1 \section{Recommendations on practical settings}
4 \subsection{Webservers}
9 \item[Tested with Version:]
11 \item[Settings:] \mbox{}
13 %-All +TLSv1.1 +TLSv1.2
14 \begin{lstlisting}[breaklines]
15 SSLProtocol All -SSLv2 -SSLv3
16 SSLHonorCipherOrder On
18 # Add six earth month HSTS header for all users...
19 Header add Strict-Transport-Security "max-age=15768000"
20 # If you want to protect all subdomains, use the following header
21 # ALL subdomains HAVE TO support https if you use this!
22 # Strict-Transport-Security: max-age=15768000 ; includeSubDomains
24 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'
27 Note again, that any cipher suite starting with ECDHE can be omitted in case of doubt.
28 %% XXX NOTE TO SELF: remove from future automatically generated lists!
30 \item[Additional settings:]
32 You should redirect everything to httpS:// if possible. In Apache you can do this with the following setting inside of a VirtualHost environment:
34 \begin{lstlisting}[breaklines]
38 RewriteRule ^.*$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R=permanent]
43 \item[Justification for special settings (if needed):]
48 %XXXX ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AES:RSA+3DES:!ADH:!AECDH:!MD5:!DSS
51 \subsubsection{lighttpd}
55 %% Note: need to be checked / reviewed
57 %% Complete ssl.cipher-list with same algo than Apache
58 \todo{FIXME: this string seems to be wrongly formatted}
60 \begin{lstlisting}[breaklines]
61 $SERVER["socket"] == "0.0.0.0:443" {
63 ssl.use-sslv2 = "disable"
64 ssl.use-sslv3 = "disable"
65 #ssl.use-compression obsolete >= 1.4.3.1
66 ssl.pemfile = "/etc/lighttpd/server.pem"
67 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'
68 ssl.honor-cipher-order = "enable"
69 setenv.add-response-header = ( "Strict-Transport-Security" => "max-age=31536000")
73 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}}
75 \begin{lstlisting}[breaklines]
76 $HTTP["scheme"] == "http" {
77 # capture vhost name with regex conditiona -> %0 in redirect pattern
78 # must be the most inner block to the redirect rule
79 $HTTP["host"] =~ ".*" {
80 url.redirect = (".*" => "https://%0$0")
89 \begin{lstlisting}[breaklines]
90 ssl_prefer_server_ciphers on;
91 ssl_protocols -SSLv2 -SSLv3;
92 ssl_ciphers 'EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EDH+CAMELLIA256:EECDH:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:!AES128:!CAMELLIA128:!ECDSA:AES256-SHA';
93 add_header Strict-Transport-Security max-age=2592000;
94 add_header X-Frame-Options DENY;
97 %% XXX FIXME: do we need to specify dhparams? Parameter: ssl_dhparam = file. See: http://wiki.nginx.org/HttpSslModule#ssl_protocols
100 If you decide to trust NIST's ECC curve recommendation, you can add the following line to nginx's configuration file to select special curves:
102 \begin{lstlisting}[breaklines]
103 ssl_ecdh_curve sect571k1;
106 You should redirect everything to httpS:// if possible. In Nginx you can do this with the following setting:
108 \begin{lstlisting}[breaklines]
109 rewrite ^(.*) https://$host$1 permanent;
112 %\subsubsection{openssl.conf settings}
114 %\subsubsection{Differences in SSL libraries: gnutls vs. openssl vs. others}
116 \subsubsection{MS IIS}
121 When trying to avoid RC4 and CBC (BEAST-Attack) and requiring perfect
122 forward secrecy, Microsoft Internet Information Server (IIS) supports
123 ECDSA, but does not support RSA for key exchange (consider ECC suite
124 B doubts\footnote{\url{http://safecurves.cr.yp.to/rigid.html}}).
126 Since \verb|ECDHE_RSA_*| is not supported, a SSL certificate based on
127 elliptic curves needs to be used.
