IO::Socket::SSL - establishing client connection - perl

Question

As per the documentation of IO::Socket::SSL (PERL) I understand that if I want to just send command to specific server-program that running on port 9999 on my host, Ican do it this way:
my $cl=IO::Socket::SSL->new("localhost:9999"); # locallost is my real case, anyway
if($cl) {
$cl->connect_SSL or die $#;
# Something about certificates?
$cl->syswrite("Command");
close($cl);
}
But the error I get is: "SSL connect attempt failed with unknown error error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol at blabla.cgi line 888"
The server initialized thi way (in another pl program):
use IO::Socket::SSL;
use Net::WebSocket::Server;
my $CON={};
my #crt=&SSLCerts(); die 'E101' if(#crt==0);
my $ssl=IO::Socket::SSL->new(
Listen => 10000,
Timeout => 45,
LocalPort => 9999,
Proto => 'tcp',
SSL_cert_file => "$EF::Base/ssl/certs/$crt[0][0].crt",
SSL_key_file => "$EF::Base/ssl/keys/$crt[1][0].key"
) or die "E102: $!";
Net::WebSocket::Server->new(
listen => $ssl,
silence_max=> 3600,
tick_period => 5,
on_tick => sub {
# Empty for now
},
on_connect => sub {
my($serv,$conn)=#_; my($cid,$sid);
$conn->on(
handshake => sub {
my($cnc,$hdk)=#_;
my $nsn=$hdk->req->resource_name;
$cid=substr($nsn,4,index($nsn,'&L=')-4);
$CON->{$cid}=$cnc; # Register incomming connection
},
binary => sub {
# Handle incomming message from the client
},
disconnect => sub {
delete $CON->{$cid};
}
);
}
)->start;
Typical Websocket client that is connecting from the browser via "wss://" connects without any trouble.... The server MUST be SSL...
Here I am just trying to do the same from within perl.
What I am doing wrong? Nothing mentioned about certificates in client, only in server - the server is working fine. Maybe configuration? I have purchased SSL certificates and I use them for the server that running ok on that port.
The host is Linux (CentOS - if it matters).

Answer 1

... SSL23_GET_SERVER_HELLO:unknown protocol
This is the kind of error you get if the client tries to do a SSL handshake and the server responds with something which is not SSL. Typically this happens if you connect to a server which is not (properly) SSL enabled (at least not on this port) or requires some plain text to upgrade to SSL (like in case of SMTP STARTTLS and similar).
This kind of error has usually nothing to do with certificates.
This kind of error can only happen if you try to do an SSL handshake on an already established SSL socket but the server does not expect this. This seems to happen in your case:
my $cl=IO::Socket::SSL->new("localhost:9999"); # locallost is my real case, anyway
if($cl) {
$cl->connect_SSL or die $#;
...
The SSL connection is already being established by IO::Socket::SSL->new. This is the same with IO::Socket::INET or similar: if the target is given it will already connect inside new and an additional connect or connect_SSL should not be done. This is also reflected in the documentation and examples.
Since version 2.045 (released 02/2017) IO::Socket::SSL will simply ignore a connect_SSL if the SSL handshake is already done. You are likely using an older version of IO::Socket::SSL where connect_SSL will start a new handshake even if the TLS handshake was already finished. This handshake inside the TLS connection will result in the strange error you see.