查看当前版本：
gnutls-cli -v
卸载低版本：
如果有通过yum/rpm安装的gnutls，需要先卸载：
rpm -e --nodeps gnutls
rpm -e --nodeps gnutls-devel
通过源码包编译安装：
最新版本：GnuTLS 3.5.11 (2017-04-7)
实证通过：GnuTLS 3.5.11
官网：http://gnutls.org/
下载：http://gnutls.org/download.html
参考：http://gnutls.org/manual/gnutls.html
参考：http://linuxfromscratch.org/blfs/view/svn/postlfs/gnutls.html (GnuTLS-3.5.11)
安装nettle：https://amon.org/nettle
安装p11-kit：https://amon.org/p11-kit
安装libasn1：https://amon.org/libtasn1
安装libgmp：https://amon.org/gmplib
wget ftp://ftp.gnutls.org/gcrypt/gnutls/v3.5/gnutls-3.5.11.tar.xz && xz -d gnutls-3.5.11.tar.xz && tar -xvf gnutls-3.5.11.tar && cd gnutls-3.5.11
export NETTLE_CFLAGS="-I/usr/include/nettle" NETTLE_LIBS="-L/usr/lib64 -lnettle" HOGWEED_CFLAGS="-I/usr/include/nettle" HOGWEED_LIBS="-L/usr/lib64 -lhogweed" P11_KIT_CFLAGS="-I/usr/include/p11-kit-1/p11-kit" P11_KIT_LIBS="-L/usr/lib -lp11-kit" LIBTASN1_CFLAGS="-I/usr/include" LIBTASN1_LIBS="-L/usr/lib -ltasn1" GMP_CFLAGS="-I/usr/local/include" GMP_LIBS="-L/usr/local/lib -lgmp"
./configure --prefix=/usr --with-default-trust-store-file=/etc/ssl/ca-bundle.crt --enable-gtk-doc --enable-openssl-compatibility --enable-local-libopts --with-included-unistring
配置信息：
configure: summary of build options:
version: 3.5.11 shared 44:2:14
Host/Target system: x86_64-pc-linux-gnu
Build system: x86_64-pc-linux-gnu
Install prefix: /usr
Compiler: gcc -std=gnu99
Valgrind: no
CFlags: -g -O2
Library types: Shared=yes, Static=no
Local libopts: yes
Local libtasn1: no
Local unistring: yes
Use nettle-mini: no
Documentation: yes (manpages: yes)
configure: External hardware support:
/dev/crypto: no
Hardware accel: x86-64
Padlock accel: yes
Random gen. variant: auto-detect
PKCS#11 support: yes
TPM support: yes
configure:
TPM library: /usr/lib64/libtspi.so.1
configure: Optional features:
(note that included applications might not compile properly
if features are disabled)
SSL3.0 support: yes
SSL2.0 client hello: yes
DTLS-SRTP support: yes
ALPN support: yes
OCSP support: yes
Ses. ticket support: yes
OpenPGP support: yes
SRP support: yes
PSK support: yes
DHE support: yes
ECDHE support: yes
Anon auth support: yes
Heartbeat support: yes
IDNA support: IDNA 2003 (libidn)
Self checks: no
Non-SuiteB curves: yes
FIPS140 mode: no
configure: Optional libraries:
Guile wrappers: yes
C++ library: yes
DANE library: yes
OpenSSL compat: yes
configure: System files:
Trust store pkcs11:
Trust store dir:
Trust store file: /etc/ssl/ca-bundle.crt
Blacklist file:
CRL file:
Priority file: /etc/gnutls/default-priorities
DNSSEC root key file: /var/lib/unbound/root.key
然后make：
make
报错：
./../pkcs11_int.h:27:28: fatal error: p11-kit/pkcs11.h: No such file or directory
#include <p11-kit/pkcs11.h>
没找到文件，那就复制过来：
cp -R /usr/include/p11-kit-1/p11-kit /root/gnutls-3.5.11/lib/p11-kit
重新 make 通过，继续 make install ：
make install
输出：
...
Libraries have been installed in:
/usr/lib
...
