3 \label{section:IPSECgeneral}
5 % ciphersuites current 2013-12-09
8 \item[Settings:] \mbox{}
10 \paragraph*{Assumptions}\mbox{}\\
12 We assume the use of IKE (v1 or v2) and ESP for this document.
14 \paragraph*{Authentication}\mbox{}\\
16 IPSEC authentication should optimally be performed via RSA signatures,
17 with a key size of 2048 bits or more. Configuring only the trusted CA
18 that issued the peer certificate provides for additional protection
19 against fake certificates.
21 If you need to use Pre-Shared Key authentication:
24 \item Choose a \textbf{random}, \textbf{long enough} PSK (see below)
25 \item Use a \textbf{separate} PSK for any IPSEC connection
26 \item Change the PSKs regularily
29 The size of the PSK should not be shorter than the output size of
30 the hash algorithm used in IKE \footnote{It is used in a HMAC, see
31 RFC2104\cite{rfc2104} and the discussion starting
32 in \url{http://www.vpnc.org/ietf-ipsec/02.ipsec/msg00268.html}.}.
34 For a key composed of upper- and lowercase letters, numbers, and two
35 additional symbols\footnote{64 possible values = 6 bits},
36 table~\ref{tab:IPSEC_psk_len} gives the minimum lengths in characters.
43 IKE Hash & PSK length \\
51 \label{tab:IPSEC_psk_len}
54 \paragraph*{Cryptographic Suites}\mbox{}\\
56 IPSEC Cryptographic Suites are pre-defined settings for all the items
57 of a configuration; they try to provide a balanced security level and
58 make setting up VPNs easier.
59 \footnote{RFC6379\cite{rfc6379}, RFC4308\cite{rfc4308}}
61 When using any of those suites, make sure to enable ``Perfect Forward
62 Secrecy`` for Phase 2, as this is not specified in the suites. The
63 equivalents to the recommended ciphers suites in section
64 \ref{section:recommendedciphers} are shown in
65 table~\ref{tab:IPSEC_suites}.
70 \begin{tabular}{p{2.5cm}p{2.5cm}l}
72 Configuration A & Configuration B & Notes\\
74 \verb|Suite-B-GCM-256| &
75 \verb|Suite-B-GCM-128| \newline
77 & All Suite-B variants use NIST elliptic curves\\
80 \caption{IPSEC Cryptographic Suites}
81 \label{tab:IPSEC_suites}
84 \paragraph*{IKE or Phase 1}\mbox{}\\
86 Alternatively to the pre-defined cipher suites, you can define your
87 own, as described in this and the next section.
89 IKE or Phase 1 is the mutual authentication and key exchange phase;
90 table~\ref{tab:IPSEC_ph1_params} shows the parameters.
92 Use only ``main mode``, as ``aggressive mode`` has known security
93 vulnerabilities \footnote{\url{http://ikecrack.sourceforge.net/}}.
100 & Configuration A & Configuration B \\
102 Mode & Main Mode & Main Mode \\
103 Encryption & AES-256 & AES, CAMELLIA (-256 or -128) \\
104 Hash & SHA2-* & SHA2-*, SHA1 \\
105 DH Group & Group 14, 18 & Group 14, 18 \\
106 % Lifetime & \todo{need recommendations; 1 day seems to be common
110 \caption{IPSEC Phase 1 parameters}
111 \label{tab:IPSEC_ph1_params}
114 \paragraph*{ESP or Phase 2}\mbox{}\\
116 ESP or Phase 2 is where the actual data are protected; recommended
117 parameters are shown in table \ref{tab:IPSEC_ph2_params}.
124 & Configuration A & Configuration B \\
126 Perfect Forward Secrecy & yes & yes \\
128 \parbox[t]{5cm}{\raggedright
129 \mbox{AES-GCM-16}, \mbox{AES-CTR}, \mbox{AES-CCM-16}, \mbox{AES-256}}
131 \parbox[t]{5cm}{\raggedright
132 \mbox{AES-GCM-16}, \mbox{AES-CTR}, \mbox{AES-CCM-16}, \mbox{AES-256}, \mbox{CAMELLIA-256}, \mbox{AES-128}, \mbox{CAMELLIA-128}} \\
133 Hash & SHA2-* (or none for AEAD) & SHA2-*, SHA1 (or none for AEAD) \\
134 DH Group & Same as Phase 1 & Same as Phase 1 \\
135 % Lifetime & \todo{need recommendations; 1-8 hours is common} & \\
138 \caption{IPSEC Phase 2 parameters}
139 \label{tab:IPSEC_ph2_params}
142 \item[References:] \mbox{}
144 ``A Cryptographic Evaluation of IPsec'', Niels Ferguson and Bruce
145 Schneier: \url{https://www.schneier.com/paper-ipsec.pdf}
149 \subsubsection{Check Point FireWall-1}
152 \item[Tested with Version:] \mbox{}
155 \item R77 (should work with any currently supported version)
158 \item[Settings:] \mbox{}
160 Please see section \ref{section:IPSECgeneral} for guidance on
161 parameter choice. In this section, we will configure a strong setup
162 according to ``Configuration A''.
