现在市面上有很多免费的SSL证书可供申请。但是基本上不支持针对仅IP提供SSL证书，这里可以利用自签的方法来为仅使用IP的网站开启https.
生成根密钥和根证书。
#生成根密钥 openssl genrsa -out cakey.pem 2048
#生成根证书并使用根密钥对根证书签名 openssl req -new -x509 -key cakey.pem -out cacert.pem #这里会提示输入一些内容，可以随便输入，但是最好能够记住与之后保持一致，否则可能导致使用根证书签名服务器证书的时候出现错误，如果出现错误可以修改openssl的配置文件来解决。
生成服务器密钥和证书
这里在需要使用SSL的服务器上进行操作。
#生成服务器密钥 openssl genrsa -out server.key 2048
#生成服务器证书签署请求。 openssl req -new -key server.key -out server.csr #这里会要求输入一些内容，Commone Name为你需要使用SSL的域名或IP。challenge password不填。
使用自有的根证书签署服务器证书。
将server.csr发送的根证书的机器上。
可以用使用cat命令，复制其中的文本内容，然后在根证书的机器上使用vi命令创建文件并粘贴刚刚复制的内容.
openssl x509 -req -sha256 -in server.csr -extensions v3_req -CA cacert.pem -CAkey cakey.pem -CAcreateserial -out server.crt -days 365
同样可以使用cat命令复制文本内容，并在需要使用SSL证书的机器上使用vi命令创建文件并粘贴刚刚复制的内容。
使用ssl证书
我使用的lnmp.org的一键环境，在此环境下可以使用lnmp ssl命令来简单的添加ssl证书。
lnmp ssl
添加多域名
在有的时候需要在一个证书上添加多个域名，这个时候可以修改openssl.cnf文件。
主要修改在openssl.cnf # 确保req下存在以下2行（默认第一行是有的，第2行被注释了） [ req ] distinguished_name = req_distinguished_name req_extensions = v3_req # 确保req_distinguished_name下没有 0.xxx 的标签，有的话把0.xxx的0. 去掉 [ req_distinguished_name ] countryName = Country Name (2 letter code) countryName_default = CN stateOrProvinceName = State or Province Name (full name) stateOrProvinceName_default = ShangHai localityName = Locality Name (eg, city) localityName_default = ShangHai organizationalUnitName = Organizational Unit Name (eg, section) organizationalUnitName_default = Domain Control Validated commonName = Internet Widgits Ltd commonName_max = 64 # 新增最后一行内容 subjectAltName = @alt_names（前2行默认存在） [ v3_req ] # Extensions to add to a certificate request basicConstraints = CA:FALSE keyUsage = nonRepudiation, digitalSignature, keyEncipherment subjectAltName = @alt_names # 新增 alt_names,注意括号前后的空格，DNS.x 的数量可以自己加 [ alt_names ] DNS.1 = abc.example.com DNS.2 = dfe.example.org DNS.3 = ex.abcexpale.net
其他的步骤：
openssl.cnf中会要求部分文件及目录存在：
[root@localhost]#mkdir -p CA/{certs,crl,newcerts,private}
[root@localhost]# touch CA/index.txt
[root@localhost]#echo 00 > CA/serial
如果没有openssl.cnf文件 可以自己创建一个，这里分享一个文件。
#
# OpenSSL example configuration file.
# This is mostly being used for generation of certificate requests.
#
# This definition stops the following lines choking if HOME isn't
# defined.
HOME = .
RANDFILE = $ENV::HOME/.rnd
# Extra OBJECT IDENTIFIER info:
#oid_file = $ENV::HOME/.oid
oid_section = new_oids
# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions =
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)
[ new_oids ]
# We can add new OIDs in here for use by 'ca', 'req' and 'ts'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6
# Policies used by the TSA examples.
tsa_policy1 = 1.2.3.4.1
tsa_policy2 = 1.2.3.4.5.6
tsa_policy3 = 1.2.3.4.5.7
####################################################################
[ ca ]
default_ca = CA_default # The default ca section
####################################################################
[ CA_default ]
dir = ./demoCA # Where everything is kept
certs = $dir/certs # Where the issued certs are kept
crl_dir = $dir/crl # Where the issued crl are kept
database = $dir/index.txt # database index file.
#unique_subject = no # Set to 'no' to allow creation of
# several ctificates with same subject.
new_certs_dir = $dir/newcerts # default place for new certs.
certificate = $dir/cacert.pem # The CA certificate
serial = $dir/serial # The current serial number
crlnumber = $dir/crlnumber # the current crl number
# must be commented out to leave a V1 CRL
crl = $dir/crl.pem # The current CRL
private_key = $dir/private/cakey.pem# The private key
RANDFILE = $dir/private/.rand # private random number file
x509_extensions = usr_cert # The extentions to add to the cert
# Comment out the following two lines for the "traditional"
# (and highly broken) format.
name_opt = ca_default # Subject Name options
cert_opt = ca_default # Certificate field options
# Extension copying option: use with caution.
# copy_extensions = copy
# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crlnumber must also be commented out to leave a V1 CRL.
