Bug #737
Split tunneling works in Android but not in iOS, OSX and Windows
Description
Hi!
I have a VPN server with strongSwan U5.1.2/K3.13.0-32-generic which I want to enable split tunneling.
All platforms can access the VPN server and can browse the internet when split tunneling is disabled (leftsubnet=0.0.0.0/0).
But when I try to set several subnets in the leftsubnet to enable the split tunneling some issues occurred.
I also added leftfirewall=yes in my config and issued this iptables rules (iptables -t nat -A POSTROUTING -s 172.16.16.0/24 -o eth0 -m policy --dir out --pol ipsec -j ACCEPT &&
iptables -t nat -A POSTROUTING -s 172.16.16.0/24 -o eth0 -j MASQUERADE) when I enabled the split tunneling.
- In Windows, I can connect to the VPN but can't browse the internet.
- In iOS, I can connect to the VPN and can also browse the web but not the sites included in the leftsubnet.
- In OSX, VPN connection is established but destroyed immediately.
I don't have any issues for Android though and split tunnel works as expected.
Tested platforms:
- Android 4.0+
- iOS 8.0.2
- Windows 7 SP1 x64
- OS X 10.9.5
Here's how my current config looks:
# ipsec.conf - strongSwan IPsec configuration file
config setup
uniqueids=never
# strictcrlpolicy=yes
charondebug="cfg 2, dmn 2, ike 2, net 2"
conn %default
ike=aes128-sha256-ecp256,aes256-sha384-ecp384,aes128-sha256-modp2048,aes128-sha1-modp2048,aes256-sha384-modp4096,aes256-sha256-modp4096,aes256-sha1-modp4096,aes128-sha256-modp1536,aes128-sha1-modp1536,aes256-sha384-modp2048,aes256-sha256-modp2048,aes256-sha1-modp2048,aes128-sha256-modp1024,aes128-sha1-modp1024,aes256-sha384-modp1536,aes256-sha256-modp1536,aes256-sha1-modp1536,aes256-sha384-modp1024,aes256-sha256-modp1024,aes256-sha1-modp1024!
esp=aes128gcm16-ecp256,aes256gcm16-ecp384,aes128-sha256-ecp256,aes256-sha384-ecp384,aes128-sha256-modp2048,aes128-sha1-modp2048,aes256-sha384-modp4096,aes256-sha256-modp4096,aes256-sha1-modp4096,aes128-sha256-modp1536,aes128-sha1-modp1536,aes256-sha384-modp2048,aes256-sha256-modp2048,aes256-sha1-modp2048,aes128-sha256-modp1024,aes128-sha1-modp1024,aes256-sha384-modp1536,aes256-sha256-modp1536,aes256-sha1-modp1536,aes256-sha384-modp1024,aes256-sha256-modp1024,aes256-sha1-modp1024,aes128gcm16,aes256gcm16,aes128-sha256,aes128-sha1,aes256-sha384,aes256-sha256,aes256-sha1!
