Questions tagged [linux-networking]

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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Testing -How to generate limited rate tcp streams?

Running with ubuntu. I have clients that has limited transfer rate. I need to test my server to see in how much clinets with limited transfer rate it support? Is there any utility that allow me to ...
Avihai Marchiano's user avatar
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1 answer
2k views

How to define iptables rule to add all transport to a given interface to nfqueue

Running on Ubuntu. I have machine 1 < - > machine 2 < - > machine 3. I dont know machine 1 or machine 3 ip. It can be any ip. machine 1 send packet to machine 3 and machine 3 send packet to ...
Avihai Marchiano's user avatar
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1 answer
2k views

Ubuntu Server 12.04 ISC-DHCP-Server not working using standard configuration

I have been trying to configure the isc-dhcp-server package to assign ip addresses to devices connected to my eth1 adapter. Current Configuration interfaces: auto lo iface lo inet loopback auto ...
Alex Hope O'Connor's user avatar
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2 answers
3k views

Iptables port forward tftpd

i need to forward incoming port 69 to port 2112 with iptables on linux. i don't need any NAT etc. just accept incoming connections to port 2112 like it be 69 pot. Thank you!
Raspizdyay's user avatar
1 vote
1 answer
5k views

Setting iptables rule for all protocols for specific source and destination ports

Is it possible to add a IPTABLES rule which allows all the protocols for specific source and destination ports? I tried the following but it didn't work. iptables -I FORWARD 1 -s 172.27.0.254/255.255....
Ravi's user avatar
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1 answer
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RHEL BIND Server Intermittent error

I have a RHEL 5.7 server running bind-9.3.6-16.P1.el5. At seemingly random points during the day, the DNS will fail to resolve hosts on the LAN for about ten seconds. WAN hosts always resolve. Then ...
Chris E.'s user avatar
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1 answer
1k views

Validate send packet against recived packets?

Running Ubuntu. I have machine A -> machine B (one-way connection from A to B) . Machine A goal is to forward tcp packets to machine B (it dosnt has tcp connection with machine B. it just forward tcp ...
Avihai Marchiano's user avatar
1 vote
1 answer
579 views

Service httpd restart error

Why do i always get the error when ever i reset my httpd: Starting httpd: (98)Address already in use: make_sock: could not bind to address [::]:80 (98)Address already in use: make_sock: could not ...
user131274's user avatar
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1 answer
183 views

Cant access LocalHost from Browser

I hav installed apache2 & php 5.3x on centos 6.3 by using following commands: yum install httpd yum install php Now I'm trying to access php page from my local machine browser using following ur:...
user131274's user avatar
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IP setting in CentoOS 6.2x64 by XenCenter 6.2

I have setup a Guest CentOS virtual machine in Xenserver.. I have updated the Xentools but i cannot find the option to config my IP Address which is showing to be 'unknown' currently. All i need to do ...
user131274's user avatar
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gather information about packet from malicious ip

I have a glassfish server running some webservice and I noticed that there is an abnormal traffic from japan (150.70.x.x) in my iptables log file and I dont have any user in this country . Until now ...
isoman's user avatar
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Analyzing a periodic network spike

One of my servers has a semi-predictable network input spike at 6:45 every day. It comes as early as 6:30 and as late as 6:50, but always lasts for less than 1 minute. I'm trying to figure out how to ...
Mikhail's user avatar
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1 answer
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Routing via Linux

I have an individual network with a single machine having IP Address 10.10.10.4. Another machine (Gateway Machine) has two NICs: eth0 and eth1. eth1 (10.10.10.10) is connected to the internal network ...
Abdullah's user avatar
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1 vote
2 answers
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linux sever interfaces automation

I am using a CentOS server which has about 6 active interfaces with different IPs, I'd want to automatically bring down all the interfaces when any one of the 6 interfaces is down. Is there a way this ...
Ralf's user avatar
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3 votes
1 answer
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Why rinetd is working locally but not working remotly?

/etc/rinetd.conf 0.0.0.0 443 10.30.224.7 636 allow * >lsop -i|grep rinetd rinetd 27099 root 4u IPv4 2553556 TCP *:https (LISTEN) Also iptables -L -n returns nothings. Still, ...
sorin's user avatar
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Is it possible to boost my server's LAN bandwidth with two Ethernet ports?

