1 \section{Recommendations on practical settings}
2 \label{section:PracticalSettings}
5 \subsection{Webservers}
10 \item[Tested with Version:]
12 \item[Settings:] \mbox{}
14 %-All +TLSv1.1 +TLSv1.2
15 \begin{lstlisting}[breaklines]
16 SSLProtocol All -SSLv2 -SSLv3
17 SSLHonorCipherOrder On
19 # Add six earth month HSTS header for all users...
20 Header add Strict-Transport-Security "max-age=15768000"
21 # If you want to protect all subdomains, use the following header
22 # ALL subdomains HAVE TO support https if you use this!
23 # Strict-Transport-Security: max-age=15768000 ; includeSubDomains
25 SSLCipherSuite 'EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA'
28 Note again, that any cipher suite starting with ECDHE can be omitted in case of doubt.
29 %% XXX NOTE TO SELF: remove from future automatically generated lists!
31 \item[Additional settings:]
33 You should redirect everything to httpS:// if possible. In Apache you can do this with the following setting inside of a VirtualHost environment:
35 \begin{lstlisting}[breaklines]
39 RewriteRule ^.*$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R=permanent]
44 \item[Justification for special settings (if needed):]
49 %XXXX ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AES:RSA+3DES:!ADH:!AECDH:!MD5:!DSS
52 \subsubsection{lighttpd}
56 %% Note: need to be checked / reviewed
58 %% Complete ssl.cipher-list with same algo than Apache
59 \todo{FIXME: this string seems to be wrongly formatted}
61 \begin{lstlisting}[breaklines]
62 $SERVER["socket"] == "0.0.0.0:443" {
64 ssl.use-sslv2 = "disable"
65 ssl.use-sslv3 = "disable"
66 #ssl.use-compression obsolete >= 1.4.3.1
67 ssl.pemfile = "/etc/lighttpd/server.pem"
68 ssl.cipher-list = 'EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA'
69 ssl.honor-cipher-order = "enable"
70 setenv.add-response-header = ( "Strict-Transport-Security" => "max-age=31536000")
74 As for any other webserver, you should redirect automatically http traffic toward httpS:\footnote{That proposed configuration is directly coming from lighttpd documentation: \url{http://redmine.lighttpd.net/projects/1/wiki/HowToRedirectHttpToHttps}}
76 \begin{lstlisting}[breaklines]
77 $HTTP["scheme"] == "http" {
78 # capture vhost name with regex conditiona -> %0 in redirect pattern
79 # must be the most inner block to the redirect rule
80 $HTTP["host"] =~ ".*" {
81 url.redirect = (".*" => "https://%0$0")
90 \begin{lstlisting}[breaklines]
91 ssl_prefer_server_ciphers on;
92 ssl_protocols -SSLv2 -SSLv3;
93 ssl_ciphers 'EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA';
94 add_header Strict-Transport-Security max-age=2592000;
95 add_header X-Frame-Options DENY;
98 %% XXX FIXME: do we need to specify dhparams? Parameter: ssl_dhparam = file. See: http://wiki.nginx.org/HttpSslModule#ssl_protocols
101 If you decide to trust NIST's ECC curve recommendation, you can add the following line to nginx's configuration file to select special curves:
103 \begin{lstlisting}[breaklines]
104 ssl_ecdh_curve sect571k1;
107 You should redirect everything to httpS:// if possible. In Nginx you can do this with the following setting:
109 \begin{lstlisting}[breaklines]
110 rewrite ^(.*) https://$host$1 permanent;
113 %\subsubsection{openssl.conf settings}
115 %\subsubsection{Differences in SSL libraries: gnutls vs. openssl vs. others}
117 \subsubsection{MS IIS}
122 When trying to avoid RC4 and CBC (BEAST-Attack) and requiring perfect
123 forward secrecy, Microsoft Internet Information Server (IIS) supports
124 ECDSA, but does not support RSA for key exchange (consider ECC suite
125 B doubts\footnote{\url{http://safecurves.cr.yp.to/rigid.html}}).
127 Since \verb|ECDHE_RSA_*| is not supported, a SSL certificate based on
128 elliptic curves needs to be used.