dpdaction=clear
dpddelay=300s
rekey=yes
left=%any
# I only want to tunnel Google sites. So, the list are some of Google's subnet
leftsubnet=208.64.38.55/32,66.7.213.62/32,66.171.248.172/32,64.233.160.0/19,64.102.0.0/20,64.249.64.0/19,72.14.192.0/18,74.125.0.0/16,209.85.128.0/17,216.239.32.0/19,173.194.0.0/16
leftcert=caCert.pem
leftfirewall=yes
right=%any
rightdns=8.8.8.8,8.8.4.4
rightsourceip=172.16.16.0/24
conn IPSec-IKEv2
keyexchange=ikev2
auto=add
# Currently used by Windows and Android
conn IKEv2-EAP
also="IPSec-IKEv2"
rightauth=eap-mschapv2
rightsendcert=never
eap_identity=%any
conn IPSec-IKEv1
keyexchange=ikev1
auto=add
# Currently used by OSX and iOS
conn IKEv1-XAUTHPSK
also="IPSec-IKEv1"
xauth=server
authby=xauthpsk
# Optional conn for OSX and iOS
conn CiscoIPSec
also="IPSec-IKEv1"
rightauth=pubkey
rightauth2=xauth
The unity plugin is enabled in strongswan.conf
charon {
load_modular = yes
plugins {
include strongswan.d/charon/*.conf
}
cisco_unity = yes
}
include strongswan.d/*.conf
ipsec statusall result:
Status of IKE charon daemon (strongSwan 5.1.2, Linux 3.13.0-32-generic, x86_64): uptime: 5 seconds, since Oct 16 01:22:04 2014 malloc: sbrk 1617920, mmap 0, used 564480, free 1053440 worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, scheduled: 0 loaded plugins: charon test-vectors sqlite aes rc2 sha1 sha2 md4 md5 rdrand random nonce x509 revocation constraints pkcs1 pkcs7 pkcs8 pkcs12 pem openssl fips-prf xcbc cmac hmac ctr ccm gcm attr kernel-netlink resolve socket-default stroke 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-noauth tnc-tnccs tnccs-20 tnccs-11 tnccs-dynamic dhcp lookip error-notify led addrblock unity Virtual IP pools (size/online/offline): 172.16.16.0/24: 254/0/0 Listening IP addresses: 104.131.111.153 Connections: IPSec-IKEv2: %any...%any IKEv2, dpddelay=300s IPSec-IKEv2: local: [C=US, O=strongSwan, CN=104.131.111.153] uses public key authentication IPSec-IKEv2: cert: "C=US, O=strongSwan, CN=104.131.111.153" IPSec-IKEv2: remote: uses public key authentication IPSec-IKEv2: child: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 === dynamic TUNNEL, dpdaction=clear IKEv2-EAP: %any...%any IKEv2, dpddelay=300s IKEv2-EAP: local: [C=US, O=strongSwan, CN=104.131.111.153] uses public key authentication IKEv2-EAP: cert: "C=US, O=strongSwan, CN=104.131.111.153" IKEv2-EAP: remote: uses EAP_MSCHAPV2 authentication with EAP identity '%any' IKEv2-EAP: child: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 === dynamic TUNNEL, dpdaction=clear IPSec-IKEv1: %any...%any IKEv1, dpddelay=300s IPSec-IKEv1: local: [C=US, O=strongSwan, CN=104.131.111.153] uses public key authentication IPSec-IKEv1: cert: "C=US, O=strongSwan, CN=104.131.111.153" IPSec-IKEv1: remote: uses public key authentication IPSec-IKEv1: child: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 === dynamic TUNNEL, dpdaction=clear IKEv1-XAUTHPSK: %any...%any IKEv1, dpddelay=300s IKEv1-XAUTHPSK: local: [C=US, O=strongSwan, CN=104.131.111.153] uses pre-shared key authentication IKEv1-XAUTHPSK: cert: "C=US, O=strongSwan, CN=104.131.111.153" IKEv1-XAUTHPSK: remote: uses pre-shared key authentication IKEv1-XAUTHPSK: remote: uses XAuth authentication: any IKEv1-XAUTHPSK: child: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 === dynamic TUNNEL, dpdaction=clear CiscoIPSec: %any...%any IKEv1, dpddelay=300s CiscoIPSec: local: [C=US, O=strongSwan, CN=104.131.111.153] uses public key authentication CiscoIPSec: cert: "C=US, O=strongSwan, CN=104.131.111.153" CiscoIPSec: remote: uses public key authentication CiscoIPSec: remote: uses XAuth authentication: any CiscoIPSec: child: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 === dynamic TUNNEL, dpdaction=clear Security Associations (0 up, 0 connecting): none
And here's my firewall rules:
nat
Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain INPUT (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination SNAT !esp -- anywhere anywhere to:104.131.111.153 ACCEPT all -- 172.16.16.0/24 anywhere policy match dir out pol ipsec MASQUERADE all -- 172.16.16.0/24 anywhere
filter
Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- anywhere anywhere udp dpt:isakmp ACCEPT udp -- anywhere anywhere udp dpt:ipsec-nat-t ACCEPT esp -- anywhere anywhere Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination ACCEPT esp -- anywhere anywhere
Also, one weird thing in iOS split tunneling is it tunnels only the first subnet assigned in the leftsubnet, but others following it does not.
