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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42 views

route table issue when I appended option net.ifnames=0 to grub2

I appended two options net.ifnames=0 biosdevname=0 to grub2 because I want to change default network name to old name eth0 on RHEL 7. After that, I edited /etc/sysconfig/network to set default ...
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0answers
85 views

Debug slow lan (ssh, nfs) file transfer

I've got two linux boxes attached to a gigabit switch. They both have gigabit NICs, cables are cat7. Testing the network with iperf shows a fast connection but transferring files with rsync, scp, or ...
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2answers
61 views

IPTABLES: Route outgoing http requests to eth1

I am trying to route all outgoing HTTP requests LEAVING my server to go through a proxy (tinyproxy) on another server. I want the transmission to the proxy to use our LAN which is on eth1. No matter ...
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0answers
108 views

How to diagnose netstat: no namelist

I had to replace an NIC on my HP Proliant Microserver, running FreeNAS 9.3 In my crashplan jail, I now get "netstat: no namelist" as a response when I execute the netstat command. How to I diagnose ...
0
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1answer
46 views

Why does my network work with an incorrect broadcast ip?

I have a block of public ips. The network is /28 starting at .80 By that rational, the broadcast ip should be set to .95, however the broadcast ip set in /etc/network/interfaces for every server is ...
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34 views

Debian preseed: DHCP ok , PXE-TFTP KO

to automate install of debain by preseed file, I builded a debian Jessie with tftp-hpa and pxe package installed on. The DHCP is managed by my windows server. All workstation get correct IP address ...
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0answers
27 views

Use of PTPd on RedHat/CentOS

I need to create a reliable and accurate synchronization between two CentOS 6 machines connected through a direct Ethernet connection. I've seen that on Linux several implementation of the IEEE 1588 ...
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0answers
25 views

Iptables Port redirection don't take effect

Im tying to setup a mitm proxy to sniff my Android smartphone. I found this helpful tutorial. At the point where I need to teach Ubuntu to redirect everything from port 8080 to 443 and 80 I'm running ...
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204 views

Strange iperf3 behaviour with UDP streams

I am using iperf3 verson 3.0.11 to measure the throughput of a UDP stream between two virtual machines. The virtual machines are deployed via OpenStack. Of the physical hosts, one is located in ...
2
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1answer
40 views

Basic forwarding on Ubuntu not working

I have the following setup, minimized to explain the problem: _________ |Desktop | ...
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0answers
427 views

DNS_PROBE_FINISHED_NXDOMAIN when trying to acess page from a local server

I'm working in a company where we use a local server in linux to store some data, particularly our BugZilla, Wiki and a subversion repository. The server is accessed both locally from the development ...
4
votes
1answer
103 views

How to dynamically find the name and type of interfaces attached to a system

I have a use case where I need to dynamically configure some files which includes the name of the interfaces present in system say eth0 , wlan0 . However when I change the system sometimes its changed ...
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2answers
41 views

/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. ...
0
votes
1answer
164 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 ...
0
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0answers
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 ...
0
votes
1answer
155 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 ...
0
votes
1answer
54 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 ...
0
votes
1answer
40 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. ...
2
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0answers
39 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. # ...
2
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0answers
103 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 ...
1
vote
1answer
81 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 ...
1
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2answers
101 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 ...
2
votes
2answers
743 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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0answers
23 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
76 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
votes
1answer
60 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 ...
0
votes
1answer
154 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
40 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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0answers
62 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 ...
0
votes
2answers
99 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 ...
0
votes
1answer
605 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
votes
2answers
35 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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0answers
21 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 ...
0
votes
2answers
705 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 ...
0
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0answers
12 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 ...
0
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0answers
54 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
48 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
votes
1answer
42 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 ...
3
votes
1answer
46 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 ...
0
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0answers
24 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
votes
1answer
432 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 ...
0
votes
1answer
26 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
votes
1answer
78 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 ...
5
votes
1answer
86 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 ...
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0answers
119 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 ...
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0answers
90 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 ...
0
votes
1answer
105 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
votes
0answers
74 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 ...
-2
votes
1answer
101 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. ...