[strongSwan] Exclude protocol from IPsec

agarwalpiyush at gmail.com agarwalpiyush at gmail.com
Tue May 23 23:48:34 CEST 2017


Hi,
Thanks for the suggestion. With the change you recommended, I do see some 
progress. But here are the issues:

1) client -> server ping: I do see echo request is un-encrypted as seen by 
tcpdump on server's interface. But tcpdump on the server's interface shows 
no reply being generated (if I remove passthrough policy, the encrypted 
replies work just fine). I saw threads about strongswan using route table 
220, but I don't see any output of "ip route show table 220". Why is 
"auto=route" required? How is it messing with the server side's echo reply, 
assuming that is the case? I tried with auto=start but that still had ICMP 
packets encrypted.

2) server -> client ping: I see server's ping show up encrypted on the 
client's interface. Client's interface tcpdump sees un-unencrypted echo 
reply. But this reply is not seen on server's interface at all!!

Does the order of IP addresses in output of "Shunted policies" have any 
significance? I see server side is showing shunted connected as "client/32 
== server/32" which is not what I expected.

*Client output:*
*client$:ipsec status*
Shunted Connections:
*        skip:  1.100.0.9/32[icmp] === 1.100.0.5/32[icmp] PASS*
Security Associations (1 up, 0 connecting):
   1.100.0.5[1]: ESTABLISHED 8 minutes ago, 1.100.0.9[C=US, ST=CA, 
L=Mountain View, O=OWCA, OU=AgentC, CN=owca.com]...1.100.0.5[C=US, ST=CA, 
L=Mountain View, O=OWCA, OU=AgentC, CN=owca.com]
   1.100.0.5{1}:  INSTALLED, TRANSPORT, reqid 1, ESP SPIs: c5067855_i 
cfc50c8b_o
   1.100.0.5{1}:   1.100.0.9/32 === 1.100.0.5/32

*Server output:*
*server$:ipsec status*
Shunted Connections:
*        skip:  1.100.0.9/32[icmp] === 1.100.0.5/32[icmp] PASS*
Security Associations (1 up, 0 connecting):
   1.100.0.9[1]: ESTABLISHED 9 minutes ago, 1.100.0.5[C=US, ST=CA, 
L=Mountain View, O=OWCA, OU=AgentC, CN=owca.com]...1.100.0.9[C=US, ST=CA, 
L=Mountain View, O=OWCA, OU=AgentC, CN=owca.com]
   1.100.0.9{1}:  INSTALLED, TRANSPORT, reqid 1, ESP SPIs: cfc50c8b_i 
c5067855_o
   1.100.0.9{1}:   1.100.0.5/32 === 1.100.0.9/32

Much appreciate any help. Racoon/setkey was very straightforward to get 
this working :( Hopefully it is a mistake I am making/misconfiguring etc.

Reprinting the ipsec.conf (after changes were done):
*Client:*

conn skip
    type=passthrough
    left=127.0.0.1
    leftsubnet=1.100.0.9/32[icmp/]
    leftcert=client_cert.pem
    leftsendcert=always
    rightcert=server_cert.pem
    right=127.0.0.1
    rightsubnet=1.100.0.5/32[icmp/]
    auto=route

conn 1.100.0.5
    type=transport
    left=1.100.0.9
    leftcert=client_cert.pem
    leftsendcert=always
    rightcert=server_cert.pem
    right=1.100.0.5
    reauth=no
    dpdaction=restart
    auto=start

*Server:*

conn skip
    type=passthrough
    left=127.0.0.1
    leftsubnet=1.100.0.5/32[icmp/]
    leftcert=server_cert.pem
    leftsendcert=always
    rightcert=client_cert.pem
    right=127.0.0.1
    rightsubnet=1.100.0.9/32[icmp/]
    auto=route

conn 1.100.0.9
    type=transport
    left=1.100.0.5
    leftcert=server_cert.pem
    leftsendcert=always
    rightcert=client_cert.pem
    right=1.100.0.9
    reauth=no
    dpdaction=restart
    auto=add


Thanks!