Am I missing something here? Do you have any ideas why this issues are occurring when I try to enable the split tunneling?
I had attached some log files for each platform when I tried to connect to them.
I hope all the details I had provided will help solving this issue.
Looking forward for your reply.
My Best,
Eric
Associated revisions
History
#1 Updated by Tobias Brunner almost 6 years ago
- Tracker changed from Issue to Bug
- Status changed from New to Feedback
- Priority changed from High to Normal
- In Windows, I can connect to the VPN but can't browse the internet.
Windows 7 supports split tunneling only in very specific circumstances. Please have a look at ForwardingAndSplitTunneling.
- In iOS, I can connect to the VPN and can also browse the web but not the sites included in the leftsubnet.
... Oct 16 01:59:41 server charon: 16[CFG] sending UNITY_SPLIT_INCLUDE: 208.64.38.55/32 66.7.213.62/32 66.171.248.172/32 64.233.160.0/19 64.102.0.0/20 64.249.64.0/19 72.14.192.0/18 74.125.0.0/16 209.85.128.0/17 216.239.32.0/19 173.194.0.0/16 ... Oct 16 01:59:42 server charon: 04[CFG] selecting traffic selectors for us: Oct 16 01:59:42 server charon: 04[CFG] config: 208.64.38.55/32, received: 208.64.38.55/32 => match: 208.64.38.55/32 Oct 16 01:59:42 server charon: 04[CFG] config: 66.7.213.62/32, received: 208.64.38.55/32 => no match ...
While a list of all subnets is sent in a Unity Split-Include payload (courtesy of the unity plugin), the iOS client seems to return the first one instead of proposing 0.0.0.0/0 in its Quick Mode request. Interestingly though, it then continues to initiate Quick Mode exchanges, apparently for each individual remote subnet. That's not really how strongSwan expects Cisco Unity to work, it expects a single Quick Mode exchange with a remote subnet of 0.0.0.0/0 (but since Unity is not standardized or even documented...).
Which version of iOS do you use? If you use iOS 8 (and the upcoming Mac OS X Yosemite) you might want to consider using IKEv2, see AppleIKEv2Profile.
- In OSX, VPN connection is established but destroyed immediately.
Like the iOS client it sends the first subnet instead of 0.0.0.0/0 during Quick Mode. But then it sends back an ATTRIBUTES_NOT_SUPPORTED notify and deletes the IKE_SA. Could be because strongSwan returns 0.0.0.0/0 as its traffic selector since 5.1.2.
I actually did some tests now with iOS 8, and I see it return ATTRIBUTES_NOT_SUPPORTED like Mac OS X did in your tests. As far as I could determine it is, in fact, caused by f8262aa1a624, which is required for interoperability with Shrew and the original Cisco client (and maybe others). If you don't have any such clients you may revert that commit to fix the issue.
Otherwise, it looks like we have to return the original traffic selector the client proposed (the first subnet for iOS/Mac, and 0.0.0.0/0 for the others). Unfortunately, we don't have that information available when we narrow/modify the traffic selector in the unity plugin. In the unity-ios branch I've implemented a workaround though. It's kind of a hack, but it works fine for iOS 8, Shrew and the Cisco client in my tests.
#2 Updated by Alexander Kalashnikov almost 6 years ago
Hello,
Cisco devices are using 0.0.0.0/0 TS for one shared SA negotiation, when Unity is used.
The list of IPs placed in Unity payloads are used for routing purpose only.
ShrewSoft VPN has option to use such configuration. Actually it is so by default [1].
Whoever Blackberry or Cisco VPN client has not such option, so it fails to negotiate phase 2 because of invalid configuration.
So, it seems like you should consider refactoring of overall logic. Like split TS for SA and TS in Cisco Unity by adding some additional left(right)subnet parameter for this separate entities.
___________________________________________________________________
[1] https://www.shrew.net/static/help-2.1.x/vpnhelp.htm?PolicySettings.html
#3 Updated by Tobias Brunner almost 6 years ago
Whoever Blackberry or Cisco VPN client has not such option, so it fails to negotiate phase 2 because of invalid configuration.
