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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Kali SYN Flood (Metasploit), not denying service

I have a server with apache2 installed. I tried to do a dos attack on the server by using kali linux syn flood attack, but i am still able to access the website on the server. msf auxiliary(synflood) ...
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2answers
187 views

Is it possible to do Linux network namespaces (netns) on MacOS?

Context - I'm trying to get a docker cluster running on MacOSX. Part of the install process for getting docker running is to install pipework. Pipework relies on /var/run/netns My question is: Is ...
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2answers
190 views

All traffic is passed through OpenVPN although not requested

I have a bash script on a Ubuntu box which searches for the fastest openvpn server, connects, and binds one program to the tun0 interface. Unfortunately, all traffic is being passed through the VPN. ...
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2answers
266 views

Force an LXC container to use its own IP address

Sorry if this question has already been asked. I could not find it, I have this setup : +---------------------------------------------------------------------------------------------+ |HOST ...
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0answers
25 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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1answer
220 views

How to stabilish a VPN connection, only on port 8080

Infrastructure: Here's what I want, be able to connect to the website 10.10.100.32:8080 from my LAN on 'Router 1', and all the traffic outside the port 8080 should go to the default gateway 'Router ...
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176 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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1answer
62 views

Trace route to specific page on a website [closed]

If I can access a site (ie: serverfault.com) through my proxy/firewall, it means that it will allow all it's subdirectories (serverfault.com//)? I can access the website site.com/ but it returns me ...
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1answer
101 views

Rate limiting udp packets destined to a linux machine

Is there any way to ratelimit udp packets destined to my linux machine? I am sensing some udp packet drops destined to my machine. Was there any default udp rate limiting conf in linux? I have seen ...
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1answer
30 views

How to set up custom multicast address

What would it take to setup a custom made multicast ip address in the network? Machines are linux. Let's say I want to have a multicast address with only some machines from the network as group ...
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2answers
414 views

Linux adds the wrong default route

For some reason my Centos 5.9 Linux 2.6.18 x86_64 wants me to have two default routes. Whenever I reboot the server, my routing table looks like this: [root@server1 ~]# route -n Kernel IP routing ...
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1answer
72 views

Network configuration for linux server

I had some troubles with a Linux server after being restarted. I can log to the machine but I cannot remotely access this machine via ssh client: ssh -v -v -v root@IP gives me connect to host IP port ...
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1answer
142 views

Can't reach multi-homed Ubuntu from different subnet

I have a multi-homed Ubuntu 12.04 server. I have two network interfaces connected to two different IP ranges. 2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen ...
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3answers
1k views

How can I achieve OpenVPN client routing without NAT on Linode

I've set up an OpenVPN network, and it is working properly in the sense that I can access the inner/LAN machines from the remote client. However, my problem is that all traffic from the remote ...
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2answers
2k views

What is the correct way to open a range of ports in iptables

I have come across articles advising for the following: iptables -A INPUT -p tcp 1000:2000 -j ACCEPT And others stating that the above will not work and iptables only supports multiple port ...
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0answers
228 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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1answer
95 views

Ban an IP when the server received an amount of data from it

What I need : There are many result for adding a drop rules by an amount of request per laps of time, but I need to drop by received byte count from a particular address over a period of time. ...
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3answers
271 views

In Linux, how can I automatically assign an IPv6 address to an interface based upon its IPv4 address at boot time?

On a CentOS 6 machine, I have a server with 2 NICs, eth0 and eth1. eth0 has address 192.168.0.1. I would like to create a script that parses the IP address of eth0 and assigns a similar-looking IPv6 ...
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1answer
166 views

Split tunneling through two VPNs simeltaneously

I want to run two OpenVPN client instances on an Ubuntu Server 14.04. I have both .conf files that can work independently (both are set to different interfaces - tun0 and tun1). I want to run both at ...
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1answer
120 views

How to exclude LAN traffic from IPSEC policy

I am trying to replace a Firewall/VPN appliance (Snapgear SG300) with another (Mikrotik RB951G-2HnD). My current router works, but, for the new mikrotik router, when I add the phase 2 tunnel, I can ...
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1answer
46 views

specific machines on subnet randomly lose connectivity, but the rest of the network is fine

Every physical machine is connected to a cisco switch and is on the same network 192.168.1.0/24 Every server I have is running Centos 6.5. A couple run KVM with a bunch of virtual machines. Most of ...
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3answers
138 views

