ipsec site-to-site merge doar intr-un sens

Salutare,

Am urmatoarele servere:
S1: centos 7
eth0 192.168.0.1
eth1 198.51.100.2, gw 198.51.100.2
iptables allow INPUT de la 203.0.113.2, UDP 4500 si 500

S2: ubuntu 16.04
eth0 10.200.1.2, gw 10.200.1.2, nat-uit in spatele lui 203.0.113.1
(forwardat UDP 4500 si 500)
iptables allow all

ipsec-ul zice pe amandoua ca totul e ok:
[root@S1 ~]# strongswan status
Security Associations (1 up, 0 connecting):
   S1-S2[40]: ESTABLISHED 47 minutes ago, 198.51.100.2[S1]...203.0.113.1[S2]
   S1-S2{105}:  INSTALLED, TUNNEL, reqid 36, ESP in UDP SPIs: c23ec2d5_i
ccc36949_o, IPCOMP CPIs: c755_i e5b8_o
   S1-S2{105}:   192.168.0.1/32 === 10.200.1.2/32
root@S2:~# ipsec status
Security Associations (1 up, 0 connecting):
   S1-S2[70]: ESTABLISHED 44 minutes ago, 10.200.1.2[S2]...198.51.100.2[S1]
   S1-S2{212}:  INSTALLED, TUNNEL, reqid 69, ESP in UDP SPIs: ccc36949_i
c23ec2d5_o, IPCOMP CPIs: e5b8_i c755_o
   S1-S2{212}:   10.200.1.2/32 === 192.168.0.1/32
Rutele sunt si ele ok:
root@S1:~# ip route list table 220
192.168.0.1 via 10.200.1.1 dev eth0  proto static  src 10.200.1.2
[root@S2 ~]# ip route list table 220
10.200.1.2 via 198.51.100.1 dev eth1  proto static  src 192.168.0.1

Dar de pe S2 merg conexiunile spre S1 (ping, tcp, samd; in ambele sensuri
), dar nu si invers. Adica nu ajung deloc pachetele initiate de S1 la S2,
dar ajung reply-urile lui S1 la query-urile lui S2:
[root@S1 ~]# ping -q -c 1 10.200.1.2
PING 10.200.1.2 (10.200.1.2) 56(84) bytes of data.

--- 10.200.1.2 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms
root@S2:~# ping -q -c 1 192.168.0.1
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.

--- 192.168.0.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 6.423/6.423/6.423/0.000 ms

Cum experienta mea cu ipsec e foarte limitat, puteti sa dati un ochi pe
conf-urile de ipsec, sa-mi spuneti daca am ratat ceva? Sau orice alt sfat?

Merci.

PS: numerele alea dintre paranteze drepte/acolade e normal sa creasca la
fiecare reuathentication/rekeying?

[root@S1 ~]# cat /etc/strongswan/ipsec.conf
config setup
  charondebug="ike 2, knl 2, cfg 2, net 2, esp 2, dmn 2,  mgr 2"

conn %default
  authby=secret
  auto=start
  compress=yes
  dpdaction=restart
  dpddelay=300s
  dpdtimeout=10s

esp=aes128-aes256-sha1-sha256-modp2048-modp4096-modp1024,aes128-sha1,aes128-sha1-modp1024,aes128-sha1-modp1536,aes128-sha1-modp2048,aes128-sha256,aes128-sha256-ecp256,aes128-sha256-modp1024,aes128-sha256-modp1536,aes128-sha256-modp2048,aes128gcm12-aes128gcm16-aes256gcm12-aes256gcm16-modp2048-modp4096-modp1024,aes128gcm16,aes128gcm16-ecp256,aes256-sha1,aes256-sha256,aes256-sha256-modp1024,aes256-sha256-modp1536,aes256-sha256-modp2048,aes256-sha256-modp4096,aes256-sha384,aes256-sha384-ecp384,aes256-sha384-modp1024,aes256-sha384-modp1536,aes256-sha384-modp2048,aes256-sha384-modp4096,aes256gcm16,aes256gcm16-ecp384,3des-sha1!

