Dear list,

I'm new to IPSec and need a hand trying to set up a VPN with a foreign institution.

Basically I have a single host offering some services that should also act as the IPSec client / left side host. This is the only left-side host that must be accessible from the right-side network.

On this left-side server I installed SUSE SLES 12 SP 1 with Strongswan 5.1.3.

The right side uses a commercial solution (Fotinet Fortigate).

Using this configuration I can establish the IPSec connection:

*ipsec.conf*

config setup
        charondebug="all"
        uniqueids=yes
        strictcrlpolicy=no

conn %default
conn tunnel
        left=141.a.b.c
        leftsubnet=192.168.66.0/24
        lefthostaccess=yes
        leftsourceip=%config
        right=193.d.e.f
        rightsubnet=192.168.19.0/24
        ike=aes256-sha256-prfsha256-ecp521!
        esp=aes256-sha256!
        keyingtries=0
        ikelifetime=28800s
        lifetime=14400s
        dpddelay=30
        dpdtimeout=120
        dpdaction=restart
        authby=secret
        auto=start
        keyexchange=ikev2
        type=tunnel

The connection seems to be ok:
**

*ipsec statusall*

Status of IKE charon daemon (strongSwan 5.1.3, Linux 3.12.74-60.64.124-default, x86_64):
  uptime: 21 hours, since Feb 10 16:04:02 2020
  malloc: sbrk 2838528, mmap 0, used 671024, free 2167504
  worker threads: 10 of 16 idle, 6/0/0/0 working, job queue: 0/0/0/0, scheduled: 5   loaded plugins: charon ldap pkcs11 aes des blowfish rc2 sha1 sha2 md4 md5 random nonce x509 revocation constraints pubkey pkcs1 pkcs7 pkcs8 pkcs12 pgp dnskey sshkey pem openssl gcrypt af-alg fips-prf gmp agent xcbc cmac hmac ctr ccm gcm curl soup attr kernel-netlink resolve socket-default farp stroke smp updown eap-identity eap-sim eap-sim-pcsc eap-aka eap-aka-3gpp2 eap-simaka-pseudonym eap-simaka-reauth eap-md5 eap-gtc eap-mschapv2 eap-dynamic eap-radius eap-tls eap-ttls eap-peap eap-tnc xauth-generic xauth-eap xauth-pam tnc-imc tnc-imv tnc-tnccs tnccs-20 tnccs-11 tnccs-dynamic dhcp certexpire led duplicheck radattr addrblock unity
Listening IP addresses:
  141.a.b.c
  192.168.66.1
Connections:
      tunnel:  141.a.b.c...193.d.e.f  IKEv2, dpddelay=30s
      tunnel:   local:  [141.a.b.c] uses pre-shared key authentication
      tunnel:   remote: [193.d.e.f] uses pre-shared key authentication
      tunnel:   child:  192.168.66.0/24 === 192.168.19.0/24 TUNNEL, dpdaction=restart
Security Associations (2 up, 0 connecting):
      tunnel[4]: ESTABLISHED 6 hours ago, 141.a.b.c[141.a.b.c]...193.d.e.f[193.d.e.f]       tunnel[4]: IKEv2 SPIs: fd1ce3e19651ea83_i b0e8873d947ad4e8_r*, pre-shared key reauthentication in 76 minutes       tunnel[4]: IKE proposal: AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_521
      tunnel[1]: CONNECTING, 141.a.b.c[141.a.b.c]...193.d.e.f[193.d.e.f]
      tunnel[1]: IKEv2 SPIs: 38a8d3b8593af26a_i* 77f1ac5ed3598059_r
      tunnel[1]: IKE proposal: AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_521       tunnel[1]: Tasks active: IKE_CERT_PRE IKE_AUTH IKE_CERT_POST IKE_CONFIG CHILD_CREATE IKE_AUTH_LIFETIME IKE_MOBIKE


However, there is some sort of routing problem. In either direction, packets travel through the tunnel, are seen on the other side,  but the responses never come back.

The IP address of the left machine:

*ip addr*

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:x:x:x:x:x brd ff:ff:ff:ff:ff:ff
    inet 141.a.b.c/22 brd 141.a.b.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet 192.168.66.1/24 brd 192.168.66.255 scope global eth0:1
       valid_lft forever preferred_lft forever
    inet6 fe::0:f:f7:b/64 scope link
       valid_lft forever preferred_lft forever

The routing tables:

*ip route list table all*

192.168.19.0/24 via 192.168.66.1 dev eth0  table 220  proto static  src 192.168.66.1
default via 141.a.b.1 dev eth0
141.a.b.0/22 dev eth0  proto kernel  scope link  src 141.a.b.c
192.168.66.0/24 dev eth0  proto kernel  scope link  src 192.168.66.1
broadcast 127.0.0.0 dev lo  table local  proto kernel  scope link src 127.0.0.1 local 127.0.0.0/8 dev lo  table local  proto kernel  scope host src 127.0.0.1 local 127.0.0.1 dev lo  table local  proto kernel  scope host  src 127.0.0.1 broadcast 127.255.255.255 dev lo  table local  proto kernel  scope link  src 127.0.0.1 broadcast 141.a.b.0 dev eth0  table local  proto kernel  scope link  src 141.a.b.c local 141.a.b.c dev eth0  table local  proto kernel  scope host src 141.a.b.c broadcast 141.a.b.255 dev eth0  table local  proto kernel  scope link  src 141.a.b.c broadcast 192.168.66.0 dev eth0  table local  proto kernel  scope link  src 192.168.66.1 local 192.168.66.1 dev eth0  table local  proto kernel  scope host  src 192.168.66.1 broadcast 192.168.66.255 dev eth0  table local  proto kernel scope link  src 192.168.66.1 unreachable default dev lo  table unspec  proto kernel  metric 4294967295  error -101
local ::1 dev lo  proto kernel  metric 256
fe80::/64 dev eth0  proto kernel  metric 256
unreachable default dev lo  table unspec  proto kernel  metric 4294967295  error -101
local ::1 dev lo  table local  proto none  metric 0
local f::2:f:7:b8 dev lo  table local  proto none  metric 0
ff00::/8 dev eth0  table local  metric 256
unreachable default dev lo  table unspec  proto kernel  metric 4294967295  error -101

*iptables -nL*

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination


I would really appreciate if someone could give a hint or two on how to solve this issue!

Kind regards
Alvaro


--
Dipl.-Inf. Alvaro Aguilera
Wissenschaftlicher Mitarbeiter

Technische Universität Dresden
Zentrum für Informationsdienste und Hochleistungsrechnen
Verteiltes und Datenintensives Rechnen

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