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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18 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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366 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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338 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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391 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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9 views

Windows network failing, not present on linux clients

got a really strange one for you all. I have a network setup using a linux machine as a gateway between various network segments (on seperate nic's) and virtual machines (one of which is a mail ...
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20 views

Losing connection to server from several computers

I have a PostgreSQL server running Oracle Linux. In my network I have several workstations each running different OS (Fedora, Ubuntu, Windows). Every once in a while I lose connection from the several ...
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56 views

Shorewall redirect rule only working for some hosts in the same network

I'm trying to use Shorewall's REDIRECT action to intercept traffic destined for the firewall's port 514 (TCP and UDP) to port 5000 (also TCP and UDP), while also allowing direct traffic to the latter ...
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41 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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62 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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128 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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118 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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95 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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102 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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87 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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22 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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57 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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234 views

access tap interface in network namespace across machines

I want to be able to access services running on a TAP interface within a namespace from outside the machine where it is running. I have setup that looks like this - VM1/Machine1 +eth0 : Public ...
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69 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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80 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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269 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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119 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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185 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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74 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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83 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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123 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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380 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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102 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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642 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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163 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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489 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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179 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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145 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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205 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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483 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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217 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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589 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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841 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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9 views

zeroshell unsupported onboard Intel Ethernet I217-V and I210

I recently installed zeroshell 3.0.0 on a machine with a supermicro motherboard that has 2 onboard ethernet cards. It seems that this version of ZS does not support both of ethernet. I've read from ...
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5 views

How to config Squid SSL bump to let Paloalto PA series firewall recognize App-ID

A Paloalto firewall(PA-2050,POS 4.1x) was capable of recognizing the websites which users are visiting(thru http/https) then flag them with a App-ID and apply application control on the traffic, for ...
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5 views

TOS reflect on pppoe tunnel in Linux?

How to perform TOS reflect in Linux? In this case, on a pppoe tunnel through eth0, reflect TOS from each pppoe packet onto the actual ethernet packet going thru eth0. On some nicer routers it's a ...
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14 views

Clients losing stateless ipv6 addresses

I'm having problems with Linux VM's at a certain VPS hoster. Periodically the hosts lose their ipv6 address. They go to 'deprecated' and then disappear completely. On the client side I have checked ...
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0answers
6 views

VPN Connection pooling?

I'm having a problem on PFSense https://forum.pfsense.org/index.php?topic=23914.0 where I can only connect one client with a PPTP VPN to a VPN Server outside out network. PFsense is our firewall and ...
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22 views

Open vSwitch double VLAN tagging is ignored

I'm trying to add a flow to a KVM machine using Open vSwitch 1.10.2 for it's networking, which double tag all traffic comming from one of the virtual machine's ports. I'm using the following command ...
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21 views

Ubuntu server - NIC suddenly loses connectivity

I'm scratching my head. I recently configured a server with two identical Intel NICs inside a DMZ. This morning at around 8:05, I successfully SSH'd in through the internal interface (via my LAN-based ...
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39 views

Linux routing: How to allow a device inside private network to connect a public IP over an unknown network?

Consider following network topology: ---------- ---- (my network) ---- | Device 1 | (.101) | 192.168.191.0/24 | ---------- | | ...
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68 views

php-fpm process in D state ,cause nfs wait rpc_wait_bit_killable

my wordpress site which is in clustered environment using NFS,nginx,php-fpm,mysql the infrastructure is hosted on amazon ec2.Under high load/traffic the php5-fpm process goes in D ...
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51 views

Is there any way by which I can capture the wifi probe requests without using monitor mode?

For some reason, keeping the wifi interface in monitor mode on my machine is crashing it(its a raspberry pi, I'm assuming its crashing because of the amount of traffic being intercepted, but lets not ...
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49 views

kvm linux guest no connectivity

I am running SolusVM using KVM, and network to Windows guests work fine. However, network to Linux (CentOS) guests do not work. Try to ping any IP, but get network unreachable. Obviously it can ...