Libraries have been installed in:
/usr/lib/guile/2.0
...
make[1]: Leaving directory `/root/sni/gnutls-3.5.8'
更新系统动态连接库配置：
echo /usr/lib >> /etc/ld.so.conf && ldconfig
编译安装完成。
相关路径：
/usr/include/gnutls/gnutls.h
/usr/lib/libgnutls.so.30.8.1
注意：需要重新编译mod_gnutls才能在Apache中使新版本生效。
参考：https://amon.org/mod_gnutls
查看版本
查看版本（shell）：
gnutls-cli -v
输出：
gnutls-cli 3.5.11
Copyright (C) 2000-2017 Free Software Foundation, and others, all rights reserved.
This is free software. It is licensed for use, modification and
redistribution under the terms of the GNU General Public License,
version 3 or later <http://gnu.org/licenses/gpl.html>
Please send bug reports to: <bugs@gnutls.org>
报错：p11_kit_uri_get_pin_value
../lib/.libs/libgnutls.so: undefined reference to `p11_kit_uri_get_pin_value'
You are compiling with a newer library than the one you are linking with.
Most likely you have both versions of the libraries available but your
flags to linker are not correct.
因为系统中存在2个版本的p11-kit，而并不支持高版本gnutls的低版本p11-kit被使用。所以，需要移除低版本，然后编译安装高版本p11-kit。
参考：https://amon.org/p11-kit
报错：sys_getrandom
在make时报错，探讨解决办法：https://amon.org/sys_getrandom ，暂无解决办法。
git方式编译安装：
实证未遂。
下载：https://gitlab.com/gnutls/gnutls
安装依赖包：
yum install git autoconf libtool automake autogen autogen-libopts-devel trousers-devel guile-devel libidn-devel gawk gperf git2cl libtasn1-tools unbound-devel help2man gtk-doc texinfo texlive valgrind libasan libasan-static libubsan nodejs softhsm datefudge lcov dieharder mbedtls-utils abi-compliance-checker libcmocka-devel socat
开始编译：
git clone https://gitlab.com/gnutls/gnutls.git && cd gnutls
git submodule update --init
autoreconf -i && automake && autoconf
export NETTLE_CFLAGS="-I/usr/include/nettle" NETTLE_LIBS="-L/usr/lib64 -lnettle" HOGWEED_CFLAGS="-I/usr/include/nettle" HOGWEED_LIBS="-L/usr/lib64 -lhogweed" P11_KIT_CFLAGS="-I/usr/include/p11-kit-1/p11-kit" P11_KIT_LIBS="-L/usr/lib -lp11-kit" LIBTASN1_CFLAGS="-I/usr/include" LIBTASN1_LIBS="-L/usr/lib -ltasn1" GMP_CFLAGS="-I/usr/local/include" GMP_LIBS="-L/usr/local/lib -lgmp"
./configure --prefix=/usr --with-default-trust-store-file=/etc/ssl/ca-bundle.crt --enable-gtk-doc --enable-openssl-compatibility --enable-local-libopts
make bootstrap
make
make check
make install
报错：asn1_der_decoding2
In file included from common.c:34:0:
./common.h: In function '_asn1_strict_der_decode':
./common.h:259:2: warning: implicit declaration of function 'asn1_der_decoding2' [-Wimplicit-function-declaration]
重新编译libtasn1。
参考：https://amon.org/libtasn1
报错：sha256_ctx
struct sha256_ctx' has no member named 'count'
参考：https://dev.openwrt.org/changeset/41263
重新编译nettle。
参考：https://amon.org/nettle
报错：pkcs11_int.h
./../pkcs11_int.h:27:28: fatal error: p11-kit/pkcs11.h: No such file or directory
#include <p11-kit/pkcs11.h>
缺少还是没找到，那就复制过来：
cp -R /usr/include/p11-kit-1/p11-kit /root/gnutls/lib/p11-kit
事实证明这种方案可行。
参考：http://www.gnutls.org/manual/html_node/gnutls_002dcli-Invocation.html
参考资料：
参考：https://www.painso.com/ocserv-install-usage
参考：http://zkxtom365.blogspot.com/2015/02/centos-65ocservcisco-anyconnect
参考：http://blog.csdn.net/tanogut/article/details/7836545
参考：http://www.cnblogs.com/siikee/p/4272104
参考：http://lists.gnutls.org/pipermail/gnutls-help/2013-May/003136
参考：http://linux.debian.bugs.rc.narkive.com/9Z5rQcJT/bug-782078-info-received-additional-info-probably-caused-by-evolution-mapi
参考：https://github.com/rdp/ffmpeg-windows-build-helpers/issues/513573192551