130 The configuration of cipher suites MS IIS will use can be configured in one
131 of the following ways:
133 \item Group Policy \footnote{\url{http://msdn.microsoft.com/en-us/library/windows/desktop/bb870930(v=vs.85).aspx}}
135 \item IIS Crypto~\footnote{\url{https://www.nartac.com/Products/IISCrypto/}}
139 Table~\ref{tab:MS_IIS_Client_Support} shows the process of turning on
140 one algorithm after another and the effect on the supported Clients
141 tested using https://www.ssllabs.com.
143 \verb|SSL 3.0|, \verb|SSL 2.0| and \verb|MD5| are turned off.
144 \verb|TLS 1.0| and \verb|TLS 2.0| are turned on.
151 Cipher Suite & Client \\
153 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256| & only IE 10,11, OpenSSL 1.0.1e \\
154 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256| & Chrome 30, Opera 17, Safari 6+ \\
155 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA| & FF 10-24, IE 8+, Safari 5, Java 7\\
158 \caption{Client support}
159 \label{tab:MS_IIS_Client_Support}
162 Table~\ref{tab:MS_IIS_Client_Support} shows the algoriths from
163 strongest to weakest and why they need to be added in this order. For
164 example insiting on SHA-2 algorithms (only first two lines) would
165 eliminate all versions of Firefox, so the last line is needed to
166 support this browser, but should be placed at the bottom, so capable
167 browsers will choose the stronger SHA-2 algorithms.
169 \verb|TLS_RSA_WITH_RC4_128_SHA| or equivalent should also be added if
170 MS Terminal Server Connection is used (make sure to use this only in a
171 trusted environment). This suite will not be used for SSL, since we do
175 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256| ... only supported by: IE 10,11, OpenSSL 1.0.1e
176 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256| ... Chrome 30, Opera 17, Safari 6+
177 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA| ... Firefox 10-24, IE 8+, Safari 5, Java 7
180 Not supported Clients:
188 \subsection{Mail Servers}
190 This section documents the most common mail (SMTP) and IMAPs/POPs servers. Another option to secure IMAPs/POPs servers is to place them behind an stunnel server.
192 \subsubsection{Dovecot}
197 % Example: http://dovecot.org/list/dovecot/2013-October/092999.html
199 \begin{lstlisting}[breaklines]
200 ssl_cipher_list = 'EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA'
201 ssl_prefer_server_ciphers = yes
204 Dovecot 2.1: Almost as good as dovecot 2.2. Does not support ssl\_prefer\_server\_ciphers
206 \paragraph*{Limitations}\mbox{}\\
208 Dovecot currently does not support disabling TLS compression. Furthermore, DH parameters
209 greater than 1024bit aren't possible. The most recent version 2.2.7 of Dovecot implements
210 configurable DH parameter length
211 \footnote{\url{http://hg.dovecot.org/dovecot-2.2/rev/43ab5abeb8f0}}.
213 \subsubsection{cyrus-imapd (based on 2.4.17)}
215 \paragraph*{imapd.conf}\mbox{}\\
217 To activate SSL/TLS configure your certificate with
218 \begin{lstlisting}[breaklines]
219 tls_cert_file: .../cert.pem
220 tls_key_file: .../cert.key
223 Do not forget to add necessary intermediate certificates to the .pem file.\\
225 Limiting the ciphers provided may force (especially older) clients to connect without encryption at all! Sticking to the defaults is recommended.\\
227 If you still want to force strong encryption use
228 \begin{lstlisting}[breaklines]
229 tls_cipher_list: <...recommended ciphersuite...>
232 cyrus-imapd loads hardcoded 1024 bit DH parameters using get\_rfc2409\_prime\_1024() by default. If you want to load your own DH parameters add them PEM encoded to the certificate file given in tls\_cert\_file. Do not forget to re-add them after updating your certificate.