129 The configuration of cipher suites MS IIS will use can be configured in one
130 of the following ways:
132 \item Group Policy \footnote{\url{http://msdn.microsoft.com/en-us/library/windows/desktop/bb870930(v=vs.85).aspx}}
134 \item IIS Crypto~\footnote{\url{https://www.nartac.com/Products/IISCrypto/}}
138 Table~\ref{tab:MS_IIS_Client_Support} shows the process of turning on
139 one algorithm after another and the effect on the supported Clients
140 tested using https://www.ssllabs.com.
142 \verb|SSL 3.0|, \verb|SSL 2.0| and \verb|MD5| are turned off.
143 \verb|TLS 1.0| and \verb|TLS 2.0| are turned on.
150 Cipher Suite & Client \\
152 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256| & only IE 10,11, OpenSSL 1.0.1e \\
153 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256| & Chrome 30, Opera 17, Safari 6+ \\
154 \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA| & FF 10-24, IE 8+, Safari 5, Java 7\\
157 \caption{Client support}
158 \label{tab:MS_IIS_Client_Support}
161 Table~\ref{tab:MS_IIS_Client_Support} shows the algoriths from
162 strongest to weakest and why they need to be added in this order. For
163 example insiting on SHA-2 algorithms (only first two lines) would
164 eliminate all versions of Firefox, so the last line is needed to
165 support this browser, but should be placed at the bottom, so capable
166 browsers will choose the stronger SHA-2 algorithms.
168 \verb|TLS_RSA_WITH_RC4_128_SHA| or equivalent should also be added if
169 MS Terminal Server Connection is used (make sure to use this only in a
170 trusted environment). This suite will not be used for SSL, since we do
174 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256| ... only supported by: IE 10,11, OpenSSL 1.0.1e
175 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256| ... Chrome 30, Opera 17, Safari 6+
176 % \verb|TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA| ... Firefox 10-24, IE 8+, Safari 5, Java 7
179 Not supported Clients:
187 \subsection{Mail Servers}
189 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.
191 \subsubsection{Dovecot}
196 % Example: http://dovecot.org/list/dovecot/2013-October/092999.html
198 \begin{lstlisting}[breaklines]
199 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'
200 ssl_prefer_server_ciphers = yes
203 Dovecot 2.1: Almost as good as dovecot 2.2. Does not support ssl\_prefer\_server\_ciphers
205 \paragraph*{Limitations}\mbox{}\\
207 Dovecot currently does not support disabling TLS compression. Furthermore, DH parameters
208 greater than 1024bit aren't possible. The most recent version 2.2.7 of Dovecot implements
209 configurable DH parameter length
210 \footnote{\url{http://hg.dovecot.org/dovecot-2.2/rev/43ab5abeb8f0}}.
212 \subsubsection{cyrus-imapd (based on 2.4.17)}
214 \paragraph*{imapd.conf}\mbox{}\\
216 To activate SSL/TLS configure your certificate with
217 \begin{lstlisting}[breaklines]
218 tls_cert_file: .../cert.pem
219 tls_key_file: .../cert.key
222 Do not forget to add necessary intermediate certificates to the .pem file.\\
224 Limiting the ciphers provided may force (especially older) clients to connect without encryption at all! Sticking to the defaults is recommended.\\
226 If you still want to force strong encryption use
227 \begin{lstlisting}[breaklines]
228 tls_cipher_list: <...recommended ciphersuite...>
231 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.
233 \paragraph*{cyrus.conf}\mbox{}\\
235 To support POP3/IMAP on ports 110/143 with STARTTLS add
236 \begin{lstlisting}[breaklines]
237 imap cmd="imapd" listen="imap" prefork=3
238 pop3 cmd="pop3d" listen="pop3" prefork=1
240 to the SERVICES section.\\
242 To support POP3S/IMAPS on ports 995/993 add
243 \begin{lstlisting}[breaklines]
244 imaps cmd="imapd -s" listen="imaps" prefork=3
245 pop3s cmd="pop3d -s" listen="pop3s" prefork=1
248 \paragraph*{Limitations}\mbox{}\\
250 cyrus-imapd currently (2.4.17, trunk) does not support elliptic curves. ECDHE will not work even if defined in your cipher list.\\
252 Currently there is no way to prefer server ciphers or to disable compression.\\
254 There is a working patch for all three features:
255 \url{https://bugzilla.cyrusimap.org/show_bug.cgi?id=3823}\\
257 There is no way to prevent unencrypted connections on the STARTTLS ports. You can prevent usage of plaintext login by setting
258 \begin{lstlisting}[breaklines]
261 in imapd.conf. But note that SASL PLAIN/LOGIN is still available!\\
266 % XXX config von Adi?