Is it possible to boost my server's LAN bandwidth with two Ethernet ports? I have two Ethernet ports on my Dell PowerEdge SC1435 and I routed both eth0 and eth1 to my router, but for some reason I'm ...
Zack Zatkin-Gold's user avatar
9 votes
2 answers
33k views

Higher rmem_max value leading to more packet loss

The rmem_max Linux setting defines the size of the buffer that receives UDP packets. When traffic becomes too busy, packet loss starts occurring. I made a graph showing how packet loss increases ...
Nicolas Raoul's user avatar
6 votes
2 answers
6k views

Cheap way to detect client round trip times for http

I am trying to figure out a way to detect round trip times for each IP that connects to port 80 on my server. What is a good way to do this? There are far to many connections, and pinging each ip is ...
sajal's user avatar
  • 602
2 votes
1 answer
2k views

Limiting a process' network access on Linux?

I've been researching how to sandbox processes, and I came across cgroups, which looked promising. I'm not super interested in using virtualization or strace for this, since I want programs to run as ...
HFLW's user avatar
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1 answer
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IBM HS23 Blade Server (7875) onboard NIC driver for linux

I work with IBM HS23 Blade Server (7875). It's onboard NIC adapter is: Emulex OCl11104-F-X Virtual Fabric Adapter 2-port 10GB and 2-port 1GB LOM . I'm tryed to the following Linux OS with the ...
Igor Spivak's user avatar
2 votes
1 answer
12k views

Determine the IP address of the DHCP server from a client machine

I would like to know what is the best way to get the DHCP server address from a client (linux based), who just got an IP address from the DHCP server? I searched and found this in most of the ...
SSaikia_JtheRocker's user avatar
8 votes
1 answer
12k views

Iptables / What is the difference between connmark and mark?

While adding iptables rules, I couldn't understand what is the difference between connmark and mark? If anyone explains it with detailed explanations, I will be appreciated.
ibrahim's user avatar
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3 votes
3 answers
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How to route UDP traffic from one public IP (linux) to another public IP(Windows)

I want to prevent direct access of my Windows Machine and want to expose some programs running on it via my Linux Machine (which again is accessible by a Public IP). Is there a way where-in I can ...
Mahendra Liya's user avatar
1 vote
1 answer
4k views

Static Network configuration with bridge in CentOS 6.2

I have a server with CentOS 6.2 installed, I want to use it as a VM host to run some windows installations for development purposes. I wanted to be able to directly RDP and serve websites from IIS on ...
Kyle's user avatar
  • 183
4 votes
2 answers
3k 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 ...
HOLOGRAPHICpizza's user avatar
-1 votes
3 answers
9k views

tcp handshake failed.client send rst (after syn-ack). can any one advice?

topology: 2 linux computer connected directly . no iptables rules (except - iptables -A OUTPUT -p tcp -j NFQUEUE ) no firewall. route is defined as - "route add default dev eth0" on the second one ...
Avihai Marchiano's user avatar
0 votes
1 answer
788 views

server dosnt produce syn-ack

I have a small program that take packets from the nfqueue . change the ip.dst to my server dst (and ttl), recalc checksum and return the packet to the nfqueue. The server and the client are linux and ...
steve's user avatar
  • 9
1 vote
2 answers
2k views

Hosting websites on a public ip routed via a private subnet using one Linux machine as both router and server

I use Ubuntu server as router, NATing router and webserver. The server is connected to ISP with a public /29 subnet. Also I host some important websites on it. I asked the ISP to provide ipv6 address ...
nixnotwin's user avatar
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0 votes
1 answer
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Two network interface bridges - one LAN

I have little bit lack of linux networking understanding, so there is my question: We have 2 computers (SRV1, SRV2). Each of it has 1 NIC and both are connected by OpenVPN bridge Configuration: ...
Anton's user avatar
  • 115
3 votes
1 answer
2k views

Configure IPv6 routing

I've got IPv6 addresses from SIXXS. My host is connected with SIXXS network over a AICCU tunnel ("sixxs" interface). My host address is 2001:::2, the host on the end has address 2001:::1. On my host ...
godlark's user avatar
  • 33
3 votes
2 answers
3k 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....
Neil's user avatar
  • 131
0 votes
1 answer
1k views

TCP handshake ok, then the client isn't receiving any packets from the server

Topology: Client ----- Intermediate Device ----- Server Client: win7 Intermediate Device: unknown Server: CentOS 5.8 The problem occurs when the client and server are trying to establish a SSL ...
xiaofeng.li's user avatar
0 votes
1 answer
510 views

Xen dom0 crashed

Lots of questions this week, I got this error on dom0, then the server crashed (according to /var/log/messages): Jun 22 10:02:09 453 dhcpd: DHCPACK to xx.xxx.xxx.xx (xx:xx:xx:xx:xx:xx) via eth0 Jun ...
JohnT's user avatar
  • 49
1 vote
1 answer
1k views

