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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Method to hijack or otherwise exploit ssh [on hold]

I plan on using plink to connect external Windows computers to application on network I'm administering, by employing port forwarding through ubuntu server. Since recently there have been various ...
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2answers
35 views

Clear TCP sessions

I am trying to use iptables to reject packets as well as reset the TCP connection. My rule is: iptables -I FORWARD -p tcp -s 10.0.0.10 -j REJECT --reject-with tcp-reset If 10.0.0.10 is SSH'ing into ...
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16 views

Linux router showing packet loss

I have two linux boxes that are using a third box as a router. Packets flow normally. BoxA(10.0.0.10) -> (10.0.0.20) RouterBox (172.16.50.20) -> BoxB(172.16.50.30) When I run mtr from BoxA to BoxB the ...
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1answer
27 views

forwarding ping using ip route [on hold]

I have a Linux setup which consists of two interface. A local LAN interface and virtual interface. ETH0: 150.10.15.194 PAN0: 192.168.255.209 I would like to set rules that route all ICMP echo ...
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0answers
15 views

reducing bufferbloat in linux web server

I'm looking for all the buffers I can tune in linux as well as their order of operation. On the server, nearly all operations are run over the TCP protocol. I want to eliminate bufferbloat to improve ...
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2answers
37 views

SSH Connection through a Reverse (Remote) SSH Tunnel

This is the setup I have : a Linux box A inside a LAN behind a firewall. a Linux server with a fixed IP address that is accessible from the internet. I want to be able to connect to the Linux box ...
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0answers
7 views

bird4 - OSPF not learning/distributing /32 routes in hub-and-spoke topology

in my hub-and-spoke setup all the boxes are happily exchanging local LANs routes through bird4/OSPF. The links between the hub and the spokes are VPN p2p links and I need the address of every spoke's ...
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0answers
12 views

Changing value of tcp_fin_timeout in unix machine

I was looking at this article in which they have mentioned how to increase two property for better performance of application if we see lot of TIMED_WAIT connections My question is: if I modify ...
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1answer
37 views

“net.c:577: sendmsg() failed: Operation not permitted” in dig Output

I am running Bind 9.10.2 version on CentOS 6.6 machine. While running the dig command, i am getting "net.c:577: sendmsg() failed: Operation not permitted" notification. dig utility is giving me an ...
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2answers
112 views

Stop China from connecting to my Google Compute Engine server

My company has a Google Compute Engine server hosted in North America. We get so many Chinese IP addresses sending requests to port 11 that it is costing us money for the ingress. Our firewall blocks ...
6
votes
1answer
112 views

Is it possible to process millions of datagrams per second with Windows, using a vendor agnostic API?

I am investigating if I can implement an HPC app in Windows that receives small UDP multicast datagrams (mostly 100-400 Bytes) at a high rate, using a dozen or up to maybe 200 multicast groups (i.e. ...
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1answer
22 views

Routing issue on Linux with Mobile Broadband

Note: This is a "cross-post", I asked this same question on "superuser" StackExchange site, but without obtain any answers, just a comment (now curiously disappeared). I've thought this site is ...
6
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0answers
32 views

SynProxy can not return syn ack packets with asymmetric dual bridge topology

I have a asymmetric dual bridge topology as shown below when i connect from 172.16.11.5 and 172.16.10.6 with ssh but i can not connect because of SynProxy. ------- ...
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0answers
15 views

Iptables drop forwarded traffic destined for interface IP address

I have a small VPN setup where I use IP tables to nat traffic coming in the vpn0 interface to the IP address of the eth0 interface. These rules look like this: iptables -t nat -A POSTROUTING -o eth0 ...
0
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1answer
13 views

How do i keep ISC-DHCPD from offering different IPs when there is two requests from the same MAC

I have a set of Nodes which get their addresses from ISC-DHCPD. Since they boot using PXE, there will be two rounds of DHCP (one from the PXE, one from the OS) and for some reason, ISC-DHCPD will ...
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0answers
17 views

Need all local traffic through Debian - Routing? [migrated]

Been dealing with this for some hours now and my head are really spinning. So I got this cable network router (192.168.0.1) that Im trying to pass all my local traffic to. But I cannot for the life ...
2
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0answers
38 views

Mounting encrypted Samba share (linux server/client)

I'm trying to set up encrypted samba access. In order to achieve that I've added 2 lines to [global] scope in smb.conf: server signing = mandatory smb encrypt = mandatory But unfortunately I can't ...
0
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1answer
63 views

Starting to learn about IPtables, why do I need this rule?