268 % ciphers = EDH+CAMELLIA256:EDH+aRSA:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED:-AES128:!CAMELLIA128:!ECDSA:AES256-SHA:EDH+AES128;
269 % options = CIPHER_SERVER_PREFERENCE
272 \subsubsection{SMTP in general}
274 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.\\
276 Furthermore a mailserver can operate in three modes:
278 \item As MSA (Mail Submission Agent) your mailserver receives mail from your clients MUAs (Mail User Agent).
279 \item As receiving MTA (Mail Transmission Agent, MX)
280 \item As sending MTA (SMTP client)
283 We recommend the following basic setup for all modes:
285 \item correctly setup MX, A and PTR RRs without using CNAMEs at all.
286 \item enable encryption (opportunistic TLS)
287 \item do not use self signed certificates
290 For SMTP client mode we additionally recommend:
292 \item the hostname used as HELO must match the PTR RR
293 \item setup a client certificate (most server certificates are client certificates as well)
294 \item either the common name or at least an alternate subject name of your certificate must match the PTR RR
295 \item do not modify the cipher suite for client mode
298 For MSA operation we recommend:
300 \item listen on submission port 587
301 \item enforce SMTP AUTH even for local networks
302 \item do not allow SMTP AUTH on unencrypted connections
303 \item optionally use the recommended cipher suites if (and only if) all your connecting MUAs support them
308 % 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.
310 We strongly recommend to allow all cipher suites for anything but MSA
311 mode, because the alternative is plain text transmission.
313 \subsubsection{Postfix}
315 \todo{cm: document DANE}
317 First, you need to generate Diffie Hellman parameters (please first take a look at the section \ref{section:PRNG}):
319 \todo{FIXME: this is a really weak setting! See also: http://postfix.1071664.n5.nabble.com/postfix-hardening-what-can-we-do-td61874.html}
320 \begin{lstlisting}[breaklines]
321 % openssl gendh -out /etc/postfix/dh_param_512.pem -2 512
322 % openssl gendh -out /etc/postfix/dh_param_1024.pem -2 1024
325 Next, we specify these DH parameters in \verb|main.cf|:
327 \begin{lstlisting}[breaklines]
328 smtpd_tls_dh512_param_file = /etc/postfix/dh_param_512.pem
329 smtpd_tls_dh1024_param_file = /etc/postfix/dh_param_1024.pem
332 \paragraph*{MX and SMTP client configuration}\mbox{}\\
334 As discussed above, because of opportunistic encryption we do not
335 restrict the list of ciphers. There's still some steps needed to
336 enable TLS, all in \verb|main.cf| \footnote{Refer to
337 \url{http://www.postfix.org/TLS_README.html} for an in-depth
340 \begin{lstlisting}[breaklines]
341 smtpd_tls_cert_file = /etc/postfix/server.pem
342 smtpd_tls_key_file = /etc/postfix/server.key
343 # use 0 for Postfix >= 2.9, and 1 for earlier versions
344 smtpd_tls_loglevel = 0
345 # enable opportunistic TLS support in the SMTP server and client
346 smtpd_tls_security_level = may
347 smtp_tls_security_level = may
348 # if you have authentication enabled, only offer it after STARTTLS
349 smtpd_tls_auth_only = yes
350 tls_ssl_options=NO_COMPRESSION
351 tls_random_source = dev:/dev/urandom
354 \paragraph*{MSA}\mbox{}\\
356 For the MSA \verb|smtpd| process, we first define the ciphers that are
357 acceptable for the ``mandatory'' security level, again in
360 \begin{lstlisting}[breaklines]
361 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
362 smtpd_tls_mandatory_ciphers=high
363 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'
366 Then, we configure the MSA smtpd in \verb|master.cf| with two
367 additional options that are only used for this instance of smtpd:
369 \begin{lstlisting}[breaklines]
370 587 inet n - - - - smtpd
371 -o smtpd_tls_security_level=encrypt -o tls_preempt_cipherlist = yes
374 For those users who want to use ECC key exchange, it is possible to specify this via:
375 \begin{lstlisting}[breaklines]
376 smtpd_tls_eecdh_grade = ultra
379 You can check the settings with the following command:
380 \begin{lstlisting}[breaklines]
381 $ 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
382 1 SSLv3 with cipher DHE-RSA-AES256-SHA
383 23 TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384
384 60 TLSv1 with cipher ECDHE-RSA-AES256-SHA
385 270 TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384
386 335 TLSv1 with cipher DHE-RSA-AES256-SHA
389 \paragraph*{Limitations}\mbox{}\\
391 tls\_ssl\_options is supported from Postfix 2.11 onwards. You can
392 leave the statement in the configuration for older versions, it will
395 tls\_preempt\_cipherlist is supported from Postfix 2.8 onwards. Again,
396 you can leave the statement in for older versions.