# crl_extensions = crl_ext
default_days = 365 # how long to certify for
default_crl_days= 30 # how long before next CRL
default_md = default # use public key default MD
preserve = no # keep passed DN ordering
# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy = policy_match
# For the CA policy
[ policy_match ]
countryName = optional
stateOrProvinceName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
####################################################################
[ req ]
default_bits = 2048
default_keyfile = privkey.pem
distinguished_name = req_distinguished_name
attributes = req_attributes
x509_extensions = v3_ca # The extentions to add to the self signed cert
# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret
# This sets a mask for permitted string types. There are several options.
# default: PrintableString, T61String, BMPString.
# pkix : PrintableString, BMPString (PKIX recommendation before 2004)
# utf8only: only UTF8Strings (PKIX recommendation after 2004).
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
# WARNING: ancient versions of Netscape crash on BMPStrings or UTF8Strings.
string_mask = utf8only
req_extensions = v3_req # The extensions to add to a certificate request
[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = AU
countryName_min = 2
countryName_max = 2
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = Some-State
localityName = Locality Name (eg, city)
0.organizationName = Organization Name (eg, company)
0.organizationName_default = Internet Widgits Pty Ltd
# we can do this but it is not needed normally :-)
#1.organizationName = Second Organization Name (eg, company)
#1.organizationName_default = World Wide Web Pty Ltd
organizationalUnitName = Organizational Unit Name (eg, section)
#organizationalUnitName_default =
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_max = 64
emailAddress = Email Address
emailAddress_max = 64
# SET-ex3 = SET extension number 3
[ req_attributes ]
challengePassword = A challenge password
challengePassword_min = 4
challengePassword_max = 20
unstructuredName = An optional company name
[ usr_cert ]
# These extensions are added when 'ca' signs a request.
# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.
basicConstraints=CA:FALSE
# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.
# This is OK for an SSL server.
# nsCertType = server
# For an object signing certificate this would be used.
# nsCertType = objsign
# For normal client use this is typical
# nsCertType = client, email
# and for everything including object signing:
# nsCertType = client, email, objsign
# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment
# This will be displayed in Netscape's comment listbox.
nsComment = "OpenSSL Generated Certificate"
# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move
# Copy subject details
# issuerAltName=issuer:copy
#nsCaRevocationUrl = http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName
# This is required for TSA certificates.
# extendedKeyUsage = critical,timeStamping
[ v3_req ]
# Extensions to add to a certificate request
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
[ v3_ca ]
# Extensions for a typical CA
# PKIX recommendation.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer
# This is what PKIX recommends but some broken software chokes on critical
# extensions.
#basicConstraints = critical,CA:true
# So we do this instead.
basicConstraints = CA:true
# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign
# Some might want this also
# nsCertType = sslCA, emailCA
# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy
# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF
[ crl_ext ]
# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.
# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always
[ proxy_cert_ext ]
# These extensions should be added when creating a proxy certificate
# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.
basicConstraints=CA:FALSE
# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.
# This is OK for an SSL server.
# nsCertType = server
# For an object signing certificate this would be used.
# nsCertType = objsign
# For normal client use this is typical
# nsCertType = client, email
# and for everything including object signing:
# nsCertType = client, email, objsign
# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment
# This will be displayed in Netscape's comment listbox.
nsComment = "OpenSSL Generated Certificate"
# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move
# Copy subject details
# issuerAltName=issuer:copy
#nsCaRevocationUrl = http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName
# This really needs to be in place for it to be a proxy certificate.
proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo
####################################################################
[ tsa ]
default_tsa = tsa_config1 # the default TSA section
[ tsa_config1 ]
# These are used by the TSA reply generation only.
dir = ./demoCA # TSA root directory
serial = $dir/tsaserial # The current serial number (mandatory)
crypto_device = builtin # OpenSSL engine to use for signing
signer_cert = $dir/tsacert.pem # The TSA signing certificate
# (optional)
certs = $dir/cacert.pem # Certificate chain to include in reply
# (optional)
signer_key = $dir/private/tsakey.pem # The TSA private key (optional)
default_policy = tsa_policy1 # Policy if request did not specify it
# (optional)
other_policies = tsa_policy2, tsa_policy3 # acceptable policies (optional)
digests = md5, sha1 # Acceptable message digests (mandatory)
accuracy = secs:1, millisecs:500, microsecs:100 # (optional)
clock_precision_digits = 0 # number of digits after dot. (optional)
ordering = yes # Is ordering defined for timestamps?
# (optional, default: no)
tsa_name = yes # Must the TSA name be included in the reply?
# (optional, default: no)
ess_cert_id_chain = no # Must the ESS cert id chain be included?
# (optional, default: no)
在签名的时候将openssl包含进去就可以了。
openssl x509 -req -sha256 -extfile 路径/openssl.cnf -in server.csr -extensions v3_req -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 365
使用certtool工具简单生成证书
上面的一些过程可以使用certtool工具实现相似的功能。
安装软件。
apt-get install gnutls-bin -y
在当前目录新建一个文件夹（要养成不把文件乱扔的习惯）。
mkdir ssl && cd ssl
生成 CA证书
然后用下面的命令代码（8行一起复制一起粘贴一起执行），其中的两个 hello 可以随意改为其他内容，不影响。
echo -e 'cn = "hello" organization = "hello" serial = 1 expiration_days = 365 ca signing_key cert_signing_key crl_signing_key' > ca.tmpl
然后我们生成证书和密匙：
certtool --generate-privkey --outfile ca-key.pem certtool --generate-self-signed --load-privkey ca-key.pem --template ca.tmpl --outfile ca-cert.pem
生成服务器证书
继续用下面的命令代码（6行一起复制一起粘贴一起执行），其中的 1.1.1.1 请改为你的服务器IP，而 hello 可以随意改为其他内容，不影响。
echo -e 'cn = "1.1.1.1" organization = "hello" expiration_days = 365 signing_key encryption_key tls_www_server' > server.tmpl
然后我们生成证书和密匙：
certtool --generate-privkey --outfile server-key.pem certtool --generate-certificate --load-privkey server-key.pem --load-ca-certificate ca-cert.pem --load-ca-privkey ca-key.pem --template server.tmpl --outfile server-cert.pem
大概就是这样。