I have been reading all day about IP tables, how the rules work, sets of rules for basic webservers, etc. Now I`m trying to configure my webserver with IPtables using this thread as a starting point: ...
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0answers
33 views

Linux traffic control input interface using more than output interface

this thing is driving me crazy for days now simple nat router using `iptables masquerade and simple linux tc using htb here are the commands iptables -t nat -A POSTROUTING -o eth0 -s 10.1.1.2 -j ...
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2answers
59 views

Can iptables automatically drop established session after certain seconds?

Can iptables drop automatically an established output session after certain seconds e.g. 30 sec. since its launch? But I want to restrict it only for destination port 80 and 443. The purpose is to ...
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2answers
27 views

Creating Virtual Proxy Server

I know this is not this kind of forum, but I can't find anything in google that really answers my question. Is there possible to create a Proxy server running in a Virtual Machine using only 1 ...
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1answer
47 views

docker0 bridge status toggles between enabled/disabled, what could be causing that?

I have some CoreOS bare metal instances that are displaying unusual behaviour on the docker0 bridge device. On one of the instances where this has been occurring, I'm running couchbase server and it ...
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votes
1answer
24 views

port forward in INPUT level

I want to change the destination port of the ipv6 packet in the INPUT level. So I tried to use ip6tables with nat in the INPUT level but seems this command does not work # ip6tables -t nat -I INPUT ...
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0answers
16 views

home network bridge + access point [migrated]

I want to create a wired bridge to a wifi setup a firewall + intrusion detection and then setup a wifi-access point for lan-out I currently have a d-link 1200 extender setup as bridge, my desktop ...
0
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1answer
30 views

AutoFS mount multiple CIFS Shares to same directory

As long as I had only one mount everything was fine. file: /etc/auto.master /mnt /etc/auto.srv1_share1 file: /etc/auto.srv1_share1 sh1 -fstype=cifs,rw,user=jdoe,domain=srv1,noexec,password=xxx ...
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0answers
29 views

What's the best way to create a captive portal access point if my authentication is on a website?

I have my access point set up with dnsmasq and hostapd. Hostapd supports authentication but it is local authentication. I need the user to be limited to a specific login URL, where once they hit the ...
0
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1answer
44 views

dual-homed Centos 7 cannot be ping'd or ssh'd from some on LAN, sees ssh connection refused on one subnet

I have 2 subnets, A and B and a router connected to both A and B and the WAN. I have 4 servers dual homed on subnets A and B, 2 of them are Mac OS and 2 of them are Centos 7 (1503). They are all ...
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0answers
48 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
2answers
62 views

Port 22 is accepting connections, but not visible in netstat, unhide etc

So I have this weird issue where one of my boxes is accepting connection on the ssh port (22) even after sshd is stopped. I tried to identify the listening process by the typical means sudo netstat ...
0
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1answer
15 views

Upgrading Web Application's Systems' Kernels for IW10 & other related improvements - upgrade all machines? LB first? Most important?

Stackers - We're making the push to upgrade the systems for our web app to take advantage of the various TCP improvements becoming more readily available (e.g. ...
0
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1answer
26 views

Running OpenVPN on Xen node causes guest VM to view all inbound connections as originating from the node IP

I have two node servers running Xen 4.2 -- I'll call them Node A and Node B. Node A is running OpenVPN as the server. Node B is running OpenVPN as the client. Both nodes host a number of Xen guest ...
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4answers
766 views

Transfer large amount of small files

I've to do a migration of two servers with large SAN attachments to our new VMWare environment. EDIT: I have to supply some additional intelligence as I have good answers regarding VMWare solution. ...
0
votes
1answer
81 views

Route traffic through private IP for only certain hosts - CentOS 6.6

I am having a weird problem which I cant figure out - so I was hoping someone here could give me a hand. First off the end goal is that a specific server in my network runs an IPSEC connection to ...
1
vote
1answer
198 views