234 \paragraph*{cyrus.conf}\mbox{}\\
236 To support POP3/IMAP on ports 110/143 with STARTTLS add
237 \begin{lstlisting}[breaklines]
238 imap cmd="imapd" listen="imap" prefork=3
239 pop3 cmd="pop3d" listen="pop3" prefork=1
241 to the SERVICES section.\\
243 To support POP3S/IMAPS on ports 995/993 add
244 \begin{lstlisting}[breaklines]
245 imaps cmd="imapd -s" listen="imaps" prefork=3
246 pop3s cmd="pop3d -s" listen="pop3s" prefork=1
249 \paragraph*{Limitations}\mbox{}\\
251 cyrus-imapd currently (2.4.17, trunk) does not support elliptic curves. ECDHE will not work even if defined in your cipher list.\\
253 Currently there is no way to prefer server ciphers or to disable compression.\\
255 There is a working patch for all three features:
256 \url{https://bugzilla.cyrusimap.org/show_bug.cgi?id=3823}\\
258 There is no way to prevent unencrypted connections on the STARTTLS ports. You can prevent usage of plaintext login by setting
259 \begin{lstlisting}[breaklines]
262 in imapd.conf. But note that SASL PLAIN/LOGIN is still available!\\
267 % XXX config von Adi?
269 % ciphers = EDH+CAMELLIA256:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:-AES128:!CAMELLIA128:!ECDSA:AES256-SHA:EDH+AES128;
270 % options = CIPHER_SERVER_PREFERENCE
273 \subsubsection{SMTP in general}
275 SMTP usually uses opportunistic TLS. This means that an MTA will accept TLS connections when asked for it during handshake but will not require it. One should always support incoming opportunistic TLS and always try TLS handshake outgoing.\\
277 Furthermore a mailserver can operate in three modes:
279 \item As MSA (Mail Submission Agent) your mailserver receives mail from your clients MUAs (Mail User Agent).
280 \item As receiving MTA (Mail Transmission Agent, MX)
281 \item As sending MTA (SMTP client)
284 We recommend the following basic setup for all modes:
286 \item correctly setup MX, A and PTR RRs without using CNAMEs at all.
287 \item enable encryption (opportunistic TLS)
288 \item do not use self signed certificates
291 For SMTP client mode we additionally recommend:
293 \item the hostname used as HELO must match the PTR RR
294 \item setup a client certificate (most server certificates are client certificates as well)
295 \item either the common name or at least an alternate subject name of your certificate must match the PTR RR
296 \item do not modify the cipher suite for client mode
299 For MSA operation we recommend:
301 \item listen on submission port 587
302 \item enforce SMTP AUTH even for local networks
303 \item do not allow SMTP AUTH on unencrypted connections
304 \item optionally use the recommended cipher suites if (and only if) all your connecting MUAs support them
309 % Note that (with the exception of MSA mode), it might be better to allow any cipher suite -- since any encryption is better than no encryption when it comes to opportunistic TLS.
311 We strongly recommend to allow all cipher suites for anything but MSA
312 mode, because the alternative is plain text transmission.
