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 and POP/IMAP Servers}
189 This section documents the most common mail 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 \subsubsection{Postfix}
312 First, you need to generate Diffie Hellman parameters (please first take a look at the section \ref{section:PRNG}):
314 \todo{FIXME: this is a really weak setting! See also: http://postfix.1071664.n5.nabble.com/postfix-hardening-what-can-we-do-td61874.html}
315 \begin{lstlisting}[breaklines]
316 % openssl gendh -out /etc/postfix/dh_param_512.pem -2 512
317 % openssl gendh -out /etc/postfix/dh_param_1024.pem -2 1024
320 Next, we specify these DH parameters in the postfix config file:
322 \begin{lstlisting}[breaklines]
323 smtpd_tls_dh512_param_file = /etc/postfix/dh_param_512.pem
324 smtpd_tls_dh1024_param_file = /etc/postfix/dh_param_1024.pem
327 You usually don't want restrictions on the ciphers for opportunistic
328 encryption, because any encryption is better than plain text.
330 For submission (Port 587) or other special cases, however, you want to
331 enforce strong encryption. In addition to the below entries in
332 main.cf, you need to enable ``mandatory`` encryption for the
333 respective service, e.g. by adding ``-o
334 smtpd\_tls\_security\_level=encrypt'' to the submission smtpd in
337 % don't -- this influences opportunistic encryption
338 % smtpd_tls_protocols = !SSLv2, !SSLv3
340 \begin{lstlisting}[breaklines]
341 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
342 tls_ssl_options=NO_COMPRESSION
343 smtpd_tls_mandatory_ciphers=high
344 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'
345 tls_preempt_cipherlist = yes
346 tls_random_source = dev:/dev/urandom
347 %% NOTE: might want to have /dev/random here + Haveged
350 For those users, who want to use ECC key exchange, it is possible to specify this via:
351 \begin{lstlisting}[breaklines]
352 smtpd_tls_eecdh_grade = ultra
355 You can check the settings by specifying smtpd\_tls\_loglevel = 1 and then check the selected ciphers with the following command:
356 \begin{lstlisting}[breaklines]
357 $ zegrep "TLS connection established from.*with cipher" /var/log/mail.log | \
358 > awk '{printf("%s %s %s %s\n", $12, $13, $14, $15)}' | sort | uniq -c | sort -n
359 1 SSLv3 with cipher DHE-RSA-AES256-SHA
360 23 TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384
361 60 TLSv1 with cipher ECDHE-RSA-AES256-SHA
362 270 TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384
363 335 TLSv1 with cipher DHE-RSA-AES256-SHA
366 To use outgoing opportunistic TLS in postfix
368 \begin{lstlisting}[breaklines]
369 smtp_tls_note_starttls_offer = yes¬
370 smtp_tls_security_level = may¬
374 Source: \url{http://www.postfix.org/TLS_README.html}
376 \paragraph*{Limitations}\mbox{}\\
378 tls\_ssl\_options is supported from Postfix 2.11 onwards. You can
379 leave the statement in the configuration for older versions, it will
382 tls\_preempt\_cipherlist is supported from Postfix 2.8 onwards. Again,
383 you can leave the statement in for older versions.
386 \subsubsection{Exim (based on 4.82)}
388 It is highly recommended to read
390 \url{http://exim.org/exim-html-current/doc/html/spec_html/ch-encrypted_smtp_connections_using_tlsssl.html}
396 \subparagraph*{server mode (incoming)}\mbox{}\\
398 In the main config section of exim add:
400 \begin{lstlisting}[breaklines]
401 tls_certificate = ..../cert.pem
402 tls_privatekey = ..../cert.key
404 don't forget to add intermediate certificates to the .pem file if needed.\\
406 Tell exim to advertise STARTTLS in the EHLO answer:
407 \begin{lstlisting}[breaklines]
408 tls_advertise_hosts = *
411 If you want to support legacy SMTPS on port 465, and STARTTLS on smtp(25)/submission(587) ports set
412 \begin{lstlisting}[breaklines]
413 daemon_smtp_ports = smtp : smtps : submission
414 tls_on_connect_ports = 465
417 Exim already disables SSLv2 by default. We recommend to add
418 \begin{lstlisting}[breaklines]
419 openssl_options = +no_sslv2 +no_compression +cipher_server_preference
422 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.\\
423 % Exim maintainers do not recommend to change default ciphers
426 %\begin{lstlisting}[breaklines]
427 % tls_require_ciphers = <...recommended ciphersuite...>
430 If you want to request and verify client certificates from sending hosts set
431 \begin{lstlisting}[breaklines]
432 tls_verify_certificates = /etc/pki/tls/certs/ca-bundle.crt
433 tls_try_verify_hosts = *
436 tls\_try\_verify\_hosts only reports the result to your logfile. If you want to disconnect such clients you have to use
437 \begin{lstlisting}[breaklines]
441 You do not need to set dh\_parameters. exim with OpenSSL uses a 2048bit default prime defined in section 2.2 of RFC 5114.