Update version of network manager

In shell on sever I see following error after launching several commands: Error: nmcli (1.0.0) and NetworkManager (0.9.9.1) versions don't match. Force execution using --nocheck, but the results are ...
0
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1answer
25 views

Allowing all ports from an IP

I have successfully entered the following command to iptables sudo iptables -I INPUT -p tcp --dport 5000:5020 -j ACCEPT -m comment --comment "Allow Ports 5000s" However, AFAIK this allows access to ...
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0answers
22 views

How to automatically remount iscsi drive, after network errors on Vmware + FreeNAS

Is it possible to force Ubuntu to remount, rescan storage in time manner, to automatically mount it in rw mode? I have a Ubuntu virtual machine on VMware server. And have physical FreeNAS server ...
0
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0answers
44 views

KVM port-forwarding from ppp0 to VM's bridged NIC not working, but to VM's NAT NIC works?

I've spent a lot of time on this freaky problem, I've created a simple host and VM configuration to try isolate the problem. Terminology in this question Host: The bare metal server VM: The KVM ...
0
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0answers
35 views

How to setup 2 switch with VLAN and 2 IPs for each in different block

Below I have depicted the required network. In this network: Lets say GW1 is in IP1 block and GW2 is in IP2 block. There are 2 Linux running PCs with 4 NICs. 1st Linux PC is connected to 2 GWs with ...
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0answers
27 views

How can i configure a static ipv6-prefix to one linux host [duplicate]

I have a virtual Linux server (Kubuntu 14.04) and i will ask the hosting provider for a complete /64-Prefix for this machine (at the moment i have 4 individual IPv6-Addresses). How do i configure the ...
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votes
1answer
31 views

Cater to multiple countries? [closed]

I run a game server off a linux machine with a single IP address masked by a proxy. The box is located in an LA datacenter, and for players in some other countries, they experience a high ping ...
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votes
1answer
34 views

Why must the IP be configured on the bridge device? [closed]

My understanding of a network bridge is having a kind of "virtual switch" which virtually connects the network devices (that were added to the bridge) as if I would connect them to a real switch with ...
-1
votes
1answer
64 views

Debian - Routing multiple virtual interfaces

I've a Debian computer with multiple external IPs (7 in total), each IP has its own virtual interface (eth0:1,eth0:2, etc...) I would like to know: how can I configure routing so each time I ssh to a ...
3
votes
3answers
168 views

Iptables rules with ! character

I have entered iptables rules to log a specific connection on our server, but it doesn't seem to be working as I want it to. Here are the rules: 1 LOG tcp -- !10.51.0.0/16 ...
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0answers
26 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 ...
0
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2answers
36 views

arp table entry outside configured network

Can someone tell me why do I have arp table entry outside interface network? Server has 2 interfaces, both on the same network: eth0 10.10.34.146/22 eth1 10.10.33.188/22 ip route default via ...
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2answers
53 views

Http Requests: how to identify a machine using multiple IP addresses

I have an http server. Is it possible to identify a machine, which is making http requests to my http server using different IP addresses? In other words, is it possible to identify a machine, by ...
-1
votes
1answer
59 views

Cannot Access remote CentOS machine using VNC

I am trying to connect to a remote CentOs machine through VNC to get a graphical display. I have followed the steps mentioned in https://www.howtoforge.com/vnc-server-installation-centos-6.5 to ...
0
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2answers
93 views

Linux Red-hat 6 Network manger interface priority

I have a question regarding RedHat 6 Enterprise Network Manager (NM): My Linux is connected to two network interfaces. 1 – eth0: Normal Ethernet which is connected to the company LAN 2 – eth1: An ...
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0answers
23 views

Ubuntu DHCP-RELAY Error

I have a Ubuntu 14.04 server running as a router (4 NICs with IP forwarding turned on). The routing/forwarding component is working fine. However, I now wish to implement a DHCP-Relay/IP helper so I ...
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0answers
20 views

iptables, after specifying an interface to drop traffic it drops all traffic of all interfaces

We have currently the situation that one interface (eth0) is linked to the internet. and we 2 other devices (eth1/eth2) for management purposes. Now the idea is to block off eth0 completely from the ...