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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/etc/resolv.conf to overwrite local bind

I have set up my /etc/bind to set up the following: dig @127.0.0.1 +noall +answer SRV _my-sub._tcp.example.com _my-sub._tcp.example.com. 300 IN SRV 0 0 12379 a0.example.com. _my-sub._tcp.example.com....
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1answer
192 views

ifup default route missing

One of our severs is behaving strangely with networking on startup. We've been using configuration changes and ifup/ifdown to try to isolate the issue, with frustratingly inconsistent results. We have ...
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26 views

OPENVPN ipp.txt file assigining duplicate ip addresses

I am having an issue with duplicate entries for hosts in the ipp.txt file where the same host CN has been added multiple times with different ip addresses. For some or other reason some of my openvpn ...
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1answer
196 views

How to start and stop a libreswan connection

I have a connection configured on my libreswan instance on two machines. The connection start automatically when I start the pluto daemon, I have try other settings, but the connection also starts if ...
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1answer
60 views

Can't ping public endpoints when IPSec tunnel is up

I'm using openswan to link two machines via IPSec. The tunnel comes online fine and I have connectivity to each endpoint via the VPN. However, when the tunnel is up, I lose connectivity to the ...
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1answer
43 views

kill tcp port binding by deleting proc/[0-9]/net/… in linux

I have a script to call syscall Kill the process that holds a certain TCP port in Linux (ubuntu). But even if I do that, sometimes the port still remains in /proc/[0-9]/net directory binding the port. ...
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42 views

Debian-Server: Incoming SSH/PING/TELNET/… works - outgoing does not

I've mentioned a strange behavior of my linux-system: After rebooting the system I can connect to it via SSH and the server responses to PING. But the server itself can not ping any other servers. # ...
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104 views

Dynamically enable IPSec for IP connections between many servers

For a given list of internet server (example): S001 - 45.67.89.12 S002 - 67.78.90.34 S... S999 - 98.76.65.54 I want to talk from each server to any other server to any TCP service using the public ...
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1answer
89 views

How do I set up squid reverse proxy to use https and http traffic?

I already have a squid reverse proxy working for two test sites. My two sites are www.test1.com and www.test2.com My current working config file looks like this /etc/squid3/squid.conf acl ...
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2answers
126 views

RHEL with two interfaces - Can't ping/ssh into second interface

I have a RHEL Server 'foo' with two interfaces: eth0: inet addr:172.16.15.75 Bcast:172.16.15.95 Mask:255.255.255.224 eth1: inet addr:172.16.15.242 Bcast:172.16.15.247 Mask:255.255.255.248 ...
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2answers
1k views

Apache 2.4 reload fails

My Apache won't reload after doing some changes, in this case after adding a new VHOST via Webmin. It's not the first time it happens, last time I resolved reinstalling Apache, indeed not a ...
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27 views

how change scope link on created interface

for example cat /proc/net/if_inet6 | grep fe80 fe8000000000000002e0edfffe21989d 0c 40 20 80 vlan3xxx fe8000000000000002e0edfffe21989d 09 40 20 80 vlan2xxx fe8000000000000002e0edfffe21989d 0a 40 20 80 ...
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0answers
112 views

What is the ip xfrm tmpl and how is it different than an SA?

The Linux ip xfrm policy command creates an IPsec policy, associating particular traffic with an SA. It uses something called a "template" (tmpl), which, as far as I can tell, is just a means of ...
2
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1answer
64 views

Linux route unexpected mtu

i'm observing rather strange (at least for me) behaviour for few routes in my network. i use gre interfaces on top of ipsec tunnels. these gre interfaces have mtu 1400 on my entire network. normally i ...
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1answer
201 views

How to change Interface Metric permanently in CentOS

My Config: Guest OS - CentOS7 Host OS - Windows 7 Interface - 3 (enp0s3, enp0s8, enp0s9) Installed in Virtual Box enp0s8 is Bridge to wlan0(For Internet) enp0s3 and enp0s9 are host-only Kernel IP ...
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0answers
44 views

Debian Host replies with ICMP Port Unreachable after Router Advertisement (ISATAP)

I'm trying to configure a Debian Wheezy host to get an IPv6 address via ISATAP (using isatapd). This machine has two outgoing interfaces: eth0 and eth0.20 (virtual interface using VLAN 20): 1: lo: &...
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78 views

