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IO::Socket::SSL::InterUser(Contributed Perl DocumIO::Socket::SSL::Intercept(3)
NAME
       IO::Socket::SSL::Intercept -- SSL interception (man in the middle)
SYNOPSIS
           use IO::Socket::SSL::Intercept;
           # create interceptor with proxy certificates
           my $mitm = IO::Socket::SSL::Intercept->new(
               proxy_cert_file => 'proxy_cert.pem',
               proxy_key_file  => 'proxy_key.pem',
               ...
           );
           my $listen = IO::Socket::INET->new( LocalAddr => .., Listen => .. );
           while (1) {
               # TCP accept new client
               my $client = $listen->accept or next;
               # SSL connect to server
               my $server = IO::Socket::SSL->new(
                   PeerAddr => ..,
                   SSL_verify_mode => ...,
                   ...
               ) or die "ssl connect failed: $!,$SSL_ERROR";
               # clone server certificate
               my ($cert,$key) = $mitm->clone_cert( $server->peer_certificate );
               # and upgrade client side to SSL with cloned certificate
               IO::Socket::SSL->start_SSL($client,
                   SSL_server => 1,
                   SSL_cert => $cert,
                   SSL_key => $key
               ) or die "upgrade failed: $SSL_ERROR";
               # now transfer data between $client and $server and analyze
               # the unencrypted data
               ...
           }
DESCRIPTION
       This module provides functionality to clone certificates and sign them
       with a proxy certificate, thus making it easy to intercept SSL
       connections (man in the middle). It also manages a cache of the
       generated certificates.
How Intercepting SSL Works
       Intercepting SSL connections is useful for analyzing encrypted traffic
       for security reasons or for testing. It does not break the end-to-end
       security of SSL, e.g. a properly written client will notice the
       interception unless you explicitly configure the client to trust your
       interceptor.  Intercepting SSL works the following way:
       o   Create a new CA certificate, which will be used to sign the cloned
           certificates.  This proxy CA certificate should be trusted by the
           client, or (a properly written client) will throw error messages or
           deny the connections because it detected a man in the middle
           attack.  Due to the way the interception works there no support for
           client side certificates is possible.
           Using openssl such a proxy CA certificate and private key can be
           created with:
             openssl genrsa -out proxy_key.pem 1024
             openssl req -new -x509 -extensions v3_ca -key proxy_key.pem -out proxy_cert.pem
             # export as PKCS12 for import into browser
             openssl pkcs12 -export -in proxy_cert.pem -inkey proxy_key.pem -out proxy_cert.p12
       o   Configure client to connect to use intercepting proxy or somehow
           redirect connections from client to the proxy (e.g. packet filter
           redirects, ARP or DNS spoofing etc).
       o   Accept the TCP connection from the client, e.g. don't do any SSL
           handshakes with the client yet.
       o   Establish the SSL connection to the server and verify the servers
           certificate as usually. Then create a new certificate based on the
           original servers certificate, but signed by your proxy CA.  This is
           the step where IO::Socket::SSL::Intercept helps.
       o   Upgrade the TCP connection to the client to SSL using the cloned
           certificate from the server. If the client trusts your proxy CA it
           will accept the upgrade to SSL.
       o   Transfer data between client and server. While the connections to
           client and server are both encrypted with SSL you will read/write
           the unencrypted data in your proxy application.
METHODS
       IO::Socket::SSL::Intercept helps creating the cloned certificate with
       the following methods:
       $mitm = IO::Socket::SSL::Intercept->new(%args)
           This creates a new interceptor object. %args should be
           proxy_cert X509 | proxy_cert_file filename
                   This is the proxy certificate.  It can be either given by
                   an X509 object from Net::SSLeays internal representation,
                   or using a file in PEM format.
           proxy_key EVP_PKEY | proxy_key_file filename
                   This is the key for the proxy certificate.  It can be
                   either given by an EVP_PKEY object from Net::SSLeays
                   internal representation, or using a file in PEM format.
                   The key should not have a passphrase.
           pubkey EVP_PKEY | pubkey_file filename
                   This optional argument specifies the public key used for
                   the cloned certificate.  It can be either given by an
                   EVP_PKEY object from Net::SSLeays internal representation,
                   or using a file in PEM format.  If not given it will create
                   a new public key on each call of "new".
           serial INTEGER|CODE
                   This optional argument gives the starting point for the
                   serial numbers of the newly created certificates. If not
                   set the serial number will be created based on the digest
                   of the original certificate. If the value is code it will
                   be called with
                   "serial(original_cert,CERT_asHash(original_cert))" and
                   should return the new serial number.
           cache HASH | SUBROUTINE
                   This optional argument gives a way to cache created
                   certificates, so that they don't get recreated on future
                   accesses to the same host.  If the argument ist not given
                   an internal HASH ist used.
                   If the argument is a hash it will store for each generated
                   certificate a hash reference with "cert" and "atime" in the
                   hash, where "atime" is the time of last access (to expire
                   unused entries) and "cert" is the certificate. Please note,
                   that the certificate is in Net::SSLeays internal X509
                   format and can thus not be simply dumped and restored.  The
                   key for the hash is an "ident" either given to "clone_cert"
                   or generated from the original certificate.
                   If the argument is a subroutine it will be called as
                   "$cache->(ident,sub)".  This call should return either an
                   existing (cached) "(cert,key)" or call "sub" without
                   arguments to create a new "(cert,key)", store it and return
                   it.  If called with "$cache->('type')" the function should
                   just return 1 to signal that it supports the current type
                   of cache. If it reutrns nothing instead the older cache
                   interface is assumed for compatibility reasons.
       ($clone_cert,$key) = $mitm->clone_cert($original_cert,[ $ident ])
           This clones the given certificate.  An ident as the key into the
           cache can be given (like "host:port"), if not it will be created
           from the properties of the original certificate.  It returns the
           cloned certificate and its key (which is the same for alle created
           certificates).
       $string = $mitm->serialize
           This creates a serialized version of the object (e.g. a string)
           which can then be used to persistantly store created certificates
           over restarts of the application. The cache will only be serialized
           if it is a HASH.  To work together with Storable the
           "STORABLE_freeze" function is defined to call "serialize".
       $mitm = IO::Socket::SSL::Intercept->unserialize($string)
           This restores an Intercept object from a serialized string.  To
           work together with Storable the "STORABLE_thaw" function is defined
           to call "unserialize".
AUTHOR
       Steffen Ullrich
perl v5.26.3                      2019-02-21     IO::Socket::SSL::Intercept(3)