Tagged Questions

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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1answer
87 views

IPTables: Firewall with just one Eth device? [closed]

Admittedly I am a novice in the area of firewalls. But I have read on the IPtables and Firewall theory and command options. There is a general diagram by Rusty Russell, the creator of IPtables: ...
2
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2answers
590 views

ARP responds with single MAC address on Linux server with multiple interfaces on the same network

Linux server has 2 active network interfaces: IF:eth1 IP:192.168.1.1/24 MAC:11:11:11:11:11:11 (1GbE) IF:eth2 IP:192.168.1.2/24 MAC:22:22:22:22:22:22 (10GbE) The idea is that the ...
0
votes
1answer
57 views

Forward a host network traffic to another host with the exception of the ssh service

I am trying to redirect all the network traffic received in a old host to a different new host. For that i created two new rules on iptables of the old host: echo 1 > /proc/sys/net/ipv4/ip_forward ...
1
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0answers
208 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 ...
3
votes
1answer
248 views

How to ping ipv6 interface

I'm trying to get familiar with ipv6 I don't understand why I can't ping this interface at the inet6 addr eth1 Link encap:Ethernet HWaddr 08:00:27:77:9e:77 inet addr:192.168.33.10 ...
2
votes
1answer
251 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 ...
0
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0answers
96 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 ...
0
votes
1answer
85 views

How can I configure iptables to forward and forget?

I'm trying to create a front controller where users can connect to a specific port and have their connection redirected to a different IP/port. The reason I'd like to be able to do this is for ...
1
vote
2answers
369 views

Routing Internet traffic through computer on another subnet

Ubuntu box server has 2 network interfaces: eth0 50.57.71.100 eth1 10.182.161.100 Ubuntu box client has 1 network interface: eth0 10.177.30.100 server and client can already talk to each other ...
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0answers
33 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 ...
0
votes
1answer
147 views

Tunnel interface inside Virtualbox IP forwarding

I am working on a solution to expose a development stack that resides inside a Virtualbox guest up to the Internet through OpenVPN tunnels. OpenVPN client fires up inside the guest VM and connects ...
1
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2answers
53 views

Network Buffer Usage

I am facing some issues with my Application, and am curious to know the network buffer usage at any given moment. I am using a CentOS 6 linux Machine. I know the Default values are present in ...
0
votes
2answers
46 views

SCP version of - ssh -A -t -l root 192.16.4.9 ssh -A -t node-17

I'm on a vpn. I ssh to a machine through another machine like so ssh -A -t -l bob 192.16.4.9 ssh -A -t node-17 I now need to scp a file from node-17:/tmp/something. How can I do the above in one ...
0
votes
0answers
31 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 ...
1
vote
1answer
39 views

Sharing a file system, or how to horizontally scale access to files

My API mostly serves up stuff from the database, but a big part of the product is generating images by combining SVG files with large pattern fills (~50MB tiff files). The API can scale ...
0
votes
1answer
48 views

Unable to nmap open port. IPTables has it listed as open

I have an IPtables firewall set up on a single system. I'm trying to nmap it with the following command: sudo nmap -Pn -A (IP addr) I expect everything incoming to be filtered except for ports 22 ...
0
votes
1answer
42 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 ...
0
votes
2answers
44 views

Forwarding all connections to different address

I have a script that tries to connect to rabbitmq using default url and port (localhost:5672). Is it possible to make linux redirect all connections to this url and port to different server? I am ...
0
votes
0answers
49 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 ...
0
votes
0answers
146 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 ...
2
votes
1answer
58 views

Is the ethx mac address of a VM the same as the mac address of the corresponding tap interface?

I have a single node openstack install on an ubuntu machine. For some reason that I cannot figure out, the linuxbridge is dropping packets from this VM. My iptables seem to be fine (atleast as far as ...
0
votes
0answers
73 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 ...
0
votes
0answers
98 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 ...
0
votes
0answers
7 views

rhel4 user not working on different domain

I am using a red hat server 4. Installed oracle on it for network database Previously when i was looging as root in gui and opening terminal it was showing like this $root@localhost> but now it ...
3
votes
2answers
2k views

Is it possible for L2TP VPN to do auto route configuration for client during connected?

We've setup a L2TP VPN server with this tutorial, everything works like a charm. The only issue is We don't want client to route all traffic using this VPN, only a particular subnet, e.g. ...
7
votes
1answer
303 views

Is ISP's Equipment Misconfigured? Getting Martian Packets on Internet Interface

We have a /28 block from our ISP. Let's say 1.1.1.240/28 with a gateway of 1.1.1.241. We are getting martian packets from another customer over at 1.1.1.214. They are sending broadcasts to 1.1.1.255. ...
0
votes
1answer
65 views

rsync works one way but not the other

I have a problem with using rsync. When I try to copy a remote file I get the following error: [home ~]$ rsync test.txt qnx: sh: rsync: cannot execute - No such file or directory rsync: connection ...
0
votes
0answers
134 views

QNAP LDAP server cannot change primary user group

We are setting up a new QNAP server in our office. We have set up NFS and LDAP to share users and files in a linux only network. The LDAP is giving us some trouble. As the default user group Domain ...
-1
votes
1answer
42 views

How to choose source IP from multiple virtual IP's based on specific destination

I am having two private IP attached to an interface. inet 10.255.0.127/24 brd 10.255.0.255 scope global eth1 inet 10.255.0.153/24 brd 10.255.0.255 scope global secondary eth1 When traffic leaves ...
0
votes
2answers
104 views

How do I set Securityonion/snort to not capture certain packets?