Ubuntu 14.04 - TOR doesn't restore circuits after disabling due to traffic inactivity

I've HS server for web proxying purposes with an onion address. It's in a test phase atm and traffic is low, mostly generated by me when configuring and testing. From time to time web server is not ...
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2answers
113 views

can't connect to tomcat/telnet to a remote host

I want to connect to a tomcat installed on a VM which is running on my laptop however I am not able to connect to it. I stopped the IPTables to ensure that this is not a firewall issue. I can ping ...
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1answer
738 views

how to share apache /var/www using samba server in ubuntu

Have similar issue like this question virtual centOS 6.2 - How to share /var/www using Samba I get error "Windows cannot access \server1\dev" You do not have permission to access \server1\dev I ...
2
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2answers
36 views

Block specfic port for the access of the application from outside with impacting the access to local host scripts [duplicate]

I have setup one application 'phanthomjs' that is running of specific port 6423 I wish that it should be accessible to script that are run locally on the box 'localhost', not accessible from outside. ...
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25 views

Connection timeout after adding new IP on CentOS

After I added new IP according to guide from my provider: http://help.ovh.com/IpAlias i started having trouble with connection. While ping is always OK some ports don't work. I loose connection to ...
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2answers
829 views

Can't start CentOS 7 “network” service

I have a minimal CentOS 7.2 installation on a small mini PC with 6 ethernet ports. I chose to exclude NetworkManager from the install as I would prefer to use the basic network service or switch to ...
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0answers
14 views

How to provide connectivity to a bridge running in a different network namespace?

I have a bridge running in a different network namespace. I want to access this bridge in host system. For e.g: I have created a network namepsace: my_namespace. Now inside this network namepsace i ...
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57 views

Not able to ping ips created inside docker container using namespace in centos7

I have a docker container running inside centOS7. Now docker creates a bridge by default named as docker0 in host system. Inside the docker container, we have created another bridge named as eth2 ...
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2answers
54 views

How to send captured packets to a different destination?

I have some data packets captured using tcpdump in a pcap file. Now I want to send those packets to a another destination. how I can achieve this?
2
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1answer
47 views

How to mimic “DMZ Host” or “Default Host” NAT funcionality with iptables?

My previous DSL modem had a function called "DMZ Host" (which in other platforms seems to be named Default Host). When you select a computer in your network to be the DMZ Host, it forwards every non-...
3
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1answer
49 views

How to setup embedded Linux private vlan

I am trying to setup a vlan between 2 embedded Linux SOCs on wireless IPTV STB (set top box) using vconfig. The physical connection between the SOCs is a Marvell 88E60xx switch. The issue is that the ...
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0answers
27 views

Not able to block site on pfsense firewall with squid+squidgaurd

Currently running pfsense latest version and set the transparent proxy using squid with squidgaurd for filter but https is not enable because this feature not work well. So that I want to block sites ...
0
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1answer
571 views

RTNETLINK answers: File exists when using netem with tc

So I simply get this error when I enter this command in my master VM: sudo tc qdisc add dev eth0 root netem delay 97ms RTNETLINK answers: File exists Any idea how that could be fixed? I am ...
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1answer
27 views

Load-balance via netfilter

In iptables I can mark some packets(one of four, ie) in preroute and redirect after only marked packets. Is way to load-balance traffic via netfilter tables?
3
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1answer
89 views

Route Between Two Virtual Interfaces on one NIC Linux

I have an Ubuntu machine that is my firewall The Machine has 2 NIC Cards. eth0 and eth1. eth1 is connected to a modem that gives it an IP of 10.10.1.X eth1 is required to provide DHCP on 192.168.2.X ...
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1answer
98 views

Do I need to open any port for NTP synchronization to work if both outgoing and incoming are blocked on ufw?

