 DNS relay to a Linux box (3.0.4-gentoo #7). The packets (DNS request) are arriving fine at the Linux box. Where I'm stuck now is how to resolve those, either by ...
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122 views

Connect to Orange interface in IPCop

I am using IPCop with a red-green-orange configuration. I am trying to access my webserver on the orange interface, from a computer on the green interface, both of which are inside my firewall. When ...
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196 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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430 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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199 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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528 views

I am not able to ping the IPv6 address asigned to the interface on CentOS 5

I have assigned a stativ IPv6 address to eth2 interface and I am not able to ping it. Here is the configuration setup done in /etc/sysconfig/networking/device/ifcfg-eh2 # Intel Corporation 82546EB ...
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815 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 ...
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6 views

Remote jmeter-server error while getting the results back after some time

I have a question, I'm using jmeter from my pc that drives a jmeter-server that is installed on a RHEL5.8 my version of java is : [jmeter@sem-osb logs]$ cat /etc/redhat-release Red Hat Enterprise ...
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0answers
15 views

muliple ssid's on same interface

I am working on centos6. I have 1 wifi interface. Can I create a virtual interface and create an adhoc network with it (my 'real' wifi interface is already connected to another ssid). This is what I ...
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26 views

Adding a whole IPv6 /64 block to an network interface on debian

I tried adding a whole IPv6 (/64) block to an interface using ip route add local 2001:41d0:2:ad65::/64 dev lo like described here on my Debian server, but I seem to be missing something. If I ping ...
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22 views

Why are my multicast packet discarded?

I have two boxes and I have some issues when tcpreplaying a pcap full of multicast from one machine to the other. I see the packet incoming on the destination machine thanks to a tcpdump instance. ...
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0answers
11 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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48 views

eth0 NIC Link is Down repeating message in kernel log

I've noticed since few days ago that same repeating kind of messages occurs and I positively can say that nothing was intentionally changed (installed/uninstalled) in that period. here's sample of ...
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16 views

Couldn't load target `DNAT':No such file or directory

Trying to do some ipv6 nat and running into an error from ip6tables $ip6tables -t nat -N IPV6-BRIDGE $ip6tables -t nat -A PREROUTING -p all -d 2600:3c01::f03c:91ff:fe6e:2563 -j IPV6-BRIDGE $ip6tables ...
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30 views

Pinging to google.com from a particular interface

I am connected to the internet via wlan0(wifi) and also have an ethernet port(not connected to the internet). I am looking for some iptables rule / route addition, which will let me do a ping via eth1 ...
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26 views

CentOS 6.5 with Oracle XE in virtualenv

I'm running a CentOS 6.5 with installed Oracle-XE. I created a virtualenv where I run my Django-NGINX-Gunicorn Webserver. Locally I can access XE via SQL Developer but when I try to access the ...
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17 views

Qemu/KVM: packet queueing from/to guest

I am new to virtualization and trying to understand the pakcet path from guest to physical nic and vice-versa. I am partiaularly interested in understanding what are the various queuing points from ...
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26 views

Routing traffic based on source (Linux)

I have two interfaces on my server; eth0, wich has one public IP address; and eth1, on which 3 IPS are attached. What I'd like to achieve is route traffic coming to the public address configured on ...
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24 views

Command “ip rule show” not showing anything

I try to list all routing rules, and as far as I know this should be accomplished with the "ip rule show" command. In my case there is nothing returned (really nothing at all). Why? Could it have to ...
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19 views

Forward connecting IP address to KVM guests

I'm running kvm with iptables configured to use DNAT and masquerading. However the guest machines are logging the host bridge ip not the connecting client IP address. Is there a way to configure ...
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45 views

Configuring VRRP with keepalived on two machines - interaction with proxy arp

Let's assume we have the following topology for our network: Host1------- Router1-------Router2----------Router3-------Host2 and we want to configure vrrp on the two hosts with keepalived so that ...
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29 views

CentOS 6 network failling to connect network after exporting VM from VirtualBox to VMWare Player

I have installed a CentOS 6 virtual machine in VirtualBox and I want to export it and use it under VMWare. But after exporting, network does not work. There are some other interfaces created with the ...
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33 views

VPN route works for browser, but not for Curl

I am using "Cisco AnyConnect Secure mobility Client" to set up a VPN connection. This works just fine for connecting web browsers, but when I tried doing the same connection with Curl I get: About ...