P.S.
Forgot to mention, the VPN client is Windows 10 Professional version 21H2:
Kind regards,
mt
On 5.10.2022. 15:58, Mirsad Goran Todorovac wrote:
Hi all,
Our VPN worked well until we moved to IPv6, and now it works only with
IPv6 disabled,
which is not practical (change of network settings resets all Putty
terminal and all ssh connections
among others ... ).
The configuration is as follows:
conn MYCONN-ikev2-ipv6-cp
# The server's actual IP goes here - not elastic IPs
left=2001:b68:2:2600::3
leftcert=magrf.grf.hr
[email protected]
leftsendcert=always
leftsubnet=0::/0
leftrsasigkey=%cert
# Clients
right=%any
# your addresspool to use - you might need NAT rules if
providing full internet to clients
rightaddresspool=fd00:2600:1000:0000/64
# optional rightid with restrictions
# rightid="O=GRF-UNIZG,CN=win7client.grf.hr"
rightca=%same
rightrsasigkey=%cert
#
# connection configuration
# DNS servers for clients to use
modecfgdns=2001:b68:2:2600::3,2606:4700:4700::1001
narrowing=yes
# recommended dpd/liveness to cleanup vanished clients
dpddelay=30
dpdtimeout=120
dpdaction=clear
auto=add
ikev2=insist
rekey=no
# Set ikelifetime and keylife to same defaults windows has
# ikelifetime=8h
# keylife=2h
ms-dh-downgrade=yes
esp=aes_gcm256,aes_gcm128,aes256-sha2_512,aes128-sha2_512,aes256-sha1,aes128-sha1
#
esp=aes_gcm256-null,aes_gcm128-null,aes256-sha2_512,aes128-sha2_512,aes256-sha1,aes128-sha1,aes_gcm256-null;modp1024
# ikev2 fragmentation support requires libreswan 3.14 or newer
fragmentation=yes
# optional PAM username verification (eg to implement
bandwidth quota
# pam-authorize=yes
authby=rsa-sha1
hostaddrfamily=ipv6
clientaddrfamily=ipv6
I am using a small script that should allow NPT to the VPN-allocated
addr range:
#!/bin/bash
# 2022-10-05 mtodorov
GWY_EXTERNAL=2001:b68:2:2600::3
EXTERNAL=2001:b68:2:2600::/64
INTERNAL=fd00:2600:1000:0000::/64
case "$1" in
start)
modprobe ip6table_mangle
modprobe ip6t_NPT
ip6tables -t mangle -A PREROUTING \! -d $GWY_EXTERNAL
-i enp1s0 -j DNPT --src-pfx $EXTERNAL --dst-pfx $INTERNAL
ip6tables -t mangle -A POSTROUTING -s $INTERNAL -o
enp1s0 -j SNPT --src-pfx $INTERNAL --dst-pfx $EXTERNAL
;;
stop)
ip6tables -t mangle -D PREROUTING \! -d $GWY_EXTERNAL
-i enp1s0 -j DNPT --src-pfx $EXTERNAL --dst-pfx $INTERNAL
ip6tables -t mangle -D POSTROUTING -s $INTERNAL -o
enp1s0 -j SNPT --src-pfx $INTERNAL --dst-pfx $EXTERNAL
sleep 1
modprobe -r ip6t_NPT
modprobe -r ip6table_mangle
;;
*) echo "Usage $0: start | stop"
esac
The result is:
root@magrf:~# ip6tables-save
# Generated by ip6tables-save v1.8.7 on Wed Oct 5 15:53:29 2022
*mangle
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING ! -d 2001:b68:2:2600::3/128 -i enp1s0 -j DNPT --src-pfx
2001:b68:2:2600::/64 --dst-pfx fd00:2600:1000::/64
-A POSTROUTING -s fd00:2600:1000::/64 -o enp1s0 -j SNPT --src-pfx
fd00:2600:1000::/64 --dst-pfx 2001:b68:2:2600::/64
COMMIT
# Completed on Wed Oct 5 15:53:29 2022
# Warning: ip6tables-legacy tables present, use ip6tables-legacy-save
to see them
root@magrf:~#
The session log is here:
https://magrf.grf.hr/~mtodorov/tmp/ikev2-ipv6-20221005-01.log
I hope this helps.
It seems to me that Libreswan attempts to retransmit to the VPN client
too early withing the same second?
Could that be a bug or is it a mistake in configuration?
Thank you.
Kind regards,
mt
--
Mirsad Todorovac
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb
Republic of Croatia, the European Union
--
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
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