Questions tagged [ipv6]

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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240
votes
9answers
169k views

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 ...
37
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2answers
10k views

What is the difference between “all”, “default” and “eth*” in /proc/sys/net/ipv[46]/conf/?

In sysctl, the /proc/sys/net/ipv[46]/conf/ keys have the following subkeys: all, default, and a key for each network interface. For example, on a machine with a single network interface eth0, it will ...
23
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2answers
37k views

netstat — why are IPv4 daemons listening to ports listed only in -A inet6?

I have a computer with: Linux superhost 3.2.0-4-amd64 #1 SMP Debian 3.2.60-1+deb7u3 x86_64 GNU/Linux It runs Apache on port 80 on all interfaces, and it does not show up in netstat -planA inet, ...
19
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2answers
42k 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 ...
18
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2answers
72k 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 ...
14
votes
2answers
53k views

“IPv6 support is disabled” warnings

I get the error while running a script which tries to send emails. send-mail: warning: inet_protocols: IPv6 support is disabled: Address family not supported by protocol send-mail: warning: ...
14
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2answers
1k views

Meanings of ip address notation [::]:[someport]

what does this ip address notation means [::]:[4443].
13
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2answers
12k views

How do I get the pingable IPv6 address of my machine?

when I try: $ ip -6 addr I get something like: inet6 fe80::d773:9cf0:b0fd:572d/64 scope link if I try to ping that from the machine itself: $ ping6 fe80::d773:9cf0:b0fd:572d/64 unknown host $ ...
13
votes
1answer
16k views

Routing public ipv6 traffic through openvpn tunnel

What I'm trying to do is to route IPv6 traffic through a vpn tunnel. That way, I should be able to use IPv6 in a network that doesn't support IPv6. I have a VPS which has an IPv6 block assigned. Part ...
11
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5answers
3k 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 questions ...
11
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3answers
30k views

Is it better to set rules in ip6tables or disable ipv6?

I have the following network configuration: # ifconfig -a eth0 Link encap:Ethernet HWaddr 00:e0:1c:73:02:09 inet addr:10.1.4.41 Bcast:10.1.255.255 Mask:255.255.0.0 inet6 ...
11
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2answers
2k views

Is there a browser that supports IPv6 Link Local addresses?

I'd like to know at last one browser that allows me to browse fe80::4216:7eff:fe9f:79ac%enp2s0f0, for example. I've checked there're many tickets open in bug trackers of big name browsers like Firefox ...
10
votes
4answers
3k views

IPv6 addressing, dynamic prefix static local part

The router on my network hands out an IPv6 prefix assigned by my ISP. This prefix is dynamic but "fairly sticky". I would like my machines to automatically pick up the prefix advertised in the RAs, ...
10
votes
2answers
17k views

How to check if IPv6 is enabled on a Debian Linux?

Can one disable the IPv6 stack on Debian Linux, especially Wheezy? If so how do I know if it's disabled on a system?
10
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2answers
2k 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 ...
9
votes
2answers
83k views

Static IPv4 & IPv6 configuration on CentOS 6.2

I try to configure static IPv4 & IPv6 configuration on CentOS 6.2. The configuration below works perfectly : # ifconfig eth0 x.x.x.x/29 # route add defalt gw x.x.x.y # ip addr add dev eth0 XXXX:...
9
votes
2answers
6k views

How to disable requesting AAAA records when I have no IPv6 address?

Why can I see AAAA DNS requests when I run tcpdump on my Scientific Linux PC when I haven't got any IPv6 addresses? I already rebooted after setting NETWORKING_IPV6=no in /etc/sysconfig/network and ...
9
votes
1answer
1k views

curl request to IPv6 localhost gets stuck

A docker container of mine exposes a HTTP interface on port 8500, which is mapped to host port 8500. It is not IPv6 enabled. This still means, I should be able to access it at localhost:8500. IPv6 ...
8
votes
1answer
3k views

What is the IPv6 equivalent for 127.0.0.0/8

I am trying to set up an IP6tables firewall on Linux and I basically want to start copying my IPv4 configuration. One of my rules simply accepts all traffic to the localhost subnet: iptables -A ...
8
votes
3answers
9k views

Resolving hostname takes 5 seconds

I've a master bind9 DNS server and 2 slave servers running on IPv4 (Debian Jessie), using /etc/bind/named.conf: listen-on-v6 { none; }; When I try to connect from different server(s) each connection ...
8
votes
3answers
20k 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 0.0.0.0:...
8
votes
2answers
2k views

Linux assigns an fe80::/64 address to an interface. Shouldn't that be fe80::/10?

Per the IPv6 standard, Linux assigns IPv6 link local addresses to interfaces. These interfaces are always assigned /64 addresses. Is this correct? I would think they should be /10. Why are they ...
8
votes
4answers
15k 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 ...
8
votes
3answers
11k views

How can I disable automatic IPv6 neighbor route advertisement on a router?

I work for an ISP that's in the process of making its infrastructure IPv6-ready. Our core routers already have a working setup, but a large portion of our fiber customers are behind a router running ...
7
votes
3answers
7k views

How can I view IPv6 router advertisements that are being received by my computer for diagnostic purposes?