164 This is based on the concept of a ``VPN Community'', which has all the
165 settings for the gateways that are included in that community.
166 Communities can be found in the ``IPSEC VPN'' tab of SmartDashboard.
170 \includegraphics[width=0.592\textwidth]{checkpoint_1.png}
171 \caption{VPN Community encryption properties}
172 \label{fig:checkpoint_1}
175 Either chose one of the encryption suites in the properties dialog
176 (figure \ref{fig:checkpoint_1}), or proceed to
177 ``Custom Encryption...'', where you can set encryption and hash for
178 Phase 1 and 2 (figure \ref{fig:checkpoint_2}).
182 \includegraphics[width=0.411\textwidth]{checkpoint_2.png}
183 \caption{Custom Encryption Suite Properties}
184 \label{fig:checkpoint_2}
187 The Diffie-Hellman groups and Perfect Forward Secrecy Settings can be
188 found under ``Advanced Settings'' / ``Advanced VPN Properties''
189 (figure \ref{fig:checkpoint_3}).
193 \includegraphics[width=0.589\textwidth]{checkpoint_3.png}
194 \caption{Advanced VPN Properties}
195 \label{fig:checkpoint_3}
198 \item[Additional settings:] \mbox{}
200 For remote Dynamic IP Gateways, the settings are not taken from the
201 community, but set in the ``Global Properties'' dialog under ``Remote
202 Access'' / ``VPN Authentication and Encryption''. Via the ``Edit...''
203 button, you can configure sets of algorithms that all gateways support
204 (figure \ref{fig:checkpoint_4}).
208 \includegraphics[width=0.474\textwidth]{checkpoint_4.png}
209 \caption{Remote Access Encryption Properties}
210 \label{fig:checkpoint_4}
213 Please note that these settings restrict the available algorithms for
214 \textbf{all} gateways, and also influence the VPN client connections.
216 %\item[Justification for special settings (if needed):]
220 \item[References:]\mbox{}
225 \href{https://sc1.checkpoint.com/documents/R77/CP_R77_VPN_AdminGuide/html_frameset.htm}{VPN
226 R77 Administration Guide} (may require a
227 UserCenter account to access)
231 % \item[How to test:]
236 %% cipherstrings current 2013-12-09
237 \subsubsection{OpenVPN}
241 \item[Tested with Version:] \mbox{}\\
244 \item OpenVPN 2.3.2 from Debian ``wheezy-backports'' linked against openssl (libssl.so.1.0.0)
245 \item OpenVPN 2.2.1 from Debian 7.0 linked against openssl
247 \item OpenVPN 2.3.2 for Windows
250 \item[Settings:] \mbox{}
252 \paragraph{General}\mbox{}
254 We describe a configuration with certificate-based authentication; see
255 below for details on the \verb|easyrsa| tool to help you with that.
257 OpenVPN uses TLS only for authentication and key exchange. The
258 bulk traffic is then encrypted and authenticated with the OpenVPN
259 protocol using those keys.
261 Note that while the \verb|tls-cipher| option takes a list of ciphers
262 that is then negotiated as usual with TLS, the \verb|cipher|
263 and \verb|auth| options both take a single argument that must match on
266 \paragraph{Server Configuration}\mbox{}
268 % this is only a DoS-protection, out of scope:
269 % # TLS Authentication
274 % ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-SHA256:DHE-RSA-CAMELLIA256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES256-SHA:AES256-SHA
275 % the cipherlist here is config B without the ECDHE strings, because
276 % it must fit in 256 bytes...
277 \begin{lstlisting}[breaklines]
278 tls-cipher DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-CAMELLIA256-SHA:DHE-RSA-AES256-SHA:DHE-RSA-CAMELLIA128-SHA:DHE-RSA-AES128-SHA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA
283 \paragraph{Client Configuration}\mbox{}
285 Client and server have to use compatible configurations, otherwise they can't communicate.
286 The \verb|cipher| and \verb|auth| directives have to be identical.
288 \begin{lstlisting}[breaklines]
289 tls-cipher DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-CAMELLIA256-SHA:DHE-RSA-AES256-SHA:DHE-RSA-CAMELLIA128-SHA:DHE-RSA-AES128-SHA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA
293 # http://openvpn.net/index.php/open-source/documentation/howto.html#mitm
294 remote-cert-tls server
296 tls-remote server.example.com
299 \item[Justification for special settings (if needed):] \mbox{}\\
301 OpenVPN 2.3.1 changed the values that the \verb|tls-cipher| option
302 expects from OpenSSL to IANA cipher names. That means from that
303 version on you will get ``Deprecated TLS cipher name'' warnings for
304 the configurations above. You cannot use the selection strings from
305 section \ref{section:recommendedciphers} directly from 2.3.1 on, which
306 is why we give an explicit cipher list here.