On Tuesday, May 23, 2017 at 12:30:15 PM UTC-7, Dusan Ilic wrote:
>
> Try following
>
>     type=passthrough
>     left=127.0.0.1
>     leftsubnet=1.100.0.9/32[icmp/]
>     right=127.0.0.1
>     rightsubnet=1.100.0.5/32[icmp/]
>     auto=route
>
>
>
> ---- agarwa... at gmail.com <javascript:> skrev ----
>
> Reading another thread, I changed "right" of "skip" connection on both 
> client and server to be  "127.0.0.1" and that fixed up a few things:
> 1) The IPsec installed is type transport (as desired)
> 2) I do see shunted policies list ICMP PASS
>
> *However, I still have my pings from client to server encrypted :(*
>
> *Client:*
> # ipsec statusall
> Status of IKE charon daemon (strongSwan 5.1.2, Linux 4.4.0-75-generic, 
> x86_64):
>   uptime: 10 minutes, since May 23 12:02:46 2017
>   malloc: sbrk 2564096, mmap 0, used 393728, free 2170368
>   worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, 
> scheduled: 3
>   loaded plugins: charon test-vectors aes rc2 sha1 sha2 md4 md5 rdrand 
> random nonce x509 revocation constraints pkcs1 pkcs7 pkcs8 pkcs12 pem 
> openssl xcbc cmac hmac ctr ccm gcm attr kernel-netlink resolve 
> socket-default stroke updown eap-identity addrblock
> Listening IP addresses:
>   1.100.0.9
> Connections:
>         skip:  %any...127.0.0.1  IKEv2
>         skip:   local:  [C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com] uses public key authentication
>         skip:    cert:  "C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com"
>         skip:   remote: [C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com] uses public key authentication
>         skip:    cert:  "C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com"
>         skip:   child:  0.0.0.0/0[icmp] === 0.0.0.0/0[icmp] PASS
>    1.100.0.5:  1.100.0.9...1.100.0.5  IKEv2, dpddelay=60s
>    1.100.0.5:   local:  [C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com] uses public key authentication
>    1.100.0.5:    cert:  "C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com"
>    1.100.0.5:   remote: [C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com] uses public key authentication
>    1.100.0.5:    cert:  "C=US, ST=CA, L=Mountain View, O=TEST, OU=AgentC, 
> CN=test.com"
>    1.100.0.5:   child:  dynamic === dynamic *TRANSPORT*, dpdaction=restart
> *Shunted Connections:*
> *        skip:  0.0.0.0/0[icmp] === 0.0.0.0/0[icmp] PASS*
> Security Associations (1 up, 0 connecting):
>    1.100.0.5[1]: ESTABLISHED 10 minutes ago, 1.100.0.9[C=US, ST=CA, 
> L=Mountain View, O=TEST, OU=AgentC, CN=test.com]...1.100.0.5[C=US, ST=CA, 
> L=Mountain View, O=TEST, OU=AgentC, CN=test.com]
>    1.100.0.5[1]: IKEv2 SPIs: be5caa6cea2281c2_i* 79bb5ad924d8d919_r, 
> rekeying in 44 minutes
>    1.100.0.5[1]: IKE proposal: 
> AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_2048
>    1.100.0.5{1}:  INSTALLED, *TRANSPORT*, ESP SPIs: c989f733_i c3f6a42e_o
>    1.100.0.5{1}:  AES_CBC_128/HMAC_SHA1_96, 520206 bytes_i (2551 pkts, 1s 
> ago), 1691623 bytes_o (2986 pkts, 10s ago), rekeying in 5 minutes
>    1.100.0.5{1}:   *1.100.0.9/32 === 1.100.0.5/32* 
>
>
> *Client setkey -DP output:*
> 1.100.0.5[any] 1.100.0.9[any] 255
>         in prio high + 1073740029 ipsec
>         esp/transport//unique:1
>         created: May 23 12:18:12 2017  lastused: May 23 12:18:52 2017