I tested with the Cisco client (and Shrew and iOS 8) and it worked fine. I've no Blackberry so I can't test that. But as far as I know Blackberries support IKEv2, so this is not really an issue. Did you try the code in the unity-ios branch?
So, it seems like you should consider refactoring of overall logic. Like split TS for SA and TS in Cisco Unity by adding some additional left(right)subnet parameter for this separate entities.
Yes, a unity plugin specific option to define these subnets, while configuring leftsubnet=0.0.0.0/0 would probably help, but until it's easy to define such options in ipsec.conf/swanctl.conf this won't happen.
#4 Updated by Tobias Brunner over 5 years ago
- Status changed from Feedback to Closed
- Target version set to 5.2.2
- Resolution set to Fixed
I did some additional tests (with actual traffic to different subnets). It seems that iOS does negotiate separate IPsec SAs for each subnet passed via Unity. And at least iOS 8.1.1 does so only based on traffic, only the first IPsec SA is established automatically. Therefore, similar to the traffic selector returned to the client, the unity plugin should only replace the TS to be installed if the client proposed 0.0.0.0/0 and otherwise just accept the client's proposal of one of these subnets.
The associated commit does so.
#5 Updated by Len Relsson over 5 years ago
This patch from revision 02df52fd fixes MacOSX client but it breaks native Cisco VPN client.
It can be reproduced easily every time.
I have applied only this single patch to strongswan-5.2.1.
After applying the patch, I can't connect anymore using Cisco VPN client, neither when using the same strongSwan as a client.
After successful authentication (RSA+XAUTH) and after sending two subnets (UNITY_SPLIT_INCLUDE) I'm getting this error on server side every time:
Dec 26 01:36:53 vpnserver charon: 13[IKE] no matching CHILD_SA config found Dec 26 01:36:53 vpnserver charon: 13[ENC] generating INFORMATIONAL_V1 request 942675489 [ HASH N(INVAL_ID) ] Dec 26 01:36:53 vpnserver charon: 13[NET] sending packet: from *ipserver*[500] to *ipremote*[500] (76 bytes)
After removing the patch Cisco VPN Client and strongSwan as a client work like before.
#6 Updated by Alexander Ostapchuk over 5 years ago
I was build ver 5.2.2rc1 and Cisco VPN client work as expected.
This patch also req this patch https://git.strongswan.org/?p=strongswan.git;a=commit;h=bf5d0693efe8aca8c1b87457ed2da322d72a23fa and may be more.
Len Relsson wrote:
This patch from revision 02df52fd fixes MacOSX client but it breaks native Cisco VPN client.
It can be reproduced easily every time.
I have applied only this single patch to strongswan-5.2.1.
#7 Updated by Len Relsson over 5 years ago
Alexander Ostapchuk wrote:
I was build ver 5.2.2rc1 and Cisco VPN client work as expected.
I can confirm that 5.2.2rc1 works with Cisco VPN client. Thanks.
Still I can't get Shrew client to work with 5.2.2rc1.
I'm getting the same message as before:
no matching CHILD_SA config found
unity: Only do narrowing of responder's TS if we received 0.0.0.0/0
iOS and Mac OS X clients establish individual IPsec SAs for the traffic
selectors received in Split-Include attributes (might have been different
in earlier releases). If we return 0.0.0.0/0 as TSr that either results
in a bunch of Quick Mode exchanges (for each TS), or with the latest
client releases an error notify (ATTRIBUTES_NOT_SUPPORTED).
We also can't install the IPsec SA with all configured subnets as that
would cause conflicts if the client later negotiates SAs for other subnets,
which iOS 8 does based on traffic to such subnets.
For Shrew and the Cisco client, which propose 0.0.0.0/0, we still need to
override the narrowed TS with 0.0.0.0/0, as they otherwise won't accept
the Quick Mode response. Likewise, we also have to narrow the TS before
installing the IPsec SAs and policies.
So we basically have to follow the client's proposal and only modify TSr
if we received 0.0.0.0/0. Since we don't get the original TS in the
narrow hook we handle the inbound QM messages and make note of IKE_SAs on
which we received a TSr of 0.0.0.0/0.
Fixes #737.