IPv6 is the successor to IPv4. Rather than 2^32 addresses (like IPv4), it has 2^128, which is 340,282,366,920,938,463,463,374,607,431,768,211,456 unique addresses (34 undecillion). IPv6 addressing is quite different to IPv4 and is not backwards compatible, but protocols that sit on top (HTTP, SSH, ...

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1answer
49 views

Firewalld blocks IPv6, ignores config

I'm trying to setup an IPv6 web-server on CentOS 7.2 with NGINX. I have tested my IPv6 connectivity outgoing and incoming - everything works. My IP, AAAA records, etc as fine as well. Essentially ...
-1
votes
1answer
50 views

Building router with one ethernet interface

Good day! I have 2 servers in datacenter and I want to use one of them as router for another instead of default gateway provided by DC. Both servers have one ethernet interface called 'eth0' with ...
0
votes
1answer
44 views

“Ipcalc -n ipv6_addr” command is giving error

I am trying to calculate network address of Ip address by using Ipcalc command. when i am using ipcalc -n ipv4 address,then it is running fine and give the network address for the IPv4. But when i ...
0
votes
1answer
16 views

Allow outgoing IPv6 connections for VPN clients

I have the OpenVPN server. A client connecting to this server receive an internal IPv4 address (10.2.52.X) and an external IPv6 address. I need to perform a masquerading (NAT) for IPv4 but I don't ...
1
vote
1answer
642 views
+200

Mikrotik: how to properly setup IPV6 routing/dhcp server

I have the following configuration in my network: ISP Router <- eth1 -> Mikrotik Router <- eth2-5 -> Internal network My ISP router receives a /64 IPV6 block that is dynamic, changing ...
0
votes
0answers
22 views

IPv6 interface not responding to neighbor solicitations, DHCP involved too

ip addr shows: 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 02:6d:5e:86:29:49 brd ff:ff:ff:ff:ff:ff inet ...
0
votes
0answers
38 views

Hyper-V vm can ping host but host cannot ping Hyper-V vm?

When ping host from hyper-v VM, it works both with ipv4 or ipv6. Pinging MyHost [fe80::3549:ee49:a75c:619c%9] with 32 bytes of data: Reply from fe80::3549:ee49:a75c:619c%9: time<1ms Reply from ...
0
votes
0answers
5 views

Kamailio as TCP-only SIP register and relay

I have a rather complicated setup in which I'd like to run a SIP server. In general, I want to run an IPv6-only Kamailio SIP-server on internal network and have outside SIP-clients be able to make ...
0
votes
0answers
28 views

IPv4/IPv6 dualstack setup in Debian/Ubuntu via preseed

I use preseed to provision my Ubuntu 16.04 installation. It has the following options to set up IPv4 or IPv6 address # Static network configuration. # # IPv4 example #d-i netcfg/get_ipaddress string ...
1
vote
1answer
24 views

How to redirect traffic through IPv6 IPSec (strongswan) gateway?

I'm trying to set up IPSec secured connection to the gateway. Have three hosts: A: eth1 - fec0:1::1/64 B: eth1 - fec0:1::2/64 eth2 - fec0:2::2/64 which is gateway between A and C; forwarding is set ...
17
votes
2answers
1k views

Is an IPv6-only MTA possible yet?

Has anyone had tried to run an IPv6-only SMTP engine? Pretty much everybody with any sense has IPv6 configured for major front-end servers. I was curious if anyone had tried to run an IPv6-only MTA ...
3
votes
3answers
5k views

sendmail can not deliver to gmail - IPv6 sending guidelines regarding PTR records not met

I am having trouble in delivering mail to google from a fresh sendmail install on ubuntu 14.04. The DNS-records seem to be fine for the ip. Something else must be wrong. Sending mail from command ...
-1
votes
0answers
24 views

How does AWS convert an IPv6 address to an IPv4 address when whitelisting “My IP” address [migrated]

I recently had to whitelist my IP address in an AWS security group using the "My IP" option. It worked perfectly and displayed an IPv4 address, but when I looked up my IP address with Google I got an ...
1
vote
1answer
220 views

OpenSSH adds <IPv6>%2 to known_hosts

When I connect to a CentOS 7 host with IPv6 my ssh client always adds <IPv6 host addr>%2 to known_hosts even though the host key for this host (with the host's IPv6 address) is already present ...
1
vote
1answer
46 views

Can Linux be made to honour IPv6 Route Advertisement preferences?