314 \subsubsection{Postfix}
316 \todo{cm: document DANE}
318 First, you need to generate Diffie Hellman parameters (please first take a look at the section \ref{section:PRNG}):
320 \todo{FIXME: this is a really weak setting! See also: http://postfix.1071664.n5.nabble.com/postfix-hardening-what-can-we-do-td61874.html}
321 \begin{lstlisting}[breaklines]
322 % openssl gendh -out /etc/postfix/dh_param_512.pem -2 512
323 % openssl gendh -out /etc/postfix/dh_param_1024.pem -2 1024
326 Next, we specify these DH parameters in \verb|main.cf|:
328 \begin{lstlisting}[breaklines]
329 smtpd_tls_dh512_param_file = /etc/postfix/dh_param_512.pem
330 smtpd_tls_dh1024_param_file = /etc/postfix/dh_param_1024.pem
333 \paragraph*{MX and SMTP client configuration}\mbox{}\\
335 As discussed above, because of opportunistic encryption we do not
336 restrict the list of ciphers. There's still some steps needed to
337 enable TLS, all in \verb|main.cf| \footnote{Refer to
338 \url{http://www.postfix.org/TLS_README.html} for an in-depth
341 \begin{lstlisting}[breaklines]
342 smtpd_tls_cert_file = /etc/postfix/server.pem
343 smtpd_tls_key_file = /etc/postfix/server.key
344 # use 0 for Postfix >= 2.9, and 1 for earlier versions
345 smtpd_tls_loglevel = 0
346 # enable opportunistic TLS support in the SMTP server and client
347 smtpd_tls_security_level = may
348 smtp_tls_security_level = may
349 # if you have authentication enabled, only offer it after STARTTLS
350 smtpd_tls_auth_only = yes
351 tls_ssl_options=NO_COMPRESSION
352 tls_random_source = dev:/dev/urandom
355 \paragraph*{MSA}\mbox{}\\
357 For the MSA \verb|smtpd| process, we first define the ciphers that are
358 acceptable for the ``mandatory'' security level, again in
361 \begin{lstlisting}[breaklines]
362 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
363 smtpd_tls_mandatory_ciphers=high
364 tls_high_cipherlist='EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA'
367 Then, we configure the MSA smtpd in \verb|master.cf| with two
368 additional options that are only used for this instance of smtpd:
370 \begin{lstlisting}[breaklines]
371 587 inet n - - - - smtpd
372 -o smtpd_tls_security_level=encrypt -o tls_preempt_cipherlist = yes
375 For those users who want to use ECC key exchange, it is possible to specify this via:
376 \begin{lstlisting}[breaklines]
377 smtpd_tls_eecdh_grade = ultra
380 You can check the settings with the following command:
381 \begin{lstlisting}[breaklines]
382 $ zegrep "TLS connection established from.*with cipher" | /var/log/mail.log | awk '{printf("%s %s %s %s\n", $12, $13, $14, $15)}' | sort | uniq -c | sort -n
383 1 SSLv3 with cipher DHE-RSA-AES256-SHA
384 23 TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384
385 60 TLSv1 with cipher ECDHE-RSA-AES256-SHA
386 270 TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384
387 335 TLSv1 with cipher DHE-RSA-AES256-SHA
390 \paragraph*{Limitations}\mbox{}\\
392 tls\_ssl\_options is supported from Postfix 2.11 onwards. You can
393 leave the statement in the configuration for older versions, it will
396 tls\_preempt\_cipherlist is supported from Postfix 2.8 onwards. Again,
397 you can leave the statement in for older versions.