Which Linux distro can join Windows 2008 R2 ADS domain

Any opinions on which distros are best to use for connecting to a Windows 2008 R2 domain. I started off by evaluating various different strains of Linux with a view to establishing which were best ...
NickC's user avatar
  • 2,513
1 vote
2 answers
2k views

Linux (Ubuntu 12.04) two gateways one nic

I have Ubuntu 12.04 Server edition Two gateways, both on 192.168.0. network, let's make them 192.168.0.1 and 192.168.0.2 I've read you should be able to add second gateway into /etc/network/...
David's user avatar
  • 11
8 votes
1 answer
8k views

Listing the routing table takes long time to complete

When I print routes defined on my computer using route, it takes about 5 to 20 seconds to complete. Why does it take so much time? With VPN enabled: $ time sudo route Kernel IP routing table (...) ...
Rafał Rawicki's user avatar
1 vote
1 answer
2k views

Rewrite URL based off of IP on OpenWRT

We are running OpenWRT on a WRT54GL. I have been looking for an answer to this, but I can't seem to figure out what to search for, if its possible, or what combination of programs to use. I want to ...
Scott's user avatar
  • 11
6 votes
2 answers
36k views

debian set eth0 autoneg off speed 1000 duplex full: Invalid argument

I use debian for my things,but when i config speed 1000 and duplex full the error occur the exactly command i use: ethtool -s eth0 autoneg off speed 1000 duplex full Cannot set new settings: ...
altman's user avatar
  • 125
1 vote
4 answers
1k views

Route web browsing through a separate iterface

I'd like to route web browsing through the wlan0 interface and the rest through eth1. Can you please help me with the iptables commands to achieve this. Below is my configuration. Thank you :) Edit: ...
tkane's user avatar
  • 141
-4 votes
1 answer
3k views

What are some options for acquiring a free realtime Linux distribution? [closed]

By realtime I mean something that can help with fast network I/O; Low-latency and high-throughput.
JohnPristine's user avatar
-2 votes
2 answers
119 views

Can I use squid (or anything) to do this? [closed]

I have a really crappy VPS, and a really good computer at my office (with a really good internet connection), but behind a NAT. Is it possible to expose my good computer by doing this: The good ...
user269334's user avatar
1 vote
1 answer
141 views

network user isolation

My question is for a network with a Linux iptables router gateway. How can it be possible to prevent inter-network traffic of those users. Think this case as a public network, IPs are distributed ...
seaquest's user avatar
  • 698
1 vote
2 answers
6k 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) ...
mhay's user avatar
  • 49
5 votes
1 answer
1k views

qemu with tun virtual networking issues

I'm trying to setup a virtual networking environment using open-wrt qemu and vde2 The script to boot two qemu instances and conenct them together is the following IMAGE=/home/northpole/openwrt/trunk/...
ndp's user avatar
  • 205
2 votes
1 answer
7k views

Port appears open locally but closed from another machine

I am currently trying to set up a Hadoop distributed compute cluster on my network. Currently. my cluster nodes are encountering a problem communicating with my master server. Right now I am working ...
ILikeFood's user avatar
  • 399
1 vote
3 answers
15k views

NAT via iptables and virtual interface

I'm trying to implement the following scenario: One VM-host, multiple guest VMs, each one gets its own IP-address (and domain). Our server has only one physical interface, so the intended use is to ...
Alex's user avatar
  • 538
1 vote
1 answer
4k views

Load balancing ISPs on Ubuntu Server

I have a Dell server with Ubuntu 11.10 Server installed on it. The server has 3 Ethernet cards eth0, eth1 and eth2. I have two ISPs say ISP1, ISP2 eth0 has a public IP (provided by ISP1 - we require ...
chochim's user avatar
  • 145
5 votes
6 answers
30k views

Ubuntu Server 12.04 can access LAN but not internet

Using Ubuntu Server (12.04) via command line, I can access the LAN (e.g. ping local machines) but not the internet (e.g. "ping google.com" or "sudo apt-get update"). How should I troubleshoot this? I'...
Paul Masri-Stone's user avatar
2 votes
1 answer
4k views

Eth0 Interface Not Coming Up on Fedora 14

I'm trying to upgrade some old Fedora 13 servers to Fedora 14 following Fedora's docs. The yum commands ran very quickly and seemingly without error. However, when I rebooted after finishing the ...
Cerin's user avatar
  • 3,650
1 vote
1 answer
1k views

Linux rename vlan tagged interface - routes stick around from the old one

We use a 10Gig NIC with two vlans on it (private network and internet facing), and I am changing the routing on our private network via renaming the network-scripts for it. This is on CentOS 6.0. ...
Brian L's user avatar
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