Hot answers tagged

29 votes

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

Any IPv6 address that starts with fe80: is the equivalent of IPv4 169.254.*.* address, i.e. it's a link-local address, reachable only in the network segment it's directly connected to, using the NIC ...
user avatar
  • 68.6k
25 votes
Accepted

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

Avahi is the opensource implementation of Bonjour/Zeroconf. excerpt - http://avahi.org/ Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol ...
user avatar
  • 346k
22 votes
Accepted

How to add ipv6 default route

You need to add the route to the gateway first: ip -6 route add 2004::3 dev eth0
user avatar
22 votes

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

[::] indicate all ipv6 addresses. 4443 is a port number. So if a service is bound to [::]:4443 it'll be listening to all ipv6 addresses available in your system. It's similar to listening 0.0.0.0 for ...
user avatar
  • 2,030
20 votes

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

The reason for this is because all IPv4 addresses are also IPv6 addresses. A small range of IPv6 addresses was set aside to be used for one-to-one mapping of IPv4 addresses. For example, the IPv4 ...
user avatar
  • 67.6k
20 votes
Accepted

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

By default if you don't specify address to Apache Listen parameter, it handles ipv6 address using IPv4-mapped IPv6 addresses. You can take a look in Apache ipv6 The output of netstat doesn't mean ...
user avatar
  • 2,588
19 votes
Accepted

How to get Pi-Hole to work with IPv6?

I got it working. Here's what I did: When I initially set up my Pi-Hole, I only had IPv4 on my system. Thus Pi-Hole only downloaded IPv4-capable blacklists. So I turned IPv6 on on my home router, and ...
user avatar
  • 2,249
17 votes
Accepted

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

Using tcpdump which is installed by default on many distributions: tcpdump -n -i eth0 icmp6 will show you all ICMPv6 packets of which - under usual conditions - almost all are neighbor discovery ...
user avatar
  • 7,019
16 votes
Accepted

What is the IPv6 equivalent for 127.0.0.0/8

From Wikipedia: IPv4 network standards reserve the entire 127.0.0.0/8 address block for loopback purposes. That means any packet sent to one of those 16,777,214 addresses (127.0.0.1 through 127.255....
user avatar
  • 292
16 votes
Accepted

IPv6 addressing, dynamic prefix static local part

There are two ways to do this. One is the easy way and one is the hard way. The easy way is to run a DHCPv6 server on your network and assign host addresses to each device yourself. Or let the server ...
user avatar
15 votes
Accepted

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

-4/-6 tells dig to only use IPv4/IPv6 connectivity to carry your query to the nameserver - it doesn't change whether to query for A records(IPv4) or AAAA records(IPv6) if that's what you intended. If ...
user avatar
  • 1,599
14 votes

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

According to RFC 4291, Section 2.7: Multicast Addresses, the first 8 bits (FF in FF0X) at the beginning of identifies the address as a muticast address. The flags, the next 4 bits, (the first 0 in ...
user avatar
  • 45.6k
13 votes
Accepted

wget uses ipv6 address and takes too long to complete

curl and wget do not use different mechanisms for resolving domains (they're using getaddrinfo()). However, curl implements a fast fallback algorithm to improve the user experience in cases where IPv6 ...
user avatar
12 votes
Accepted

Routing public ipv6 traffic through openvpn tunnel

You need to tell your router to use your server for this VPN subnet: the correct solution to your problem is to add a route on the router for the OpenVPN subnet. If you can't do this because you can'...
user avatar
  • 1,668
12 votes
Accepted

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

If you want to create a whole IPv6 address from a MAC (and a given prefix), you could use the excellent ipv6calc tool by Peter Bieringer. The following command creates a link-local IPv6 address (fe80:...
user avatar
  • 3,394
12 votes
Accepted

Resolving hostname takes 5 seconds

Short answer: A workaround is forcing glibc to reuse a socket for look up of the AAAA and A records, by adding a line to /etc/resolv.conf: options single-request-reopen The real cause of this issue ...
user avatar
  • 2,344
12 votes

Add IPv6 address to existing IPv4 interface not working

Your ifup probably doesn't run because the interface already has the IPv4 address and it can't add it twice. It will not even reach the IPv6 line. If you can you should bring the interface down so all ...
user avatar
11 votes

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

When connecting to an IPv6 link-local address you need to specify through which link to reach it, as seen from the client system. The same link-local addresses are used on every link, so the client ...
user avatar
11 votes
Accepted

Is it possible to implement IPv6 on a virtual interface (eth0:1 interface) in Linux?

IPv4 implementations originally only supported one address per interface, which is why virtual interfaces were invented so you can add multiple addresses on the same physical interface. IPv6 supports ...
user avatar
10 votes
Accepted

Permanently disable IPv6, for a given interface?

First, edit /etc/default/grub and find the line: GRUB_CMDLINE_LINUX="" and change the line to say this instead (this will disable ipv6 completely): GRUB_CMDLINE_LINUX="ipv6.disable=1" ...
user avatar
  • 1,392
10 votes

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

Yes, that suggests that you do not have IPv6 connectivity. If you want to obtain an IPv6 address for google rather than using IPv6 to obtain an address for google, you want dig -t aaaa google.com ...
user avatar
  • 7,898
10 votes
Accepted

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

Looks like indeed it is designed to work differently compared to IPv4's */forwarding and all/forwarding: From https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt: conf/all/forwarding - ...
user avatar
  • 5,176
10 votes

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

It's a bind designation to port 4443 of all interfaces that support IPv6. It is equivalent to [0000:0000:0000:0000:0000:0000:0000:0000]:4443.
user avatar
10 votes
Accepted

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

The address space allocated to link-local addresses is fe80::/10, but the next 54 bits are defined to be all zeroes, so the effective range is fe80::/64. Which puts it in line with the usual custom ...
user avatar
  • 117k
9 votes
Accepted

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

By default sshd uses ipv4 and ipv6. You can configure the protocol sshd uses through the AddressFamily directive in /etc/ssh/sshd_config For ipv4 & ipv6 (default) AddressFamily any For ipv4 ...
user avatar
  • 4,786
9 votes
Accepted

i don't get ipv6. Why cannot I ping ipv6.google.com?

You have only Link-Local, non routable ipv6 (fe80::/10). So You have no public routable IPv6. In this configuration You can make ipv6 connect only to Link-Local addresses in same L2 segment.
user avatar
  • 583
9 votes
Accepted

does :::80 in netstat output means only ipv6 or ipv6+ipv4?

A listening socket that is bound to ::, i.e. any address IPv6 address (INADDR6_ANY), may or may not also listen to connections using IPv4. This depends from several things: Some operating systems are ...
user avatar
9 votes

unable to ping ipv6 device with linklocal address

[You should check your firewall/ip6tables rules. That should just work -- assuming, of course, that the two devices are connected directly] When pinging a link-local ipv6 address, you could also ...
user avatar
  • 28.5k
9 votes
Accepted

How can you run OpenVPN client inside a docker container?

I got it working. It looks like I have to enable IPv6 manually: docker run -it --rm --cap-add=NET_ADMIN --device /dev/net/tun \ --sysctl net.ipv6.conf.all.disable_ipv6=0 -v $PWD:$PWD \ ...
user avatar
  • 163
8 votes

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

Actually, it's slightly more interesting Basically, even if you completely disable IPv6, some sockets will get identified as "TCP6/UDP6" due to curious kernel reasons. I noticed it after I ran ...
user avatar

Only top scored, non community-wiki answers of a minimum length are eligible