399 \subsubsection{Exim (based on 4.82)}
401 It is highly recommended to read
403 \url{http://exim.org/exim-html-current/doc/html/spec_html/ch-encrypted_smtp_connections_using_tlsssl.html}
407 \paragraph*{MSA mode (submission)}\mbox{}\\
409 In the main config section of Exim add:
411 \begin{lstlisting}[breaklines]
412 tls_certificate = ..../cert.pem
413 tls_privatekey = ..../cert.key
415 don't forget to add intermediate certificates to the .pem file if needed.\\
417 Tell Exim to advertise STARTTLS in the EHLO answer to everyone:
418 \begin{lstlisting}[breaklines]
419 tls_advertise_hosts = *
422 If you want to support legacy SMTPS on port 465, and STARTTLS on smtp(25)/submission(587) ports set
423 \begin{lstlisting}[breaklines]
424 daemon_smtp_ports = smtp : smtps : submission
425 tls_on_connect_ports = 465
428 It is highly recommended to limit SMTP AUTH to SSL connections only. To do so add
429 \begin{lstlisting}[breaklines]
430 server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}}
432 to every authenticator defined.\\
434 Add the following rules on top of your acl\_smtp\_mail:
435 \begin{lstlisting}[breaklines]
437 control = submission/sender_retain
439 This switches Exim to submission mode and allows addition of missing Message-ID: and Date: headers.\\
441 It is not advisable to restrict the default cipher list for MSA mode if you don't know all connecting MUAs. If you still want to define one please consult the Exim documentation or ask on the exim-users mailinglist.\\
442 % Exim maintainers do not recommend to change default ciphers
443 % I think we shouldn't, too
445 %\begin{lstlisting}[breaklines]
446 % tls_require_ciphers = <...recommended ciphersuite...>
449 The cipher used is written to the logfiles by default. You may want to add
450 \begin{lstlisting}[breaklines]
451 log_selector = <....whatever your log_selector already contains...> \
452 +tls_certificate_verified +tls_peerdn +tls_sni
454 to get even more TLS information logged.
457 \paragraph*{server mode (incoming)}\mbox{}\\
459 In the main config section of Exim add:
461 \begin{lstlisting}[breaklines]
462 tls_certificate = ..../cert.pem
463 tls_privatekey = ..../cert.key
465 don't forget to add intermediate certificates to the .pem file if needed.\\
467 Tell Exim to advertise STARTTLS in the EHLO answer to everyone:
468 \begin{lstlisting}[breaklines]
469 tls_advertise_hosts = *
472 Listen on smtp(25) port only
473 \begin{lstlisting}[breaklines]
474 daemon_smtp_ports = smtp
477 It is not advisable to restrict the default cipher list for opportunistic encryption as used by SMTP. Do not use cipher lists recommended for HTTPS! If you still want to define one please consult the Exim documentation or ask on the exim-users mailinglist.\\
478 % Exim maintainers do not recommend to change default ciphers
481 %\begin{lstlisting}[breaklines]
482 % tls_require_ciphers = <...recommended ciphersuite...>
485 If you want to request and verify client certificates from sending hosts set
486 \begin{lstlisting}[breaklines]
487 tls_verify_certificates = /etc/pki/tls/certs/ca-bundle.crt
488 tls_try_verify_hosts = *
491 tls\_try\_verify\_hosts only reports the result to your logfile. If you want to disconnect such clients you have to use
492 \begin{lstlisting}[breaklines]
496 The cipher used is written to the logfiles by default. You may want to add
497 \begin{lstlisting}[breaklines]
498 log_selector = <....whatever your log_selector already contains...> \
499 +tls_certificate_verified +tls_peerdn +tls_sni
501 to get even more TLS information logged.
503 \paragraph*{client mode (outgoing)}\mbox{}\\
505 Exim uses opportunistic encryption in the SMTP transport by default.
507 Client mode settings have to be done in the configuration section of the smtp transport (driver = smtp).
509 If you want to use a client certificate (most server certificates can be used as client certificate, too) set
510 \begin{lstlisting}[breaklines]
511 tls_certificate = .../cert.pem
512 tls_privatekey = .../cert.key
514 This is recommended for MTA-MTA traffic.\\
516 %If you want to limit used ciphers set
517 %\begin{lstlisting}[breaklines]
518 % tls_require_ciphers = <...recommended ciphersuite...>
520 % Exim Maintainers do not recommend ciphers. We shouldn't do so, too.
521 Do not limit ciphers without a very good reason. In the worst case you end up without encryption at all instead of some weak encryption. Please consult the Exim documentation if you really need to define ciphers.
