How to properly connect an IPv6 tunnel from Hurricane Electric?

Question

iptables

GIVEN:
--------

• VPS with Ubuntu 16.04.2 LTS with latest updates
  
• white static IPv4 78.155.219.100 from selectel
  

NEXT:
---------

• Docker was installed according to this off-line instruction and is mentioned only because it has its own network interface.
  
• A 6to4 tunnel has been raised following this simple instruction and is working successfully. IPv6 2002:4e9b:db64::1
  
• A Hurricane Electric account was registered, and Create Regular Tunnel was requested, an additional /48 subnet was also requested in addition to /64 (but I can refuse /48, it doesn’t matter)
  

Received parameters:

Example Configurations

auto he-ipv6
iface he-ipv6 inet6 v4tunnel
address 2001:470:1f0a:b87::2
netmask 64
endpoint 216.66.80.30
local 78.155.219.100
ttl 255
gateway 2001:470:1f0a:b87::1

I restart the server.

PROBLEM:
---------------

• IPv6 2001:470:1f0b:b7f::1 and IPv6 2001:470:76b7::1 are not accessible from the Internet and do not respond to pings
  
• All that goes through the he-ipv6 tunnel is a ping to Server IPv6 Address: 2001:470:1f0a:b87::1 and nothing else
  
• Server responds to sudo ifup he-ipv6

  add tunnel "sit0" failed: No buffer space available
  Failed to bring up he-ipv6.

  
  
• sudo ifconfig
  clicked to see

  docker0 Link encap:Ethernet HWaddr 02:42:89:93:d3:d6
  inet addr:172.17.0.1 Bcast:0.0.0.0 Mask:255.255.0.0
  UP BROADCAST MULTICAST MTU:1500 Metric:1
  RX packets:0 errors:0 dropped:0 overruns:0 frame:0
  TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:0
  RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
  
  ens3 Link encap:Ethernet HWaddr 00:60:a8:b2:d7:ba
  inet addr:78.155.219.100 Bcast:78.155.219.255 Mask:255.255.255.0
  inet6 addr: fe80::260:a8ff:feb2:d7ba/64 Scope:Link
  UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
  RX packets:21433 errors:0 dropped:0 overruns:0 frame:0
  TX packets:2214 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:1000
  RX bytes:1355887 (1.3 MB) TX bytes:392677 (392.6 KB)
  
  he-ipv6 Link encap:IPv6-in-IPv4
  inet6 addr: 2001:470:1f0a:b87::2/64 Scope:Global
  inet6 addr: fe80::4e9b:db64/64 Scope:Link
  UP POINTOPOINT RUNNING NOARP MTU:1480 Metric:1
  RX packets:48 errors:0 dropped:0 overruns:0 frame:0
  TX packets:21 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:1
  RX bytes:4992 (4.9 KB) TX bytes:2184 (2.1 KB)
  
  lo Link encap:Local Loopback
  inet addr:127.0.0.1 Mask:255.0.0.0
  inet6 addr: ::1/128 Scope:Host
  UP LOOPBACK RUNNING MTU:65536 Metric:1
  RX packets:164 errors:0 dropped:0 overruns:0 frame:0
  TX packets:164 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:1
  RX bytes:12256 (12.2 KB) TX bytes:12256 (12.2 KB)
  
  tun6to4 Link encap:IPv6-in-IPv4
  inet6 addr: 2002:4e9b:db64::1/16 Scope:Global
  inet6 addr: ::78.155.219.100/96 Scope:Compat
  UP RUNNING NOARP MTU:1480 Metric:1
  RX packets:3 errors:0 dropped:0 overruns:0 frame:0
  TX packets:13 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:1
  RX bytes:312 (312.0 B) TX bytes:1352 (1.3 KB)

  
  
• sudo nano /etc/network/interfaces
  clicked to see

  # This file describes the network interfaces available on your system
  # and how to activate them. For more information, see interfaces(5).
  
  source /etc/network/interfaces.d/*
  
  # The loopback network interface
  auto lo
  iface lo inet loopback
  
  # The primary network interface
  auto ens3
  iface ens3 inet static
  address 78.155.219.100
  netmask 255.255.255.0
  gateway 78.155.219.1
  dns-nameservers 8.8.8.8 77.88.8.8
  
  ##############################
  # https://6to4.ru/debian/
  
  auto tun6to4
  iface tun6to4 inet6 v4tunnel
  pre-up modprobe ipv6
  address 2002:4e9b:db64::1
  netmask 16
  gateway ::192.88.99.1
  endpoint any
  local 78.155.219.100
  # If you have set up an IPv6-capable firewall (and you should),
  # it can be enabled by using an "up" rule, such as the example below.
  # up /usr/local/sbin/ipv6firewall.sh tun6to4
  
  ##############################
  # https://tunnelbroker.net/
  
  auto he-ipv6
  iface he-ipv6 inet6 v4tunnel
  address 2001:470:1f0a:b87::2
  netmask 64
  endpoint 216.66.80.30
  local 78.155.219.100
  ttl 255
  gateway 2001:470:1f0a:b87::1
  
  ##############################
  
  

What am I doing wrong? Whose side is the problem? In which direction to dig?

UPD_1
Setting up the tunnel was practically limited to editing /etc/network/interfaces and restarting the VPS.

UPD_2
What is radvd and what to cook it with - I didn't know.

Answer 1

ip -6 route add 2000::/3 dev he-ipv6
or try to do everything manually and see the errors:

ip tunnel add he-ipv6 mode sit remote 216.66.80.30 local 78.155.219.100 ttl 255
ip link set he-ipv6 up
ip addr add 2001:470:1f0a:b87::2/64 dev he-ipv6
ip -6 route add 2000::/3 dev he-ipv6

Assign an address to an interface in your range:
Test:

curl --interface 2001:470:1f0b:b7f::11 "http://myexternalip.com/raw"