Bottom Line Up Front: I can't get a Linux box receiving RAs to use the RFC4191 "Default Router Preference" value to prefer higher-priority routes. Instead, whichever default route it learnt first is ...
1
vote
1answer
35 views

IPv6 and ESP as a next header

I'd like to know how to parse IPv6 header and get offset to TCP header and its payload. I know that IPv6 has fixed base header. I know also that there are several extension headers in IPv6 - among ...
1
vote
0answers
18 views

Delayed Ping of a link-local address with Windows 7/Server 2008 R2/Server 2012 R2

I have a strange effect here, which I do not understand. PS C:\Users\user1> ping fe80::219:bbff:fe0e:c600%16 -t Ping wird ausgeführt für fe80::219:bbff:fe0e:c600%16 mit 32 Bytes Daten: Zielhost ...
0
votes
1answer
24 views

What changes with Kerberos authentication in IPv6 when everyone has a public IPv6 Address?

How should Kerberos authentication be set up with IPv6? What implications are there when client devices each use a public, globally routeable IPv6 IP address? What changes when setup this way ...
0
votes
0answers
12 views

What changes with Kerberos Authentication in IPv6 when using NAT? [duplicate]

How should Kerberos Authentication be setup with IPv6? Of you're using NAT for IPv6 where there is a single public IPv6 address and it translates to the machines inside in the ULA range?
0
votes
0answers
26 views

Allow outgoing traffic behind ipv6 firewall behind router

I am working on configuring ipv6 traffic for a project and I am running into a problem. When I try to ssh from the machines that are behind the router into the router, it blocks the connection. I ...
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votes
1answer
61 views

IPv6 + PTR + gmail returning error

I have a problem with mail connected to gmail account. Every time when i wanna send mail i got that error: Our system has detected that this message does not meet IPv6 sending guidelines regarding ...
1
vote
0answers
38 views

IPv6 Routing // Destination unreachable: Beyond scope of source address

I want to setup Dual Stack on Customer VMs. The Router is a VM too. Running on Debian Wheezy. Overall virtualized by ESXi. IPv4 is working fine. Ping from Customer VM ping6 -c 1 heise.de PING ...
1
vote
2answers
2k views

/etc/init.d/iptables-persistent start returns fail but seems to work [closed]

I am trying to activate iptables-persistent on an Ubunutu server. Config files are located in /etc/iptables/rules.v4 /etc/iptables/rules.v6 I have installed the iptables-persistent package. ...
0
votes
1answer
33 views

Linux host does not retransmit with a lower packet size in response to ICMPv6 Packet Too Big message

I'm seeing this in Wireshark when curling this URL: On the same network, a Windows host retransmits properly, but an Android host does not. On a different network (presumably appropriately ...
0
votes
0answers
31 views

IPv4 over IPv6 IPsec tunnel

I've got two Cisco 2811 routers, both with a global static IPv6 adress, and an IPsec tunnel between them (using VTIs). Is it possible to send IPv4 traffic over this tunnel? The relevant parts of the ...
1
vote
3answers
826 views

Debian 8 resolv.conf overwritten by IPv6 autoconfiguration/DHCP when DHCP disabled

I have recently installed Debian 8 on a network with IPv6 DHCP Enabled. /etc/resolv.conf is being overwritten by the IPv6 DHCP entires continually despite the fact that all IPv6 DHCP is disabled, ...
0
votes
1answer
34 views

How to force Centos to use ipv6 interface only?

My Centos server has two virtual (Openvz) interfaces. One from these interfaces has ipv4 address configured, while the other one has the ipv6 one. In short this server is used for browsing / proxy. ...
0
votes
0answers
41 views

Ensure systemd wait for IPv6 before start service unit

When I have a service listening on a specific IPv6 address, it fails on boot, claiming that the address is still not available. This happens to every service that is listening on specific addresses. ...
1
vote
1answer
17 views

Manually Assigning Site Local IPv6 Multicast Address to DHCP Server

According to https://en.wikipedia.org/wiki/IPv6_address#Multicast_addresses, ff05::1:3 is a site local multicast address for All-dhcp-servers. Based on this, when I add the DHCP role to a Windows ...
1
vote
0answers
12 views

Assigning Prefix-Flexible Static IPv6 Addresses to Servers

Sometimes it's desirable to assign a server a static IPv6 addresses. Hand-configuring a static global unicast IPv6 address is one way to do this but necessitates manual updating any time the address ...
1
vote
2answers
428 views

djbdns/dbndns dnscache query ipv6-only nameservers?