>         lifetime: 0(s) validtime: 0(s)
>         spid=2248 seq=1 pid=176401
>         refcnt=11
> 1.100.0.9[any] 1.100.0.5[any] 255
>         out prio high + 1073740029 ipsec
>         esp/transport//unique:1
>         created: May 23 12:18:12 2017  lastused: May 23 12:18:47 2017
>         lifetime: 0(s) validtime: 0(s)
>         spid=2241 seq=2 pid=176401
>         refcnt=11
> 0.0.0.0/0 0.0.0.0/0 icmp
>         fwd prio high + 1073739774 none
>         created: May 23 12:02:46 2017  lastused:                     
>         lifetime: 0(s) validtime: 0(s)
>         spid=2130 seq=3 pid=176401
>         refcnt=1
> 0.0.0.0/0 0.0.0.0/0 icmp
>         in prio high + 1073739774 none
>         created: May 23 12:02:46 2017  lastused: May 23 12:02:50 2017
>         lifetime: 0(s) validtime: 0(s)
>         spid=2120 seq=4 pid=176401
>         refcnt=1
> 0.0.0.0/0 0.0.0.0/0 icmp
>         out prio high + 1073739774 none
>         created: May 23 12:02:46 2017  lastused:                     
>         lifetime: 0(s) validtime: 0(s)
>         spid=2113 seq=5 pid=176401
>         refcnt=1
>
>
> On Tuesday, May 23, 2017 at 11:29:04 AM UTC-7, agarwa... at gmail.com wrote:
>>
>> Hi Noel,
>> Many thanks for the pointer. Looks like I am missing something more or 
>> perhaps making a mistake. 
>>
>> Client [1.100.0.9] -- Server [1.100.0.5] 
>>
>> Goal: All non-ICMP traffic to be over IPsec tunnel between these two 
>> machines.
>>
>> Strongswan 5.1.2
>>
>> The client and server are using self-signed certificates and have each 
>> other's certs in /etc/ipsec.d/certs/
>>
>> *Client ipsec.conf <http://ipsec.conf>:*
>>
>> config setup
>>     charondebug = "dmn 0,mgr 1, ike 2, job 2, cfg 2, knl 1, net 1, tls 1, 
>> lib 0, enc 0, tnc 0"
>>     uniqueids=no
>>
>> conn %default
>>     ikelifetime=60m
>>     keylife=20m
>>     rekeymargin=3m
>>     keyingtries=1
>>     keyexchange=ikev2
>>     authby=rsasig
>>
>> conn skip
>>     type=*passthrough*
>>     left=1.100.0.9
>>     leftsubnet=0.0.0.0/0[icmp/] <http://0.0.0.0/0%5Bicmp/%5D>
>>     leftcert=client_cert.pem
>>     leftsendcert=always
>>     rightcert=server_cert.pem
>>     right=1.100.0.5
>>     rightsubnet=0.0.0.0/0[icmp/] <http://0.0.0.0/0%5Bicmp/%5D>
>>     auto=route
>>
>> conn 1.100.0.5
>>     type=*transport*
>>     left=1.100.0.9
>>     leftcert=client_cert.pem
>>     leftsendcert=always
>>     rightcert=server_cert.pem
>>     right=1.100.0.5
>>     reauth=no
>>     auto=start
>>
>> *Server ipsec.conf <http://ipsec.conf>:*
>>
>> config setup
>>     charondebug = "dmn 0,mgr 1, ike 2, job 2, cfg 2, knl 1, net 1, tls 1, 
>> lib 0, enc 0, tnc 0"
>>     uniqueids=no
>>
>> conn %default
>>     ikelifetime=60m
>>     keylife=20m
>>     rekeymargin=3m
>>     keyingtries=1
>>     keyexchange=ikev2
>>     authby=rsasig
>>
>> conn skip
>>     type=*passthrough*
>>     left=1.100.0.5
>>     leftsubnet=0.0.0.0/0[icmp/] <http://0.0.0.0/0%5Bicmp/%5D>
>>     leftcert=server_cert.pem
>>     leftsendcert=always
>>     rightcert=client_cert.pem
>>     right=1.100.0.9
>>     rightsubnet=0.0.0.0/0[icmp/] <http://0.0.0.0/0%5Bicmp/%5D>
>>     auto=route
>>
>> conn 1.100.0.9
>>     type=*transport*
>>     left=1.100.0.5
>>     leftcert=server_cert.pem
>>     leftsendcert=always
>>     rightcert=client_cert.pem
>>     right=1.100.0.9
>>     reauth=no
>>     auto=add
>>
>> =============