523 \paragraph*{OpenSSL}\mbox{}\\
524 Exim already disables SSLv2 by default. We recommend to add
525 \begin{lstlisting}[breaklines]
526 openssl_options = +all +no_sslv2 +no_compression +cipher_server_preference
528 to the main configuration.\\
529 Note: +all is misleading here since OpenSSL only activates the most common workarounds. But that's how SSL\_OP\_ALL is defined.\\
531 You do not need to set dh\_parameters. Exim with OpenSSL by default uses parameter initialization with the "2048-bit MODP Group with 224-bit Prime Order Subgroup" defined in section 2.2 of RFC 5114 (ike23).
532 If you want to set your own DH parameters please read the TLS documentation of exim.\\
536 \paragraph*{GnuTLS}\mbox{}\\
538 GnuTLS is different in only some respects to OpenSSL:
540 \item tls\_require\_ciphers needs a GnuTLS priority string instead of a cipher list. It is recommended to use the defaults by not defining this option. It highly depends on the version of GnuTLS used. Therefore it is not advisable to change the defaults.
541 \item There is no option like openssl\_options
544 \paragraph*{Exim string expansion}\mbox{}\\
546 Note that most of the options accept expansion strings. This way you can eg. set cipher lists or STARTTLS advertisment conditionally. Please follow the link to the official Exim documentation to get more information.
548 \paragraph*{Limitations}\mbox{}\\
550 Exim currently (4.82) does not support elliptic curves with OpenSSL. This means that ECDHE is not used even if defined in your cipher list.
551 There already is a working patch to provide support:\\
552 \url{http://bugs.exim.org/show_bug.cgi?id=1397}
555 % do we need to documment starttls in detail?
556 %\subsubsection{starttls?}
560 \begin{lstlisting}[breaklines]
562 PermitEmptyPasswords no
565 HostKey /etc/ssh/ssh_host_rsa_key
567 MACs hmac-sha2-512,hmac-sha2-256,hmac-ripemd160
568 KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
571 % XXX: curve25519-sha256@libssh.org only available upstream(!)
572 Note: older linux systems won't support SHA2, PuTTY does not support RIPE-MD160.
577 \todo{write this subsection}
578 \subsubsection{IPSec}
580 \todo{cm: check if there are downgrade attacks for checkpoint \& co} \\
581 \todo{cm: reference the paper describing how complex IPSec is and that it can't be checked properly} \\
582 \todo{cm: change this to a table format: Variant ((A,B), (recommendations, recommendations))} \\
584 \paragraph*{Assumptions}\mbox{}\\
586 We assume the usage of IKE (v1 or v2) for this document, and ESP.
588 \paragraph*{Authentication}\mbox{}\\
590 IPSEC authentication should optimally be performed via RSA signatures,
591 with a key size of 2048 bits or more. Configuring only the trusted CA
592 that issued the peer certificate provides for additional protection
593 against fake certificates.
595 If you need to use Pre-Shared Key authentication:
598 \item Choose a \textbf{random} PSK of 20 characters or more (\todo{length, references!})
599 \item Use a \textbf{separate} PSK for any IPSEC connection
600 \item Change the PSKs regularily
603 \paragraph*{Cryptographic Suites}\mbox{}\\
605 IPSEC Cryptographic Suites are pre-defined settings for all the
606 items of a configuration; they try to provide a balanced security
607 level and make setting up VPNs easier.
609 When using any of those suites, make sure to enable ``Perfect Forward
610 Secrecy`` for Phase 2, as this is not specified in the suites.
612 \verb|Suite-B-GCM-256| \footnote{\url{http://tools.ietf.org/html/rfc6379}}
613 would be roughly equivalent to ``Configuration A``, but keep in mind
614 that it uses NIST elliptic curves for the Diffie-Hellman key exchange.