442 If you want to set your own DH parameters please read the TLS documentation of exim.\\
444 The cipher used is written to the logfiles by default. You may want to add
445 \begin{lstlisting}[breaklines]
446 log_selector = <....whatever your log_selector already contains...> \
447 +tls_certificate_verified +tls_peerdn +tls_sni
449 to get even more information logged.
451 \subparagraph*{client mode (outgoing)}\mbox{}\\
453 Exim uses opportunistic encryption in the SMTP transport by default.
455 Client mode settings have to be done in the configuration section of the smtp transport (driver = smtp).
457 If you want to use a client certificate (most server certificates can be used as client certificate, too) set
458 \begin{lstlisting}[breaklines]
459 tls_certificate = .../cert.pem
460 tls_privatekey = .../cert.key
462 This is recommended for MTA-MTA traffic.\\
464 %If you want to limit used ciphers set
465 %\begin{lstlisting}[breaklines]
466 % tls_require_ciphers = <...recommended ciphersuite...>
468 % Exim Maintainers do not recommend ciphers. We shouldn't do so, too.
469 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.
471 \paragraph*{GnuTLS}\mbox{}\\
473 GnuTLS is different in only some respects to OpenSSL:
475 \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.
476 \item There is no option like openssl\_options
479 \paragraph*{Limit SMTP AUTH to SSL connections only}\mbox{}\\
481 It is highly recommended to limit SMTP AUTH to SSL connections only. To do so add
482 \begin{lstlisting}[breaklines]
483 server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}}
485 to every authenticator defined.
487 \paragraph*{Exim string expansion}\mbox{}\\
489 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.
491 \paragraph*{Limitations}\mbox{}\\
493 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.
494 There already is a working patch to provide support:\\
495 \url{http://bugs.exim.org/show_bug.cgi?id=1397}
498 % do we need to documment starttls in detail?
499 %\subsubsection{starttls?}
503 \begin{lstlisting}[breaklines]
505 PermitEmptyPasswords no
508 HostKey /etc/ssh/ssh_host_rsa_key
510 MACs hmac-sha2-512,hmac-sha2-256,hmac-ripemd160
511 KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
514 % XXX: curve25519-sha256@libssh.org only available upstream(!)
515 Note: older linux systems won't support SHA2, PuTTY does not support RIPE-MD160.
520 \todo{write this subsection}
521 \subsubsection{IPSec}
523 \todo{cm: check if there are downgrade attacks for checkpoint \& co} \\
524 \todo{cm: reference the paper describing how complex IPSec is and that it can't be checked properly} \\
525 \todo{cm: change this to a table format: Variant ((A,B), (recommendations, recommendations))} \\
527 \paragraph*{Assumptions}\mbox{}\\
529 We assume the usage of IKE (v1 or v2) for this document, and ESP.
531 \paragraph*{Authentication}\mbox{}\\
533 IPSEC authentication should optimally be performed via RSA signatures,
534 with a key size of 2048 bits or more. Configuring only the trusted CA
535 that issued the peer certificate provides for additional protection
536 against fake certificates.
538 If you need to use Pre-Shared Key authentication:
541 \item Choose a \textbf{random} PSK of 20 characters or more (\todo{length, references!})
542 \item Use a \textbf{separate} PSK for any IPSEC connection
543 \item Change the PSKs regularily
546 \paragraph*{Cryptographic Suites}\mbox{}\\
548 IPSEC Cryptographic Suites are pre-defined settings for all the
549 items of a configuration; they try to provide a balanced security
550 level and make setting up VPNs easier.
552 When using any of those suites, make sure to enable ``Perfect Forward
553 Secrecy`` for Phase 2, as this is not specified in the suites.
555 \verb|Suite-B-GCM-256| \footnote{\url{http://tools.ietf.org/html/rfc6379}}
556 would be roughly equivalent to ``Configuration A``, but keep in mind
557 that it uses NIST elliptic curves for the Diffie-Hellman key exchange.
