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.

learn more… | top users | synonyms

2
votes
0answers
55 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 ...
2
votes
0answers
50 views

Linux - Outgoing connections from process timeout after the process restarts

banging my head against the wall with this one... I have an Ubuntu Linux server, on top of which our own process which holds 40K persistent connections to external services. When the process ...
2
votes
0answers
36 views

What are the advantages NAPI before the IRQ Coalesce?

As known there are two approach to avoid some overheads of hardware interrupts in highload networks, when there are too many hardware interrupts, that switching to them takes too much time. It is very ...
2
votes
0answers
147 views

How to route traffic through different interfaces based on the port number?

iptables -A PREROUTING -i usb0 -t mangle -p tcp --dport 8080 -j MARK --set-mark 1 iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain ...
2
votes
0answers
44 views

IPsec - strange behavior

I have set up site-to-site ipsec connection between linux(debian) and mikrotik router. The tunnel is up linux configuration: config setup interfaces=%defaultroute keep_alive=60 ...
2
votes
0answers
38 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 ...
2
votes
0answers
113 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 ...
2
votes
0answers
487 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 ...
1
vote
0answers
44 views

IP-rules don't seem to be working on CentOS-6.6

I faced a bit odd difficulty with policy-based routing on CentOS-6.6 server. I have a setup where I need to enroute all packets originated from 172.25.0.0/16 destinated to 172.24.0.0/16 and some ...
1
vote
0answers
25 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 ...
1
vote
0answers
28 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 ...
1
vote
0answers
43 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 ...
1
vote
0answers
22 views

Process-wide VPN connection via openconnect

I'm using openconnect to connect to a remote endpoint and SSH onto the machine inside the remote network. The problem is, when I do create the connection, the machine I do it on is unresponsive for ...
1
vote
0answers
228 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 ...
1
vote
0answers
31 views

dhcp relay with failover to local service

I'd like to set up a dhcp server which normally relays to a central site, but has a pool of addresses to hand out if the link to the central site goes down. I'm using isc dhcp server on Debian, but ...
1
vote
0answers
76 views

How to use iptables or IFB to mark incoming traffic by device?

I'm trying to use iptables to mark incoming packets based on the device where those packets arrived (rather than their originating IP address or port etc), but haven't found a way of getting this to ...
1
vote
0answers
71 views

Routing with multiple NICs on debian

I have a machine with two NICs on different network segments, I've set up routing for the different segments. It works if I run all the routing commands manually, but I can't get it to work when ...
1
vote
0answers
27 views

How to check a given connection has been offloaded to network card

From what I read, some part of the tcp protocol operation can be offloaded from kernel to network card driver thanks to TOE (or GSO, LSO, LRO..). My objective is too find if a given socket has some ...
1
vote
0answers
47 views

Rsync does not delete destination files [rsync protocol / module]

An automatic backup script executes the following rsync command to sync a local directory tree with a remote one: env RSYNC_PASSWORD=$rsync_password rsync -aqrxz --delete --timeout=30 \ ...
1
vote
0answers
132 views

How to create openvpn tunnel between multiple interfaces between two hosts ubuntu linux

I want to create OpenVPN tunnel between two Ubuntu 12.10 hosts which has two interfaces, say: Host1: eth0, eth1 Host2: eth0, eth1 A tunnel is wanted between: Host1 (eth0) <-> Host 2 (eth0) ...
1
vote
0answers
91 views

linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
1
vote
0answers
134 views

Route traffic for a specific IP through a specific interface

I'm setting up a server that tunnels all its traffic over an OpenVPN connection. The VPN connection is further tunnelled over obfsproxy hosted on the same machine. The problem is that as soon as the ...
1
vote
0answers
52 views

Configuring openldap/PHP LDAP against “signed” LDAP connections with Active Directory

This may sound like a stupid question, and maybe it's already been answered, but I can't find a definitive answer anywhere, so I thought I'd ask. When someone enables "Domain controller: LDAP server ...
1
vote
0answers
108 views

Separate L2TP/IPsec VPNs with dynamic VLAN assignment

I am working on a Linux (Debian 7) VPN concentrator for different kinds of remote access. One of the offered protocols is L2TP/IPsec because of the client availability. I am using xl2tpd which in turn ...
1
vote
0answers
66 views

Redirect Default Gateway Traffic in Linux to File

I am trying to troubleshoot one of my linux servers (ubuntu server). Therefore I want to intercept all traffic that is sent to the default gateway and then write it to a file: preferably some kind of ...
1
vote
0answers
111 views

Enabled Intel® I/O Acceleration but no bytes transffered

I enabled IOAT but it seems that no data is transferred using DMA for network: I enabled IOAT in bios. CPU is Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz. I loaded the module in ubuntu 14.04 ...
1
vote
0answers
110 views

Load Balancing over multiple ISP connections

I have been trying to implement load balance and fail over on a linux machine having multiple interfaces. Currently I am using two ISP lines and I wish to split the network traffic such that both of ...
1
vote
0answers
80 views

Printer on OS X not printing across VPN subnets

I have an interesting situation where I have a two servers that connect two subnets via a VPN. One side is 192.168.0.0/24 and the other is 192.168.1.0/24. Communications appear to be working okay. I ...
1
vote
0answers
177 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 ...
1
vote
0answers
76 views

Policy routing local user's traffic down a tunnel

I've got a Linux based Firewall/Router running iptables and SNAT for traffic passing through it to the Internet via a single uplink - This is working fine. There is also a small number of applications ...
1
vote
0answers
36 views

Chef - handle resources changing the network interface

I'm using chef to deploy an openvpn application in bridging mode to an ubuntu node. In my recipe i'm using a bash resource to create the bridge necessary for the vpn to work. Unfortunately the bridge ...
1
vote
0answers
32 views

IPSEC on linux with multiple remote ISP

I have configured 2 ipsec VPN connection from my linux server to my clients locations. the reason being the client has two ISPs a primary and a secondary on. The client wants to switch to secondary ...
1
vote
0answers
28 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 ...
1
vote
0answers
273 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 ...
1
vote
0answers
383 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 ...
1
vote
0answers
110 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. ...
1
vote
0answers
198 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 ...
1
vote
0answers
925 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 ...
1
vote
0answers
317 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 \ ...
1
vote
0answers
282 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 ...
1
vote
0answers
52 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 ...
1
vote
0answers
120 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 ...
1
vote
0answers
426 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 ...
1
vote
0answers
128 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 ...
1
vote
0answers
54 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 ...
1
vote
0answers
105 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 ...
1
vote
0answers
195 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 ...
1
vote
0answers
328 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 ...
1
vote
0answers
158 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 ...
1
vote
0answers
164 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 ...