308 In addition, there is a 256 character limit on configuration file line
309 lengths; that limits the size of cipher suites, so we dropped all
312 The configuration shown above is compatible with all tested versions.
314 \item[References:] \mbox{}\\
316 \url{http://openvpn.net/index.php/open-source/documentation/security-overview.html}
321 \item[Additional settings:] \mbox{}
323 \paragraph{Key renegotiation interval}\mbox{}
325 The default for renegotiation of encryption keys is one hour
326 (\verb|reneg-sec 3600|). If you
327 transfer huge amounts of data over your tunnel, you might consider
328 configuring a shorter interval, or switch to a byte- or packet-based
329 interval (\verb|reneg-bytes| or \verb|reneg-pkts|).
331 \paragraph{Fixing ``easy-rsa''}\mbox{}
333 When installing an OpenVPN server instance, you are probably using
334 {\it easy-rsa} to generate keys and certificates.
335 The file \verb|vars| in the easyrsa installation directory has a
336 number of settings that should be changed to secure values:
338 \begin{lstlisting}[breaklines]
340 export KEY_EXPIRE=365
341 export CA_EXPIRE=1826
344 This will enhance the security of the key generation by using RSA keys
345 with a length of 2048 bits, and set a lifetime of one year for the
346 server/client certificates and five years for the CA certificate.
348 In addition, edit the \verb|pkitool| script and replace all occurences
349 of \verb|sha1| with \verb|sha256|, to sign the certificates with
352 \item[Limitations:] \mbox{}
354 Note that the ciphersuites shown by \verb|openvpn --show-tls| are {\it
355 known}, but not necessarily {\it
356 supported} \footnote{\url{https://community.openvpn.net/openvpn/ticket/304}}.
358 Which cipher suite is actually used can be seen in the logs:
360 \verb|Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-CAMELLIA256-SHA, 2048 bit RSA|
367 PPTP is considered insecure, Microsoft recommends to ``use a more secure VPN
368 tunnel''\footnote{\url{http://technet.microsoft.com/en-us/security/advisory/2743314}}.
370 There is a cloud service that cracks the underlying MS-CHAPv2
371 authentication protocol for the price of USD~200\footnote{\url{https://www.cloudcracker.com/blog/2012/07/29/cracking-ms-chap-v2/}},
372 and given the resulting MD4 hash, all PPTP traffic for a user can
375 \subsubsection{Cisco ASA}
376 The following settings reflect our recommendations as best as possible on the Cisco ASA platform. These are - of course - just settings regarding SSL/TLS (i.e. Cisco AnyConnect) and IPSec. For further security settings regarding this platform the appropriate Cisco guides should be followed.
378 \item[Tested with Version:]
379 9.1(3) - X-series model
380 \item[Settings:] \mbox{}
381 \begin{lstlisting}[breaklines]
382 crypto ipsec ikev2 ipsec-proposal AES-Fallback
383 protocol esp encryption aes-256 aes-192 aes
384 protocol esp integrity sha-512 sha-384 sha-256
385 crypto ipsec ikev2 ipsec-proposal AES-GCM-Fallback
386 protocol esp encryption aes-gcm-256 aes-gcm-192 aes-gcm
387 protocol esp integrity sha-512 sha-384 sha-256
388 crypto ipsec ikev2 ipsec-proposal AES128-GCM
389 protocol esp encryption aes-gcm
390 protocol esp integrity sha-512
391 crypto ipsec ikev2 ipsec-proposal AES192-GCM
392 protocol esp encryption aes-gcm-192
393 protocol esp integrity sha-512
394 crypto ipsec ikev2 ipsec-proposal AES256-GCM
395 protocol esp encryption aes-gcm-256
396 protocol esp integrity sha-512
397 crypto ipsec ikev2 ipsec-proposal AES
398 protocol esp encryption aes
399 protocol esp integrity sha-1 md5
400 crypto ipsec ikev2 ipsec-proposal AES192
401 protocol esp encryption aes-192
402 protocol esp integrity sha-1 md5
403 crypto ipsec ikev2 ipsec-proposal AES256
404 protocol esp encryption aes-256
405 protocol esp integrity sha-1 md5
406 crypto ipsec ikev2 sa-strength-enforcement
407 crypto ipsec security-association pmtu-aging infinite
408 crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set pfs group14
409 crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev2 ipsec-proposal AES256-GCM AES192-GCM AES128-GCM AES-GCM-Fallback AES-Fallback
410 crypto map Outside-DMZ_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP
411 crypto map Outside-DMZ_map interface Outside-DMZ
413 crypto ikev2 policy 1
414 encryption aes-gcm-256
417 prf sha512 sha384 sha256 sha
418 lifetime seconds 86400
419 crypto ikev2 policy 2
420 encryption aes-gcm-256 aes-gcm-192 aes-gcm