ike=aes128-sha1-modp1024,aes128-sha1-modp1536,aes128-sha1-modp2048,aes128-sha256-ecp256,aes128-sha256-modp1024,aes128-sha256-modp1536,aes128-sha256-modp2048,aes256-aes128-sha256-sha1-modp2048-modp4096-modp1024,aes256-sha1-modp1024,aes256-sha256-modp1024,aes256-sha256-modp1536,aes256-sha256-modp2048,aes256-sha256-modp4096,aes256-sha384-ecp384,aes256-sha384-modp1024,aes256-sha384-modp1536,aes256-sha384-modp2048,aes256-sha384-modp4096,aes256gcm16-aes256gcm12-aes128gcm16-aes128gcm12-sha256-sha1-modp2048-modp4096-modp1024,3des-sha1-modp1024!
  ikelifetime=60m
  keylife=30m
  keyexchange=ikev2
  keingtries=%forever
  margintime=3m
  mobike=no

conn ICI-MSADO
  left=198.51.100.2
  leftsubnet=192.168.0.1/32
  leftid=@S1
  leftid2=@S1
  leftfirewall=yes
  right=203.0.113.1
  rightsubnet=10.200.1.2/32
  rightid=@S2
  rightid2=@S2
  rightfirewall=yes


root@gw-01:~# cat /etc/ipsec.conf
config setup
  charondebug="ike 2, knl 2, cfg 2, net 2, esp 2, dmn 2,  mgr 2"

conn %default
  authby=secret
  auto=start
  compress=yes
  dpdaction=clear
  dpddelay=300s
  dpdtimeout=10s

esp=aes128-aes256-sha1-sha256-modp2048-modp4096-modp1024,aes128-sha1,aes128-sha1-modp1024,aes128-sha1-modp1536,aes128-sha1-modp2048,aes128-sha256,aes128-sha256-ecp256,aes128-sha256-modp1024,aes128-sha256-modp1536,aes128-sha256-modp2048,aes128gcm12-aes128gcm16-aes256gcm12-aes256gcm16-modp2048-modp4096-modp1024,aes128gcm16,aes128gcm16-ecp256,aes256-sha1,aes256-sha256,aes256-sha256-modp1024,aes256-sha256-modp1536,aes256-sha256-modp2048,aes256-sha256-modp4096,aes256-sha384,aes256-sha384-ecp384,aes256-sha384-modp1024,aes256-sha384-modp1536,aes256-sha384-modp2048,aes256-sha384-modp4096,aes256gcm16,aes256gcm16-ecp384,3des-sha1!

ike=aes128-sha1-modp1024,aes128-sha1-modp1536,aes128-sha1-modp2048,aes128-sha256-ecp256,aes128-sha256-modp1024,aes128-sha256-modp1536,aes128-sha256-modp2048,aes256-aes128-sha256-sha1-modp2048-modp4096-modp1024,aes256-sha1-modp1024,aes256-sha256-modp1024,aes256-sha256-modp1536,aes256-sha256-modp2048,aes256-sha256-modp4096,aes256-sha384-ecp384,aes256-sha384-modp1024,aes256-sha384-modp1536,aes256-sha384-modp2048,aes256-sha384-modp4096,aes256gcm16-aes256gcm12-aes128gcm16-aes128gcm12-sha256-sha1-modp2048-modp4096-modp1024,3des-sha1-modp1024!
  ikelifetime=60m
  keylife=30m
  keyexchange=ikev2
  keingtries=%forever
  margintime=3m
  mobike=no

conn ICI-MSADO
  left=10.200.1.2
  leftsubnet=10.200.1.2/32
  leftid=@S2
  leftid2=@S2
  leftnexthop=%defaultroute
  rightfirewall=yes
  right=198.51.100.2
  rightsubnet=192.168.0.1/32
  rightid=@S1
  rigthid2=@S1
  rightfirewall=yes

-- 
Beware of programmers who carry screwdrivers.