Linux (Ubuntu 12.04) sending ARP requests over single interface

I have a system with custom hardware hooked up to 2 different ethernet ports on the same system. The interfaces are configured on the same subnet because the hardware (FPGA-based) has a hardcoded IP ...
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44 views

Policy routing UDP traffic

this should be a quick one. I have not found any documentation addressing this topic. I have set up some policy routing on my raspberry, but it seems like UDP traffic is completely ignored. Some rules ...
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0answers
174 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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4answers
287 views

One second delay before tcpdump returns packets

Using Ubuntu, I'm trying to sync tcpdump sniffing with self-identifying "pings" from a client device. The problem is that getting precise starts and stops is made difficult by what looks like a ...
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34 views

Redirection of nfstraffic to different host ip

I am setting up an environment with NFS. I have a setting where a SVR1 has two interfaces. I receive NFS-requests on one interface(192.168.122.2). I need to redirect these nfs request via the other ...
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1answer
449 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
50 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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1answer
494 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:ad64::/64 dev lo like described here on my Debian server, but I seem to be missing something. If I ping ...
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0answers
81 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
67 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. ...
2
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1answer
71 views

iptables: does a scanner knows if you DROP packets?

I know how REJECT and DROP chain works. But, as I read here REJECT vs DROP when using iptables, user Dagelf said that the server still replies with TCP SYN/ACK. Does the scanner knows that a packet ...
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0answers
25 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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0answers
123 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
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1answer
412 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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2answers
240 views

what does `pipe <number>` mean in `ping` output?

While running a test to diagnose some alleged network problem, I got this output from ping: --- r01c01b11n02 ping statistics --- 30000 packets transmitted, 29995 received, 0% packet loss, time 6309ms ...
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1answer
58 views

Software for emulating networks and NAT

I am working on a software that I need to test with different types of NAT, and I would like to set up a test environment I can reconfigure in different NAT modes. I would like to have: ...
2
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1answer
160 views

Assign different Hostname to different NIC

I have four network card on my server, I have assigned each with an specific IP now I want to set an different hostname for all the interface? What is the difference between setting the hostname in ...
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1answer
171 views

Is it possible to configure Apache to not listen on port 80 when connecting from localhost

Is it possible to configure Apache to not listen on port 80 when connecting from localhost, but allow the connection on port 80 from an external IP?
2
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1answer
203 views

Netstat hangs: why?

Sometimes (not too often at all) when I type "netstat", it takes over 5 seconds to return. While other times is instantaneous. I have been observing this for weeks on my server (CentOS 6.4), but I ...
2
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1answer
169 views

Host doesn't send ACK-SYN packets for transparent proxy

I am setting up a transparent proxy using haproxy, the setup works without the 'source 0.0.0.0 usesrc client' line. When I add that line in, the endpoint is called from the original client's ip ...
0
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1answer
262 views

Can't connect to 2 different Linux computers via VNC (local network)

I have a problem connecting to Vino VNC server with 2 Linux Computers running Xubuntu. The computers are Based on the ODroid U3 chip which is ARM based. When both of the ODroids are on the same ...
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3answers
442 views

How to find out capacity for network interfaces?

I could get the capacity for the network interface by lshw, but which file in sysfs is this information stored(i.e. which file in /sys/class/net/eth0/device/ directory)? $ sudo lshw -class network ...
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3answers
61 views

Is it possible to route network traffic according to user ID?

On my Debian system, I'd like one of my users to use a different network interface as their default route for all internet traffic. I know how to use iptables to block the other interfaces, but not ...
0
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1answer
285 views

disable a network interface on booting ubuntu

I use ubuntu 12.04. I need to boot with one of the network interfaces 'eth1' down. I tried adding sudo ifconfig eth1 down to /etc/rc.local However it seems the interface is brought up and ...
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1answer
99 views

Linux 25 port routing (tunneling/forwarding)

I have: 1) Centos server 1 with postfic/dovecot mail servers IP1 45.45.45.45 (DNS: host1.com.ua) server 1 cannot make outgoing request to 25 port because Internet Service Provider block it! ...
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1answer
53 views

How do I close ports in Linux for security reasons (KVM)? [closed]

I am going to set up a KVM virtualization server on CentOS. The host machine and several of the VMs will have a dedicated IP addresses. I'm going to need to close off unused ports and probably ...
2
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0answers
1k 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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0answers
94 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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41 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 ...