Internet Protocol version 6 (IPv6) is the latest version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet.

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OpenVZ OpenVPN IPV6 Routing Problem

I have an OpenVZ server with OpenVPN on it, and I also have IPV6 being routed to it. (Currently two /64 blocks) I was trying to route one /64 block to the main system for use with other processes such ...
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2answers
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Adding recursive entries into `/etc/hosts`

I'd like to add shorthands for various FQDNs into the /etc/hosts file, such as: pyrrha.compsci.university.org. pyrrha Is there a way to force the local DNS resolver to process the /etc/hosts ...
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5answers
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Curl with ipv6 not working by default

I am trying to curl ipv6 addresses, but without success. If I try lets say: curl https://google.com I wait for a timeout and get network unreachable If I force ipv4, everything is fine. ...
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enp3s0: link is not ready

I've some strange messages in the dmesg output: [ 7.588762] IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready [ 7.589616] IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready [ 7.591897] ...
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1answer
161 views

Blocking SSH Brute Force attacks on IPv6

I recently had to work with some servers that have an IPv6 connection and I was surprised to find out that fail2ban does not have IPv6 support, neither does denyhosts. Searching on google I found that ...
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9answers
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Convince apt-get *not* to use IPv6 method

The ISP I work at is setting up an internal IPv6 network in preparation for eventually connecting to the IPv6 internet. As a result, several of the servers in this network now try to connect to ...
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3answers
422 views

How to use shell to derive an IPv6 address from a MAC address?

We know that we can use the MAC address to create an interface identifier, e.g. for a link-local IPv6 address which should be unique in the Network. The image shows the way to do this: My ...
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2answers
3k views

What is the purpose of avahi on a RHEL 7 server?

Running a server machine with CentOS 7, I've noticed that the avahi service is running by default. I am kind of wondering what the purpose of it is. One thing it seems to do (in my environment) is ...
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1answer
45 views

Why is my CentOS 6 system doing IPv6 lookups?

I have a fairly recently installed CentOS 6.6 system. I have disabled IPv6 as best I can: IPV6INIT=no in ifcfg-[eth0|lo] net.ipv6.conf.all.disable_ipv6 = 1 in /etc/sysctl.conf ...
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1answer
50 views

Centos 7 with facebook php-sdk4 - Network is unreachable

I am not sure why I am getting this error. Sometimes, it works and sometimes I get this error in the error log: Exception: Failed to connect to 1a02:1234:f000:4:face:b00c:0:1: Network is unreachable ...
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0answers
48 views

Linux Routing Question

I was wondering how it would be possible to have multiple IPv6 default gateways on CentOS linux. I currently have two interfaces with IPv6 (venet0 and tb0), both with different blocks routed to them. ...
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1answer
52 views

To stop auto generated IPv6 link local address

How can I stop assigning of link local IPv6 address? I have tried to do it by disabling the accept_ra and autoconf options, but it is not working.
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1answer
58 views

Assigning link, site and global IPv6 address

How can I assign link, site and global IPv6 addresses at a same time using /etc/network/interfaces file? I am able to assign any one of them address at a time.
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0answers
90 views

Having problems when connecting pppoe in my Kali Linux

Here is my log: Jun 6 04:57:23 unknown pppd[3333]: pppd 2.4.5 started by root, uid 0 Jun 6 04:57:36 unknown dbus[2534]: [system] Failed to activate service 'org.freedesktop.Avahi': timed out Jun 6 ...
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0answers
202 views

Force IPv4 over IPv6 only for certain addresses

I'm currently running Debian 8 and I'm trying to force applications like Google Chrome to use IPv4 over IPv6 only for certain sites. My ISP natively offers IPv6 and it's amazing on all websites that ...
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3answers
70 views

How does the iptables work with IPv6?

I would like to set up a firewall on Linux Debian for IPv6. It is important to use iptables for me. I have tried to change the ipv4 folder to ipv6. How can I set up iptables for IPv6?
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1answer
189 views

Why is my DAD slow?

The last few boots of my Arch Linux, I noticed I had no network access. I'm using a netctl profile to give my adapter a static IPv4 address, which by itself works fine. So I had a look at the logs, ...
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3answers
3k views

Why does SSH show protocol as tcp6 *and* tcp in netstat?