One of my production servers, UFW configuration is as follows: Status: active Logging: on (low) Default: deny (incoming), **deny (outgoing)**, disabled (routed) New profiles: skip To ...
1
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0answers
124 views

tcpdump on bridge interface (virbr) does not receive any packets destined for one of its addresses

Here's the configuration for the interface: # ifconfig virbr0 virbr0: flags=4355 mtu 1500 inet 192.168.11.1 netmask 255.255.255.255 broadcast 255.255.255.255 ether 52:54:00:99:e3:...
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0answers
106 views

Error while trying to bring up network in SLES12.1

I am trying to bring up the eth0 adapter in SLES12 sp1 using ifup eth0 but every time I am getting an error saying: wicked: Reading config file /etc/wicked/client.xml wicked: Reading config file /...
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1answer
142 views

What are the implications of using a default DROP rule on a public DNS server

RHEL 6.6 authoritative DNS server. Right now in IPtables I have the INPUT chain defaulting to ACCEPT. :INPUT ACCEPT [0:0] I have been having some issues with it being attacked lately and I am just ...
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0answers
24 views

restart client after download .img file from PXE

I want to install pfsense using pxe. In Windows 7, I have installed the Tftpd32 software and set it up (conf file is below). The client machine downloads the image file (pfsense.img) successfully ...
3
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0answers
79 views

What would cause named to send out hundreds of bogus responses?

My DNS server running RHEL 6.6 is actively sending unsolicited DNS responses to a couple of IP's. By unsolicited I mean that there is no incoming request from the external IP, the DNS server seems to ...
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1answer
114 views

Hide my Linux machine from traceroute but still allow ping [closed]

i have a linux server running RedHat and i want to make it pingable but invisible to traceroute/tracert. i set some iptables rules but whatever i try is either block or allow both ping and traceroute. ...
0
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0answers
20 views

Guardian not found in smoothwall express 3.1

I have download latest version of smoothwall express 3.1 iso and install on virtual box but it's do not have Guardian web filtering. Is it need to install additionally ?
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0answers
31 views

Bandwidth throttling

i am trying to limit download speed on my server only downloads i tried to use wondershaper and trickle but they both mess up with my upload speed tried everything to fix it but no success so is ...
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0answers
34 views

ssh file tranfer freeze in file >100k

My ssh secure shell always freeze when I try to download file >100KB using SSH Secure File Transfer. Even if the download manage to start, the download speed is less than 1kb/s. But upload of large ...
0
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1answer
29 views

Am I able to change source and destination IP address on packet when output source depends on input destination IP?

I have a Linux server which is used to change the source and destination IP addresses. I was trying to set it up so it accepts packets with an destination IP of X.X.X.11 - X.X.X.15 and changes any of ...
0
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1answer
72 views

SSL certificate issue with git on pfsense

i have installed pfsense latest version and user are working on phpstorm and netbeans editors with git (https) and on gateway i have installed pfsense and configure transparent proxy using squid+...
2
votes
2answers
96 views

How to require all network activity to pass a KVM guest firewall before reaching the host?

Most of the information I've come across tends to set up a KVM firewall using a bridge connection. From my understanding it is a security risk if network traffic can reach the host without having to ...
2
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1answer
70 views

Setting up a secondary network interface (VPN) on a linux server using openvpn

Network WAN __|___ |Router| ‾‾|‾‾‾ ______ 192.168.0.1----(192.168.0.0/24)----192.168.0.102-|Server|-192.168.3.1---(192.168.3.0/24) ...
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1answer
35 views

Confused about virtual network interfaces needed for network

I am relatively new to networking and have researched a lot about the topic however I am still confused as to what kind of virtual set-up I need. I have linked a diagram of the network over here: ...
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0answers
16 views

Bandwith quota in private network

We have a private company network with Linux and Windows networks. All traffic to outside pass through a Debian firewall, managed by iptables. We need to set a bandwith quota for every device: we ...
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0answers
37 views

IPSec host2host transport-mode

I want to secure all traffic between our servers that are distrubuted through various datacenters. We don't have VLANs, just plain Debian 7 & Debian 8 based Virtual Private Servers (around 20), ...
3
votes
2answers
233 views

Apache webserver & Tomcat : Runing multiple tomcat webapps and apache webserver app at same time

We have a Debian X64 server which currently has a tomcat instance where we have 3 webapps in WAR file ofcourse. Also, we have an Apache webserver, which has one CMS system running. And one final ...
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1answer
45 views

Using dhcp and static ip on same nic on linux with systemd-networkd

I have a portabel device that sometimes needs connection to internet(to update) but will mostly be used directly connected to a laptop via ethernet cable. I want my users to have the plug and play ...