Objective-C

POP3 SSH Tunneling (Port Forwarding)

Demonstrates how to connect to a POP3 server through an SSH tunnel. Reads a POP3 mailbox and display the FROM and SUBJECT header fields of each email. Objective-C

#import <CkoMailMan.h>
#import <NSString.h>
#import <CkoEmail.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The mailman object is used for receiving (POP3) 
//  and sending (SMTP) email.
CkoMailMan *mailman = [[CkoMailMan alloc] init];

//  The SSH hostname may be a hostname or an 
//  IP address, such as "192.168.1.108".
//  The port is typically 22 (the standard port for SSH).
NSString *sshHostname = @"sftp.example.com";
int sshPort = 22;

//  Connect to an SSH server and establish the SSH tunnel:
success = [mailman SshOpenTunnel: sshHostname sshPort: [NSNumber numberWithInt: sshPort]];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  Authenticate with the SSH server via a login/password
//  or with a public key.
//  This example demonstrates SSH password authentication.
//  Note: This is not authenticating with the POP3 server, it is
//  for authenticating with the SSH server, which is separate.
success = [mailman SshAuthenticatePw: @"ssh_login" sshPassword: @"ssh_password"];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  OK, the SSH tunnel is setup.  The mailman may
//  be used exactly the same as usual, except all communications
//  are now sent through the SSH tunnel.

//  The SSH tunnel may be kept open for any number of 
//  POP3 connections.  

//  Set the POP3 server's hostname
mailman.MailHost = @"mail.my-pop3-server.com";

//  Set the POP3 settings for your POP3 server:
mailman.PopUsername = @"pop3_login";
mailman.PopPassword = @"pop3_password";
mailman.MailPort = [NSNumber numberWithInt:995];
mailman.PopSsl = YES;

//  Connect to the POP3 server through the already-established SSH tunnel:
success = [mailman Pop3BeginSession];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  A visual inspection of the LastErrorText after
//  a successful POP3 connection will confirm the SSH tunneling.
//  Note: If the POP3 connection uses SSL/TLS, then the SSL/TLS 
//  secure channel will be wrapped within the SSH tunnel.
NSLog(@"%@",mailman.LastErrorText);

//  How many messages are in the POP3 inbox?
int numToDownload = [[mailman GetMailboxCount] intValue];
if (numToDownload > 5) {
    numToDownload = 5;
}

if (numToDownload == 0) {
    NSLog(@"%@",@"No messages in the POP3 inbox.");
    return;
}

//  Download a max of 5 messages
int i;
CkoEmail *email = [[CkoEmail alloc] init];
for (i = 1; i <= numToDownload; i++) {
    success = [mailman FetchOne: NO numBodyLines: [NSNumber numberWithInt: 0] msgNum: [NSNumber numberWithInt: i] email: email];
    if (success == NO) {
        NSLog(@"%@",mailman.LastErrorText);
        return;
    }

    NSLog(@"%@",email.From);
    NSLog(@"%@",email.Subject);
    NSLog(@"%@",@"----");
}

//  Close the connection with the POP3 server, leaving the SSH tunnel open for subsequent POP3 connections.
success = [mailman Pop3EndSession];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  Try connecting to a different POP3 server through the same aleady setup SSH tunnel:
//  Set the POP3 server's hostname
mailman.MailHost = @"mail.my-pop3-server2.com";

//  Set the POP3 settings for your POP3 server:
mailman.PopUsername = @"pop3_login2";
mailman.PopPassword = @"pop3_password2";
mailman.MailPort = [NSNumber numberWithInt:110];
mailman.PopSsl = NO;

success = [mailman Pop3BeginSession];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  Review the LastErrorText to see that the connection was made via the SSH tunnel:
NSLog(@"%@",mailman.LastErrorText);

success = [mailman Pop3EndSession];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

//  Close the SSH tunnel.
success = [mailman SshCloseTunnel];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}