616 \verb|Suite-B-GCM-128| or
617 \verb|VPN-B| \footnote{\url{http://tools.ietf.org/html/rfc4308}} would
618 be roughly equivalent to ``Configuration B``; again,
619 \verb|Suite-B-GCM-128| uses NIST elliptic curves, \verb|VPN-B| does
622 \todo{Aaron: make an example for how to include images}
623 \todo{cm: screenshots of Checkpoint settings}
625 \paragraph*{IKE or Phase 1}\mbox{}\\
627 IKE or Phase 1 is the mutual authentication and key exchange phase.
629 Use only ``main mode``, as ``aggressive mode`` has known security
630 vulnerabilities \footnote{\url{http://ikecrack.sourceforge.net/}}.
632 Encryption Algorithm: AES or CAMELLIA
634 Hash Algorithm: SHA2-256, SHA2-384 or SHA2-512
636 DH Group: Group 14--18 (2048--8192 bit DH), or 19-21 (256--521 bit
639 Lifetime: \todo{need recommendations; 1 day seems to be common practice}
641 \todo{what about CAST?}
643 \paragraph*{ESP or Phase 2}\mbox{}\\
645 Enable ``Perfect Forward Secrecy`` with a DH Group equivalent to the
648 Encryption Algorithm: AES-GCM-16, AES-CTR, AES-CCM-16, AES-CBC, SEED
649 or CAMELLIA \todo{order of this list?}
651 Hash Algorithm: none (if using AES-GCM), HMAC-SHA-SHA256 or longer
652 \todo{what about AES-XCBC-MAC?}
654 Lifetime: \todo{need recommendations; 1--8 hours seems to be common practice}
657 \subsubsection{OpenVPN}
658 \todo{cm: please write this subsubsection}
659 \todo{WARNING - Section Writing in progress...}
660 \todo{We suppose user uses easy-rsa which is roughly used in all HOWTO}
662 \paragraph{Fine tuning at installation level}
664 When installing an OpenVPN server instance, you are probably using {\it easy-rsa} tools to generate the crypto stuff needed.
665 From the directory where you will run them, you can enhance you configuration by changing the following variables in {\it Vars}
667 \begin{lstlisting}[breaklines]
671 This will enhance the security of the key exchange steps by using RSA keys with a length of 2048 bits.
673 \todo{Shouldn't we need to reduce CA and certificate lifetime? Per default 10y!!}
676 \paragraph{Server Configuration}
678 \todo{To write - locked by David}
680 \begin{lstlisting}[breaklines]
681 cipher AES-128-CBC # AES
685 \paragraph{Client Configuration}
687 \todo{To write - locked by David}
689 \begin{lstlisting}[breaklines]
696 \todo{cm: please write this subsubsection}
698 \subsubsection{Cisco IPSec}
699 \todo{write this subsubsection}
701 \subsubsection{Juniper VPN}
702 \todo{write this subsubsection. AK: ask Hannes}
704 \subsubsection{L2TP over IPSec}
705 \todo{write this subsubsection}
707 \subsubsection{Racoon}
708 \todo{write this subsubsection}
711 \subsection{PGP/ GPG - Pretty Good Privacy}
713 \todo{re-work this subsection -- this is still only a draft!!}
716 \subsection{seclayer-tcp}
717 \todo{Ramin: please write this section or ask Posch}
718 For the austrian citizen card....
721 seclayer-tcp 3495/udp # securitylayer over tcp
722 seclayer-tcp 3495/tcp # securitylayer over tcp
726 \subsection{IPMI, ILO and other lights out management solutions}
727 \todo{write this!! Recommendation. Empfehlung: nie ins Internet, nur in ein eigenes mgmt VLAN, das via VPN erreichbar ist!!
731 \todo{AK: ask Klaus. Write this section, Klaus??? }
733 \subsection{Instant Messaging Systems}
734 \subsubsection{XMPP / Jabber}
735 \todo{ts: Describe ejabberd configuration. Reference to Peter`s manifesto https://github.com/stpeter/manifesto}
740 \input{proxy_solutions}
746 %%% TeX-master: "applied-crypto-hardening"