423 prf sha512 sha384 sha256 sha
424 lifetime seconds 86400
425 crypto ikev2 policy 3
426 encryption aes-256 aes-192 aes
427 integrity sha512 sha384 sha256
429 prf sha512 sha384 sha256 sha
430 lifetime seconds 86400
431 crypto ikev2 policy 4
432 encryption aes-256 aes-192 aes
433 integrity sha512 sha384 sha256 sha
435 prf sha512 sha384 sha256 sha
436 lifetime seconds 86400
437 crypto ikev2 enable Outside-DMZ client-services port 443
438 crypto ikev2 remote-access trustpoint ASDM_TrustPoint0
440 ssl server-version tlsv1-only
441 ssl client-version tlsv1-only
442 ssl encryption dhe-aes256-sha1 dhe-aes128-sha1 aes256-sha1 aes128-sha1
443 ssl trust-point ASDM_TrustPoint0 Outside-DMZ
446 \item[Justification for special settings (if needed):] \mbox{}
447 New IPsec policies have been defined which do not make use of ciphers that may be cause for concern. Policies have a "Fallback" option to support legacy devices.
449 3DES has been completely disabled as such Windows XP AnyConnect Clients will no longer be able to connect.
451 The Cisco ASA platform does not currently support RSA Keys above 2048bits.
453 Legacy ASA models (e.g. 5505, 5510, 5520, 5540, 5550) do not offer the possibility to configure for SHA256/SHA384/SHA512 nor AES-GCM for IKEv2 proposals.
456 \url{http://www.cisco.com/en/US/docs/security/asa/roadmap/asaroadmap.html}\\
457 \url{http://www.cisco.com/web/about/security/intelligence/nextgen_crypto.html}
459 % add any further references or best practice documents here
461 %%\item[How to test:]
462 % describe here or point the admin to tools (can be a simple footnote or \ref{} to the tools section) which help the admin to test his settings.
472 %%\subsubsection{Juniper VPN}
473 %%\todo{write this subsubsection. AK: ask Hannes}
476 %%\begin{description}
477 %%\item[Tested with Version:] \todo{version?}
479 %%\item[Settings:] \mbox{}
481 %%\begin{lstlisting}[breaklines]
482 %% %Here goes your setting string
485 %%\item[Additional settings:] \mbox{}
487 %Here you can add additional settings
489 %%\begin{lstlisting}[breaklines]
490 %% %copy \& paste additional settings
493 %%\item[Justification for special settings (if needed):] \mbox{}
495 % in case you have the need for further justifications why you chose this and that setting or if the settings do not fit into the standard Variant A or Variant B schema, please document this here
497 %%\item[References:] \todo{add references}
499 % add any further references or best practice documents here
501 %%\item[How to test:]
502 % describe here or point the admin to tools (can be a simple footnote or \ref{} to the tools section) which help the admin to test his settings.
508 \subsubsection{L2TP over IPSec}
509 \todo{write this subsubsection}
513 \item[Tested with Version:] \todo{version?}
515 \item[Settings:] \mbox{}
517 \begin{lstlisting}[breaklines]
518 %Here goes your setting string
521 \item[Additional settings:] \mbox{}
523 %Here you can add additional settings
525 \begin{lstlisting}[breaklines]
526 %copy \& paste additional settings
529 \item[Justification for special settings (if needed):] \mbox{}
531 % in case you have the need for further justifications why you chose this and that setting or if the settings do not fit into the standard Variant A or Variant B schema, please document this here
533 \item[References:] \todo{add references}
535 % add any further references or best practice documents here
538 % describe here or point the admin to tools (can be a simple footnote or \ref{} to the tools section) which help the admin to test his settings.
547 \subsubsection{Racoon}
548 \todo{write this subsubsection}
552 \item[Tested with Version:] \todo{version?}
554 \item[Settings:] \mbox{}
556 \begin{lstlisting}[breaklines]
557 %Here goes your setting string
560 \item[Additional settings:] \mbox{}
562 %Here you can add additional settings
564 \begin{lstlisting}[breaklines]
565 %copy \& paste additional settings
568 \item[Justification for special settings (if needed):] \mbox{}
570 % in case you have the need for further justifications why you chose this and that setting or if the settings do not fit into the standard Variant A or Variant B schema, please document this here
572 \item[References:] \todo{add references}
574 % add any further references or best practice documents here
577 % describe here or point the admin to tools (can be a simple footnote or \ref{} to the tools section) which help the admin to test his settings.