>> Output of setkey -DP on client:
>> root at agarwalpiyush0:/usr/local/google/home/agarwalpiyush/work/agent-v# 
>> ./sbin/nfv_cli dm_carl0 setkey -DP
>> 1.100.0.5 1.100.0.9 icmp
>>         fwd prio high + 1073740030 ipsec
>>         esp/tunnel/1.100.0.5-1.100.0.9/unique:1
>>         created: May 23 11:21:42 2017  lastused:                     
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1834 seq=1 pid=103981
>>         refcnt=1
>> 1.100.0.5 1.100.0.9 icmp
>>         in prio high + 1073740030 ipsec
>>         esp/tunnel/1.100.0.5-1.100.0.9/unique:1
>>         created: May 23 11:21:42 2017  lastused:                     
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1824 seq=2 pid=103981
>>         refcnt=1
>> 1.100.0.9 1.100.0.5 icmp
>>         out prio high + 1073740030 ipsec
>>         esp/tunnel/1.100.0.9-1.100.0.5/unique:1
>>         created: May 23 11:21:42 2017  lastused:                     
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1817 seq=3 pid=103981
>>         refcnt=1
>> 0.0.0.0/0 0.0.0.0/0 icmp
>>         fwd prio high + 1073739774 none
>>         created: May 23 11:21:31 2017  lastused:                     
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1698 seq=4 pid=103981
>>         refcnt=1
>> 0.0.0.0/0 0.0.0.0/0 icmp
>>         in prio high + 1073739774 none
>>         created: May 23 11:21:31 2017  lastused: May 23 11:21:35 2017
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1688 seq=5 pid=103981
>>         refcnt=2
>> 0.0.0.0/0 0.0.0.0/0 icmp
>>         out prio high + 1073739774 none
>>         created: May 23 11:21:31 2017  lastused:                     
>>         lifetime: 0(s) validtime: 0(s)
>>         spid=1681 seq=6 pid=103981
>>         refcnt=1
>>
>>
>> Questions:
>> 1) I'd like a transport type IPsec session for all non-ICMP traffic 
>> between client and server. As soon as I specify "passthrough" policy, my 
>> IPsec session changes to type "tunnel" from output of ipsec status. Clearly 
>> I am not specifying passthrough policy correctly.
>>
>> 1) Do I need to specify left/right for my "skip" passthrough conn? If I 
>> do NOT specify left and right for skip connection, I see the IPsec type 
>> remains transport (which is good and what I want), I do see shunted 
>> policies in "ipsec status" but I still see ping packets are encrypted.
>>
>> Thank you for any help!
>> Piyush
>>
>> On Monday, May 22, 2017 at 12:19:17 PM UTC-7, Noel Kuntze wrote:
>>>
>>> Add a passthrough policy for the protocol.
>>>
>>> Am 22. Mai 2017 19:09:03 MESZ schrieb Piyush Agarwal <
>>> agarwa... at gmail.com>:
>>>>
>>>> Hi,
>>>> Reading through the left|rightsubnet, it seems like there is no way to 
>>>> *exclude* a protocol from getting encrypted? 
>>>>
>>>> I have a host to host tunnel and I want to encrypt everything between 
>>>> these except ICMP since I'd like to do out-of-tunnel ping/traceroute.
>>>>
>>>> Prior to using strongswan, I was using racoon where I could use setkey 
>>>> to manually update the SPD to exclude icmp alone.
>>>>
>>>> Please advise if there is any way to achieve this with strongswan.
>>>>
>>>> Thanks.
>>>>
>>>> -- 
>>>> Piyush Agarwal
>>>> Life can only be understood backwards; but it must be lived forwards.
>>>>
>>>
>>> -- 
>>> Sent from mobile
>>>
>>
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