398 \subsubsection{Exim (based on 4.82)}
400 It is highly recommended to read
402 \url{http://exim.org/exim-html-current/doc/html/spec_html/ch-encrypted_smtp_connections_using_tlsssl.html}
406 \paragraph*{MSA mode (submission)}\mbox{}\\
408 In the main config section of Exim add:
410 \begin{lstlisting}[breaklines]
411 tls_certificate = ..../cert.pem
412 tls_privatekey = ..../cert.key
414 don't forget to add intermediate certificates to the .pem file if needed.\\
416 Tell Exim to advertise STARTTLS in the EHLO answer to everyone:
417 \begin{lstlisting}[breaklines]
418 tls_advertise_hosts = *
421 If you want to support legacy SMTPS on port 465, and STARTTLS on smtp(25)/submission(587) ports set
422 \begin{lstlisting}[breaklines]
423 daemon_smtp_ports = smtp : smtps : submission
424 tls_on_connect_ports = 465
427 It is highly recommended to limit SMTP AUTH to SSL connections only. To do so add
428 \begin{lstlisting}[breaklines]
429 server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}}
431 to every authenticator defined.\\
433 Add the following rules on top of your acl\_smtp\_mail:
434 \begin{lstlisting}[breaklines]
436 control = submission/sender_retain
438 This switches Exim to submission mode and allows addition of missing Message-ID: and Date: headers.\\
440 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.\\
441 % Exim maintainers do not recommend to change default ciphers
442 % I think we shouldn't, too
444 %\begin{lstlisting}[breaklines]
445 % tls_require_ciphers = <...recommended ciphersuite...>
448 The cipher used is written to the logfiles by default. You may want to add
449 \begin{lstlisting}[breaklines]
450 log_selector = <....whatever your log_selector already contains...> \
451 +tls_certificate_verified +tls_peerdn +tls_sni
453 to get even more TLS information logged.
456 \paragraph*{server mode (incoming)}\mbox{}\\
458 In the main config section of Exim add:
460 \begin{lstlisting}[breaklines]
461 tls_certificate = ..../cert.pem
462 tls_privatekey = ..../cert.key
464 don't forget to add intermediate certificates to the .pem file if needed.\\
466 Tell Exim to advertise STARTTLS in the EHLO answer to everyone:
467 \begin{lstlisting}[breaklines]
468 tls_advertise_hosts = *
471 Listen on smtp(25) port only
472 \begin{lstlisting}[breaklines]
473 daemon_smtp_ports = smtp
476 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.\\
477 % Exim maintainers do not recommend to change default ciphers
480 %\begin{lstlisting}[breaklines]
481 % tls_require_ciphers = <...recommended ciphersuite...>
484 If you want to request and verify client certificates from sending hosts set
485 \begin{lstlisting}[breaklines]
486 tls_verify_certificates = /etc/pki/tls/certs/ca-bundle.crt
487 tls_try_verify_hosts = *
490 tls\_try\_verify\_hosts only reports the result to your logfile. If you want to disconnect such clients you have to use
491 \begin{lstlisting}[breaklines]
495 The cipher used is written to the logfiles by default. You may want to add
496 \begin{lstlisting}[breaklines]
497 log_selector = <....whatever your log_selector already contains...> \
498 +tls_certificate_verified +tls_peerdn +tls_sni
500 to get even more TLS information logged.