559 \verb|Suite-B-GCM-128| or
560 \verb|VPN-B| \footnote{\url{http://tools.ietf.org/html/rfc4308}} would
561 be roughly equivalent to ``Configuration B``; again,
562 \verb|Suite-B-GCM-128| uses NIST elliptic curves, \verb|VPN-B| does
565 \todo{Aaron: make an example for how to include images}
566 \todo{cm: screenshots of Checkpoint settings}
568 \paragraph*{IKE or Phase 1}\mbox{}\\
570 IKE or Phase 1 is the mutual authentication and key exchange phase.
572 Use only ``main mode``, as ``aggressive mode`` has known security
573 vulnerabilities \footnote{\url{http://ikecrack.sourceforge.net/}}.
575 Encryption Algorithm: AES or CAMELLIA
577 Hash Algorithm: SHA2-256, SHA2-384 or SHA2-512
579 DH Group: Group 14--18 (2048--8192 bit DH), or 19-21 (256--521 bit
582 Lifetime: \todo{need recommendations; 1 day seems to be common practice}
584 \todo{what about CAST?}
586 \paragraph*{ESP or Phase 2}\mbox{}\\
588 Enable ``Perfect Forward Secrecy`` with a DH Group equivalent to the
591 Encryption Algorithm: AES-GCM-16, AES-CTR, AES-CCM-16, AES-CBC, SEED
592 or CAMELLIA \todo{order of this list?}
594 Hash Algorithm: none (if using AES-GCM), HMAC-SHA-SHA256 or longer
595 \todo{what about AES-XCBC-MAC?}
597 Lifetime: \todo{need recommendations; 1--8 hours seems to be common practice}
600 \subsubsection{OpenVPN}
601 \todo{cm: please write this subsubsection}
602 \todo{WARNING - Section Writing in progress...}
603 \todo{We suppose user uses easy-rsa which is roughly used in all HOWTO}
605 \paragraph{Fine tuning at installation level}
607 When installing an OpenVPN server instance, you are probably using {\it easy-rsa} tools to generate the crypto stuff needed.
608 From the directory where you will run them, you can enhance you configuration by changing the following variables in {\it Vars}
610 \begin{lstlisting}[breaklines]
614 This will enhance the security of the key exchange steps by using RSA keys with a length of 2048 bits.
616 \todo{Shouldn't we need to reduce CA and certificate lifetime? Per default 10y!!}
619 \paragraph{Server Configuration}
621 \todo{To write - locked by David}
623 \begin{lstlisting}[breaklines]
624 cipher AES-128-CBC # AES
628 \paragraph{Client Configuration}
630 \todo{To write - locked by David}
632 \begin{lstlisting}[breaklines]
639 \todo{cm: please write this subsubsection}
641 \subsubsection{Cisco IPSec}
642 \todo{write this subsubsection}
644 \subsubsection{Juniper VPN}
645 \todo{write this subsubsection. AK: ask Hannes}
647 \subsubsection{L2TP over IPSec}
648 \todo{write this subsubsection}
650 \subsubsection{Racoon}
651 \todo{write this subsubsection}
654 \subsection{PGP/ GPG - Pretty Good Privacy}
656 \todo{re-work this subsection -- this is still only a draft!!}
659 \subsection{seclayer-tcp}
660 \todo{Ramin: please write this section or ask Posch}
661 For the austrian citizen card....
664 seclayer-tcp 3495/udp # securitylayer over tcp
665 seclayer-tcp 3495/tcp # securitylayer over tcp
669 \subsection{IPMI, ILO and other lights out management solutions}
670 \todo{write this!! Recommendation. Empfehlung: nie ins Internet, nur in ein eigenes mgmt VLAN, das via VPN erreichbar ist!!
674 \todo{AK: ask Klaus. Write this section, Klaus??? }
676 \subsection{Instant Messaging Systems}
677 \subsubsection{XMPP / Jabber}
680 %\subsection{Database Systems}
681 %\subsubsection{MySQL}
683 %\paragraph*{my.cnf}\mbox{}\\
685 %%Tested with Debian 7.0 and MySQL 5.5
687 %\begin{lstlisting}[breaklines]
690 %ssl-ca=/etc/mysql/ssl/ca-cert.pem
691 %ssl-cert=/etc/mysql/ssl/client-cert.pem
692 %ssl-key=/etc/mysql/ssl/client-key.pem
693 %ssl-cipher=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
696 %After restarting the server run the following query to see if the ssl settings are correct:
697 %\begin{lstlisting}[breaklines]
698 %show variables like '%ssl%';
705 %%% TeX-master: "applied-crypto-hardening"