$ netstat -nat Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:80 ...
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150 views

dhcp ipv6 dynamic prefix delegation

I'm trying to setup Linux-based home gateway with IPv6 support. IPv4 configuration is finished and I'm using IPv4 NAT, ISC DHCP for addresses allocation, PowerDNS for local DNS setup, PDNS recursor to ...
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1answer
64 views

How does Debian select or prioritize IPv4 and IPv6 connections?

I'm going to explain my question with an example. I have two servers, A and B, both runs Debian 7.8, both have dual-stack connection to the Internet (I don't know if it matters but they even have the ...
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1answer
53 views

check tcp packets reception below tcpdump level

I am having an issue with my smartphone device and packets monitoring: I am trying to find a reason why I cannot establish a VPN connection via PPTP protocol. I have the following successful ...
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1answer
59 views

ipsec.conf file with dynamic ipv6 address

I have been able to get strongswan ipsec tunnel between 2 linux machines with static ipv6 address. For example, a segment of my ipsec.conf file looks like left=2000::1 ...
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2answers
111 views

How can I add an IPv6 gateway?

For example: ip -6 route show | grep ^default There is no output. So there's no default gateway for IPv6. also I see some complains from the kernel side of things: dmesg | grep IPv6 eth0: no ...
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1answer
631 views

Reverse DNS with BIND and IPv6

So I'm trying to set up reverse DNS for an IPv6 address using BIND9, and I'm having a little trouble getting it to work. Assume I have 2001:41D0:2:D447::/64 assigned to my server and I want ...
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1answer
126 views

IPv4 goes offline several times per hour on headless remote server, IPv6 unaffected

On my Ubuntu 14.04.2 server IPv4 goes offline several times per hour (one to four times I've seen, but at no particular minute per hour or so). My hoster insists that the problem is on the ...
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1answer
2k views

How can I disable IPv6 in custom built embedded setup

I have an embedded system built using buildroot. I have had a number of network issues, one of which is that my machine cannot see its gateway despite it being on the same subnet. I have tried using ...
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0answers
72 views

How does s_client turn ip6-localhost into 127.0.0.1?

When I use openssl s_client and ask it to connect to ip6-localhost it actually connects to 127.0.0.1 instead of ::1. This is what I see on both Ubuntu and Debian: $ strace -e connect openssl ...
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1answer
189 views

Permanently disable IPv6, for a given interface?

I'm looking to permanently disable IPv6 on a specific interface because it's broken and my question on Superuser to fix it is dead so how can I go about doing that? I've added ...
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2answers
617 views

How to configure dhcpd to register ipv4 with bind while having static ipv6 addresses?

I have IPv6 configured on my local network via radvd; it advertises a routable IPv6 block, that all the machines auto-configure.s I have IPv4 assigned to a NAT'd block via dhcpd and that updates ...
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0answers
177 views

FreeBSD: IPv6 in Jails (ezjail)

I'm on FreeBSD 10.1 and in the process of setting up a server. After some hassle I managed to get IPv6 running. I'm now setting up jails with ezjail and I learned how to set up a working flavor and a ...
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1answer
275 views

Not able to resolve IP address for eth1 in Vagrant VM

On runnning ifconfig command I get the following as output. I need the IP address of eth1 for running my python server port with. eth0 Link encap:Ethernet HWaddr 08:00:27:CE:08:3D ...
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Ipv6 Network unreachable Debian

Been trying to configure ipv6 on my proxmox server for about an hour now and I just can't seem to get it right. /etc/network/interfaces: auto lo iface lo inet loopback auto vmbr0 iface vmbr0 inet ...
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3answers
328 views

OpenVPN using IPv6 on VPS

I'm trying to create an IPv6 tunnel using OpenVPN on Debian Sid. IPv4 is working fine, but I can't get IPv6 to work. I can ping the server and other clients using IPv6, but I can't reach the internet ...
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1answer
297 views

ip6tables allow IPv6 traffic from OpenVPN through my VPS

I've established a fully working IPv4 OpenVPN setup and wanted to go one step further and experiment with setting up IPv6. My VPS server does not get a native IPv6 block but does have a 6in4 tunnel ...
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1answer
292 views

Link Local IPv6 address keeps being automatically assigned

I'm looking to prevent the IPv6 link local address from being randomly assigned. I'm not looking to disable v6 but rather statically assign my own link local. I've done ifconfig vboxnet0 inet6 add ...
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1answer
92 views

How can I resolve MAC knowing ipv6 addr w/o ip command?