502 \paragraph*{client mode (outgoing)}\mbox{}\\
504 Exim uses opportunistic encryption in the SMTP transport by default.
506 Client mode settings have to be done in the configuration section of the smtp transport (driver = smtp).
508 If you want to use a client certificate (most server certificates can be used as client certificate, too) set
509 \begin{lstlisting}[breaklines]
510 tls_certificate = .../cert.pem
511 tls_privatekey = .../cert.key
513 This is recommended for MTA-MTA traffic.\\
515 %If you want to limit used ciphers set
516 %\begin{lstlisting}[breaklines]
517 % tls_require_ciphers = <...recommended ciphersuite...>
519 % Exim Maintainers do not recommend ciphers. We shouldn't do so, too.
520 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.
522 \paragraph*{OpenSSL}\mbox{}\\
523 Exim already disables SSLv2 by default. We recommend to add
524 \begin{lstlisting}[breaklines]
525 openssl_options = +all +no_sslv2 +no_compression +cipher_server_preference
527 to the main configuration.\\
528 Note: +all is misleading here since OpenSSL only activates the most common workarounds. But that's how SSL\_OP\_ALL is defined.\\
530 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).
531 If you want to set your own DH parameters please read the TLS documentation of exim.\\
535 \paragraph*{GnuTLS}\mbox{}\\
537 GnuTLS is different in only some respects to OpenSSL:
539 \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.
540 \item There is no option like openssl\_options
543 \paragraph*{Exim string expansion}\mbox{}\\
545 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.
547 \paragraph*{Limitations}\mbox{}\\
549 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.
550 There already is a working patch to provide support:\\
551 \url{http://bugs.exim.org/show_bug.cgi?id=1397}
554 % do we need to documment starttls in detail?
555 %\subsubsection{starttls?}
559 \begin{lstlisting}[breaklines]
561 PermitEmptyPasswords no
564 HostKey /etc/ssh/ssh_host_rsa_key
566 MACs hmac-sha2-512,hmac-sha2-256,hmac-ripemd160
567 KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
570 % XXX: curve25519-sha256@libssh.org only available upstream(!)
571 Note: older linux systems won't support SHA2, PuTTY does not support RIPE-MD160.
576 \todo{write this subsection}
577 \subsubsection{IPSec}
579 \todo{cm: check if there are downgrade attacks for checkpoint \& co} \\
580 \todo{cm: reference the paper describing how complex IPSec is and that it can't be checked properly} \\
581 \todo{cm: change this to a table format: Variant ((A,B), (recommendations, recommendations))} \\
583 \paragraph*{Assumptions}\mbox{}\\
585 We assume the usage of IKE (v1 or v2) for this document, and ESP.
587 \paragraph*{Authentication}\mbox{}\\
589 IPSEC authentication should optimally be performed via RSA signatures,
590 with a key size of 2048 bits or more. Configuring only the trusted CA
591 that issued the peer certificate provides for additional protection
592 against fake certificates.
594 If you need to use Pre-Shared Key authentication:
597 \item Choose a \textbf{random} PSK of 20 characters or more (\todo{length, references!})
598 \item Use a \textbf{separate} PSK for any IPSEC connection
599 \item Change the PSKs regularily
602 \paragraph*{Cryptographic Suites}\mbox{}\\
604 IPSEC Cryptographic Suites are pre-defined settings for all the
605 items of a configuration; they try to provide a balanced security
606 level and make setting up VPNs easier.
608 When using any of those suites, make sure to enable ``Perfect Forward
609 Secrecy`` for Phase 2, as this is not specified in the suites.
611 \verb|Suite-B-GCM-256| \footnote{\url{http://tools.ietf.org/html/rfc6379}}
612 would be roughly equivalent to ``Configuration A``, but keep in mind
613 that it uses NIST elliptic curves for the Diffie-Hellman key exchange.