How can I view IPv6 router advertisements that are being received by my computer for diagnostic purposes? Are there any tools "built-in" to the majority of distros?
7
votes
1answer
7k views

wget uses ipv6 address and takes too long to complete

On a server wget-1.16 takes 8 minutes to complete: $ wget http://http.debian.net/debian/dists/stable/Release -O - --2017-06-12 23:44:40-- http://http.debian.net/debian/dists/stable/Release [...
7
votes
1answer
13k views

Netcat (nc6) - Minimal IPv6 only TCP Server and Client

I am trying to set up a basic IPv6 only echo-server using netcat (or rather nc6). Client and server are both in the same local network. However, the client quits immediately: IPv6-Server: $ nc6 -6 -...
6
votes
2answers
4k views

Why does dig -6 google.com not work for me? [closed]

Result of dig -6 google.com: ; <<>> DiG 9.8.3-P1 <<>> -6 google.com ;; global options: +cmd ;; connection timed out; no servers could be reached What does it means if dig -4 ...
6
votes
2answers
3k views

Route and “e” flag

k# route -6 Destination Next Hop Flag Met Ref Use If ::/0 fe80::8001 UGDAe 1024 0 0 eth0 [...] What does flag "e" mean?
6
votes
2answers
376 views

The first email bounces; the second and subsequent emails go through

550 relay not permitted That's the error message when email sent by Exim4 from my Debian laptop bounces. What's weird is that only the first email bounces. Second and subsequent emails pass through ...
6
votes
1answer
5k views

avoid IPv6 link local address on interface

I have a setup with virtual Xen hosts connected to a set of VLAN-s. On Dom0, I have set up a bridge for each of my VLAN-s to connect DomU-s to. Bridges are set up in /etc/network/interfaces like ...
6
votes
1answer
4k 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 ...
6
votes
3answers
7k views

How to disable IPv6 on OpenBSD?

I'm sure that in my network I will not use IPv6 only IPv4. So according to the KISS principle I will need to disable it. How can I do it? OS is OpenBSD 5.1.
6
votes
3answers
25k views

SSH login via IPv6 successfull while using IPv4 to the same host yields “Permission denied”

I'm currently stumped by a strange problem… I have a dual stack host to which I want to SSH. If I connect via IPv6 everything works like expected datenwolf@foo ~/ > ssh -6 bar.example.com Password:...
5
votes
2answers
7k views

What's the use for the special ipv6 addresses in /etc/hosts?

I have the following block in my /etc/hosts: # The following lines are desirable for IPv6 capable hosts ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::...
5
votes
2answers
2k 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 ...
5
votes
1answer
16k views

How to get Pi-Hole to work with IPv6?

At home I have installed Pi-Hole on a Fedora 28 machine, and it is now working properly serving IPv4 addresses via DHCP, acting as the DNS server, and blocking IPv4 addresses as appropriate. However, ...
5
votes
1answer
6k 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 net.ipv6.conf.eth0....
5
votes
6answers
19k views

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. curl ...
5
votes
3answers
2k views

Convert MAC address to Link-local address with bash

How can I convert a Mac address into an ipv6 Link-Local address? you have to add fe80:: at the start and insert ff:fe in the middle furthermore all leading zeros must be stripped
5
votes
2answers
3k views

What are the essential iptables rules for IPv6 to work properly?

I had a problem where I lost connectivity to a server on the IPv6 address after some time and it turned out to be caused by DHCPv6 client packets (port 546) being dropped by the default INPUT policy ...
5
votes
1answer
12k views

Is net.ipv6.conf.all.forwarding=1 equivalent to enabling forwarding for all individual interfaces?

or it is the only way to enable forwarding for IPv6? /proc/sys/net/ipv6/conf# grep '' */forwarding all/forwarding:0 default/forwarding:1 eth0/forwarding:1 lo/forwarding:1 nat64/forwarding:1 tunl0/...
5
votes
2answers
2k views

Kernel /proc ipv6 settings precedence

I'm about to connect our network to the IPv6 Internet and need to control the kernel ipv6 settings found under /proc. I know there are configurations for each interface, for all interfaces, and the ...
5
votes
1answer
1k views

IPv6 ephemeral port range

In Linux, I can get and set the range of ephemeral ports through /proc/sys/net/ipv4/ip_local_port_range: $ cat /proc/sys/net/ipv4/ip_local_port_range 32768 61000 I want to control the ephemeral ...
5
votes
1answer
4k 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, ...
5
votes
3answers
7k views

Validating IP addresses (IPv4 and IPv6)

Quite simply I'd like to verify that a string represents a valid IP address in a bash script. I think like many others I've fallen into the pitfall of trying to do this with a regular expression; ...
5
votes
1answer
749 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 ...
5
votes
0answers
132 views

Why does localhost resolve to ::1 but not 127.0.0.1

With getent hosts localhost, I only get ::1, although I expect 127.0.0.1. I have IPv6 disabled, so getting ::1 is even more surprising. To add to the confusion, when I ping localhost, pings are sent ...
5
votes
0answers
150 views

Multicast ICMPv6 comes back with conntrack state invalid

I was playing arround with the Multicast feature of IPv6. $ ping ff02::2%wlp3s0 This should normally result in an echo-reply from all the routers on your local network segment (Wikipedia - IPv6). So ...
5
votes
0answers
2k 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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