I installed OpenWrt on my router and I wanted to get MAC address of some machine connected to it. With ipv4 I would use arp command. But I want to resolve HW address knowing ipv6 addr. I have read ...
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99 views

Flow of ipv4 over ipv6 tunnel

Re-posting my question from stackoverflow I am trying to achieve flow of ipv4 packets over ipv6 tunnel between 2 machines. Initially i had the following setup Linux1 eth0 ...
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0answers
134 views

How can I have hosts register their IPv6 addresses in Windows DNS

Windows clients support registering their IPv4 and IPv6 addresses in DNS after obtaining the address from a DHCP server or via IPv6 Router Advertisements. For my CentOS 7 and Fedora 21 boxes I'd like ...
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How do I make OpenVPN split /56 IPv6 block into /64 subnets for each client?

I want OpenVPN to occupy, for example, 2001:0DB8:5912:1200::/56, assigning /64 subnets of it to clients (so they can serve as SLAAC routers if needed). What should I do? Is OpenVPN alone enough for ...
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2answers
446 views

IPv6 connections timeout

I'm having issues with IPv6 connections. Only with those. They timeout roughly every 10 minutes (due to address renewal i suppose). Happens with every debian based flavour of linux i tried in a year ...
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2answers
205 views

IPv6 Zone ID in /etc/hosts

I'd like to setup a static hostname for an IPv6 address on local network. It seems, however, that /etc/hosts won't accept a zone ID - when I append a zone ID to an IPv6 address, it acts as if the host ...
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0answers
189 views

Why does /proc/net/if_inet6 not contain all IP addresses from 'ip addr'?

Since recently, after moving from Ubuntu 10.04 to 14.04 (kernel 2.6.x to 3.13), I noticed a strange thing about IPv6 addresses. I assign several IPv6 addresses to my eth0 interface to allow the Apache ...
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0answers
90 views

cacti snmp ipv6 snmp error

I configured cacti on centos6.4, only ipv6, when snmpwalk command to check a client, the output is normal, but add monitoring host (ipv6) on cacti, appear "snmp error" error, how can I do? Here is the ...
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1answer
116 views

Get static ipv6 ip

I'm trying to get an IPv6 IP for my wireless interface. When getting an IPv4 I see this: wlan0 Link encap:Ethernet HWaddr 00:15:00:bf:29:b2 inet addr:192.168.1.128 ...
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3answers
3k views

DHCPv6 prefix delegation server for linux?

What linux DHCPv6 client can I set up so it requests a prefix on one interface and then on all the other interfaces it will give out addresses (or if requested, a smaller prefix delegation)? It would ...
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1answer
4k views

How to add ipv6 default route

I have the following setup Linux 1 Linux 0 eth1 eth0-------------------eth0 14.14.14.80 19.19.19.20 19.19.19.10 2005::5/64 ...
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1answer
95 views

Why is ping6 using IPv4 socket?

I enabled IPv6 in a CentOS 7 server and everything is working as expected, except for ping6: it is showing 3-5 delays between requests (but the RTT is fine): $ ping6 www.google.com <...5 ...
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1answer
160 views

Manually configure ipv6 address in 2 different subnets

I have a following setup Linux1---------------Linux2------------------Linux3 (eth0) (eth1) (eth0) (eth0) I have this in a local network i.e the Ethernet cables are ...
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1answer
91 views

Why does my tunneled IPv6 connectivity drop after a short period of time?

I correctly setup a Hurricane Electric tunnel on a CentOS 6.5 VPS server (KVM). I use CSF (ConfigServer Security & Firewall) which acts as a wrapper for iptables and ip6tables, the default ...
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0answers
128 views

TCPDump To Capture A Tracepath6 Datagram

I'm trying to use TCPDump to capture an IPv6 datagram using: tcpdump -c 1 -i eth1 -vvvs0 ip6 and dst host H2.net2 & tracepath6 H2.net2 I'm running this script on H1.net1; R12.net1 is the ...