After looking through my pcaps from Security onion I'd like to filter out a host (let's call it 192.168.4.4) and filter out some traffic (ports 80 & 443), current project is to look at other ...
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votes
2answers
182 views

Iptables MASQUERADE: What is the advantage/disadvantage between these two commands? [closed]

What is the advantage/disadvantage between below 2 commands: iptables -t nat -A POSTROUTING -o eth0 -s 10.0.0.0/16 -j MASQUERADE AND iptables -t nat -A POSTROUTING -j MASQUERADE Some Background ...
1
vote
2answers
2k views

AWS VPC + IPtables + NAT: Port Forwarding is not working

Yesterday, I posted a question here but I think was not clear enough in my words. BTW, This question is not a duplicate. I have AWS VPC Setup as below. GOAL/PROBLEM: SSH to Server A from internet. ...
0
votes
2answers
108 views

Android/Linux Ping sends another packet before packet timeout

I have to send 10 packet & timeout for each packet should be 3 secs. As Android pings works on Linux ping commands, I am using below ping command in my application: ping -c 10 -W 3 -s 32 ...
0
votes
2answers
180 views

IPtables: Forward port to another host is not working

I am trying out something so this is my test setup: Setup: I have AWS VPC with a public and private subnet. I have a host in public subnet with a public IP address (say Host A) I have a host in ...
3
votes
2answers
406 views

Results of MTR on STDOUT?

I am trying out mtr (My traceroute) for educational purposes. However it is quite disturbing that I can't manage it to print results to stdout directly. Per default it opens a GTK-Window where it ...
1
vote
2answers
115 views

Red hat reporting more NICs than are physically present

We just deployed several servers (hp dl360p g8), and after the initial boot we're noticing that none of the network devices are showing up as cabled. Ethtool shows no link anywhere. Even more weird is ...
0
votes
2answers
87 views

Occasional Delay on Website Resources: Packet Loss Due to Bandwidth Cap?

My website loads more slowly than I think it should, due to a few of the assets taking an absurdly long time to download from the server. I've been trying to track down the cause of this. I'm about ...
0
votes
0answers
90 views

Tomcat fails to return syn requests to F5

I have an F5 LTM sitting in front of two tomcat servers which host 4 applications. When I initially create the pools and add the members to the LTM I can hit all applications. This is the weird part, ...
1
vote
1answer
59 views

connect two vpn server

I have 2 VPS in 2 locations. The first vps is located in Iran and has the ip : A.A.A.A. The second vps is located in the USA and has the ip : B.B.B.B. I run pptp/l2tp on server 1 and my VPN users ...
0
votes
1answer
513 views

Virtual network interfaces starting on boot even though they are set to onboot=no , what could be the reason?

I've re-installed my main database server with CentOS 6.5 . I've configured the relevant NIC's including 3 virtual interfaces, called em2:0, em2:1 and em4:0. For some unknown reason the NetworkManager ...
1
vote
0answers
101 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 ...
0
votes
2answers
309 views

Point to Point Connection Between Two Hosts

I am trying to set up a point to point connection between two Linux host machines. I've connected both of them with crossover cable, but they can't ping each other. Here are the configurations for ...
0
votes
1answer
308 views

Linux Cannot change tx-checksumming

On a Linux 3.2 kernel: Linux 3.2.0-4-686-pae #1 SMP Debian 3.2.46-1+deb7u1 i686 GNU/Linux on VmWare, i get checksum errors on ipv6 tcp packets. So I can ping6, but not connect by ipv6 to ssh, smtp, ...
0
votes
1answer
97 views

Make a bridge with two ports behave like a veth pair

I have a linux bridge with two ports, namely p0 and p1, and I would like to modify the bridge behavior so that every frame showing up in one port is relayed to the other port and viceversa, i.e. the ...
0
votes
2answers
90 views

Wan emulation on linux

I have to connect two different geographic networks with an OpenVPN (for instance) Before doing that "in the real world", I wish I could test my configuration. My main idea is the emulation of ...
0
votes
1answer
123 views

new centos os servers, nfs mounting is really slow

So i am setting up two new boxes (actually linodes) nfs.server - CentOS release 6.2 in my /etc/export i have /home/unit 192.168.131.103(sync,insecure,no_subtree_check,no_root_squash,rw) ...
0
votes
0answers
54 views

Preventing SSH to use VPN

I use a VPN service on my Debian server which I connect to remotely using SSH. The problem I'm facing is that when I connect to the VPN on the server I get disconnected from SSH since the server's IP ...
-2
votes
1answer
70 views

networking - Dedicated NIC for different traffic

I have two servers which acts as a reverse proxy which accept incoming requests from internet and passes on to application servers, then responses from the application servers are then served to the ...
0
votes
0answers
115 views

Is it possible to send 127.0.0.1 traffic to eth0, while keeping this IP in the loopback interface? (Linux)

The question is pretty straightforward as in the title, but almost everybody who I asks this to tries to convince me I'm crazy or stupid. I'll explain here why I need this, and I welcome other ...
2
votes
2answers
90 views

IPtables NAT puzzler: Why is traffic from the firewall host being NATed even though it's not coming from one of the prescribed source addresses?

I run a small network where a linux web/mail server also provides NAT for a collection of windows boxes. One of these windows machines is apparently misbehaving (ZeroAccess botnet even though I can't ...