615 \verb|Suite-B-GCM-128| or
616 \verb|VPN-B| \footnote{\url{http://tools.ietf.org/html/rfc4308}} would
617 be roughly equivalent to ``Configuration B``; again,
618 \verb|Suite-B-GCM-128| uses NIST elliptic curves, \verb|VPN-B| does
621 \todo{Aaron: make an example for how to include images}
622 \todo{cm: screenshots of Checkpoint settings}
624 \paragraph*{IKE or Phase 1}\mbox{}\\
626 IKE or Phase 1 is the mutual authentication and key exchange phase.
628 Use only ``main mode``, as ``aggressive mode`` has known security
629 vulnerabilities \footnote{\url{http://ikecrack.sourceforge.net/}}.
631 Encryption Algorithm: AES or CAMELLIA
633 Hash Algorithm: SHA2-256, SHA2-384 or SHA2-512
635 DH Group: Group 14--18 (2048--8192 bit DH), or 19-21 (256--521 bit
638 Lifetime: \todo{need recommendations; 1 day seems to be common practice}
640 \todo{what about CAST?}
642 \paragraph*{ESP or Phase 2}\mbox{}\\
644 Enable ``Perfect Forward Secrecy`` with a DH Group equivalent to the
647 Encryption Algorithm: AES-GCM-16, AES-CTR, AES-CCM-16, AES-CBC, SEED
648 or CAMELLIA \todo{order of this list?}
650 Hash Algorithm: none (if using AES-GCM), HMAC-SHA-SHA256 or longer
651 \todo{what about AES-XCBC-MAC?}
653 Lifetime: \todo{need recommendations; 1--8 hours seems to be common practice}
656 \subsubsection{OpenVPN}
657 \todo{cm: please write this subsubsection}
658 \todo{WARNING - Section Writing in progress...}
659 \todo{We suppose user uses easy-rsa which is roughly used in all HOWTO}
661 \paragraph{Fine tuning at installation level}
663 When installing an OpenVPN server instance, you are probably using {\it easy-rsa} tools to generate the crypto stuff needed.
664 From the directory where you will run them, you can enhance you configuration by changing the following variables in {\it Vars}
666 \begin{lstlisting}[breaklines]
670 This will enhance the security of the key exchange steps by using RSA keys with a length of 2048 bits.
672 \todo{Shouldn't we need to reduce CA and certificate lifetime? Per default 10y!!}
675 \paragraph{Server Configuration}
677 \todo{To write - locked by David}
679 \begin{lstlisting}[breaklines]
680 cipher AES-128-CBC # AES
684 \paragraph{Client Configuration}
686 \todo{To write - locked by David}
688 \begin{lstlisting}[breaklines]
695 \todo{cm: please write this subsubsection}
697 \subsubsection{Cisco IPSec}
698 \todo{write this subsubsection}
700 \subsubsection{Juniper VPN}
701 \todo{write this subsubsection. AK: ask Hannes}
703 \subsubsection{L2TP over IPSec}
704 \todo{write this subsubsection}
706 \subsubsection{Racoon}
707 \todo{write this subsubsection}
710 \subsection{PGP/ GPG - Pretty Good Privacy}
712 \todo{re-work this subsection -- this is still only a draft!!}
715 \subsection{seclayer-tcp}
716 \todo{Ramin: please write this section or ask Posch}
717 For the austrian citizen card....
720 seclayer-tcp 3495/udp # securitylayer over tcp
721 seclayer-tcp 3495/tcp # securitylayer over tcp
725 \subsection{IPMI, ILO and other lights out management solutions}
726 \todo{write this!! Recommendation. Empfehlung: nie ins Internet, nur in ein eigenes mgmt VLAN, das via VPN erreichbar ist!!
730 \todo{AK: ask Klaus. Write this section, Klaus??? }
732 \subsection{Instant Messaging Systems}
733 \subsubsection{XMPP / Jabber}
734 \todo{ts: Describe ejabberd configuration. Reference to Peter`s manifesto https://github.com/stpeter/manifesto}
739 \input{proxy_solutions}
745 %%% TeX-master: "applied-crypto-hardening"