I have (attempted to) set up dnscache on Ubuntu 14.04 (Trusty) to do dual stack for servicing requests AND querying authoritative name servers. To be clear, I'm using the dbndns package, which has ...
1
vote
1answer
78 views

SOA record in AAAA query reply when IPv6 is not supported

When I do dig AAAA to a website that doesn't support IPv6 yet, the reply has an SOA record. Is it a requirement to have the SOA record in response to a AAAA query when the service doesn't support ...
0
votes
1answer
46 views

AWS ELB with ipv6 fails on online tests

I have an ELB with ipv6 AAAA DNS configured on route 53. The problem is that the tests I used tell me it's not ok (I don't have an ipv6 connection for testing): AFAIK I don't need to configure ...
3
votes
0answers
238 views

IPv6 only server PXE provisioning

We are currently preparing for IPv6 only network deployment and struggle to find a unique server identification. In our previous setup, we used mac address as servers primary identification. We were ...
2
votes
1answer
675 views

IPv4 header vs IPv6 header size

Just wondering from looking at that picture if Total Length = Payload Length and the IPv6 header is bigger, does that mean IPv4 packets can contain more data?
8
votes
2answers
814 views

Tuning Linux's IPv6 stack

I'm working on a Linux network deice, and there are some TCP/IP settings that don't seem to have IPv6 equivalents. IP forwarding is a common setting, and available in both stacks net.ipv4.ip_forward ...
0
votes
0answers
26 views

IPv6 Ping is unsuccessful when IP is obtained from DHCP server

I just faced this problem and it's driving me crazy. I have DHCP server for both IPv4 and IPv6. IPv4 works like a charm but the problem is IPv6. My client gets IPv6 (fc50::a9 to be exact) from DHCP ...
0
votes
0answers
28 views

Very slow outgoing requests, from **some** servers

In this case, it's an HTTP request to https://www.instagram.com/, but it has happened before like this. From my home (Ubuntu, i686) server it's very fast (~ 0.3 sec). From my online, modern (Ubuntu, ...
39
votes
14answers
15k views

Why would you use IPv6 internally?

Of course, I realize the need to go to IPv6 out on the open Internet since we are running out of addresses, but I really don't understand why there is any need to use it on an internal network. I have ...
0
votes
0answers
53 views

IPv6 is not working between two OpenWRT devices

I have 2 problems lately regarding IPv6: My ISP doesn't provide an IPv6 prefix (even with modem in bridge, and yes the ISP supports) so, I'm using SIXXS tunnel , it doesn't attribute IPv6 to another ...
11
votes
2answers
1k views

IPv6 subnetting a /64 - what will break, and how to work around it?

In IPv6, you are not supposed to subnet to anything smaller than a /64 (RFC 5375). Among other things, SLAAC does not work with smaller subnets, and apparently also some other features will break. ...
0
votes
0answers
58 views

How to avoid curl trying IPv6 name resolution

From a docker container when I try to curl 'another container name', curl first tries to resolve the name to IPv6. This causes few seconds delay because the web server is not reachable over ipv6. I ...
0
votes
2answers
40 views

IPv6 DNS Connectivity through IPv6

My clients are using IPv4 in the USA. Their ISP is not ready for IPv6 yet. My public web server is on only IPv6. It is registered with a DNS Provider(GoDaddy) that is IPv4 and IPv6 enabled. Can my ...
0
votes
0answers
123 views

IPv6: Destination unreachable: Address unreachable

My server can't ping/reach any other outside. ping6 works for my local fe80::468... address as well as the 2a01:4f8..., but not for fe80::1! Errors/Troubles/Issues: ip neigh show fe80::1 dev eth0 ...
0
votes
0answers
56 views

HAProxy configuration problems (with source directive)

I have HAProxy setup to listen on a public IPv4 address (1.2.3.4), it is supposed to proxy all requests to my b_http backend. The back-end has a source line that makes it connect to the server/site ...
2
votes
0answers
44 views

Is it possible to configure HAProxy to listen on IPV4, but send the request using IPV6? [closed]

Trying to configure HAProxy to listen for requests on port ipv4(Port 80) but proxy the request through eth1 to a server using ipv6. The request must be show the ipv6 address for the request. We don't ...
0
votes
1answer
38 views

Fixed Size of IPv6 SLAAC

My confusion with IPv6 SLAAC is that the router provides the network prefix, and the host generates its own part using EUI-64, which means it is always going to be a 64-bit address. Now, SLAAC is ...
1
vote
1answer
54 views

Understanding IPv6 Address

My IPv6 address is like this (some digits changed): 2001:569:78f0:ca00:bcaa:d016:4 ...as reported by whatismyipaddress.com. This is strange because I understand that there should be eight blocks ...
1
vote
1answer
66 views

HTTPD listening in IPv6, according netstat, but reacheable in IPv4

Using Openstack, I have a Web GUI (horizon) hosted on my server (HTTPS). When I do a netstat -lt | grep https, I have: tcp6 0 0 [::]:https [::]:* LISTEN ...
4
votes
3answers
9k views

Why does NTP daemon keep listening on UDP6?

I have a clean Debian 7 installation, and I manually entered the following lines in /etc/ntp.conf: interface ignore wildcard interface listen <local_nic_ip> Hoping that NTP will no longer ...