Objective-C

POP3 over Multiple Hop SSH

Demonstrates how to read POP3 email (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => POP3Server

Objective-C

#import <CkoSsh.h>
#import <CkoMailMan.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.

CkoSsh *ssh1 = [[CkoSsh alloc] init];

// Connect directly to the 1st SSH server.
success = [ssh1 Connect: @"serverssh1.com" port: [NSNumber numberWithInt: 22]];
if (success == NO) {
    NSLog(@"%@",ssh1.LastErrorText);
    return;
}

// Authenticate using login/password:
success = [ssh1 AuthenticatePw: @"ssh1Login" password: @"ssh1Password"];
if (success == NO) {
    NSLog(@"%@",ssh1.LastErrorText);
    return;
}

// Connect through the 1st SSH connection to reach a 2nd SSH server.
// Note: Any number of SSH connections may be simultaneously tunneled through a single
// existing SSH connection.
CkoSsh *ssh2 = [[CkoSsh alloc] init];
success = [ssh2 ConnectThroughSsh: ssh1 hostname: @"serverssh2.com" port: [NSNumber numberWithInt: 22]];
if (success == NO) {
    NSLog(@"%@",ssh2.LastErrorText);
    return;
}

// Authenticate with ssh2...
success = [ssh2 AuthenticatePw: @"ssh2Login" password: @"ssh2Password"];
if (success == NO) {
    NSLog(@"%@",ssh2.LastErrorText);
    return;
}

CkoMailMan *mailman = [[CkoMailMan alloc] init];

// Tell the mailman object to connect to the POP3 server though the ssh2 tunnel (which itself is routed through ssh1).
// The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => POP3Server
success = [mailman UseSsh: ssh2];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

// Set the POP3 server's hostname
mailman.MailHost = @"pop.example.com";

// Set the POP3 login/password.
mailman.PopUsername = @"myLogin";
mailman.PopPassword = @"myPassword";

// Establish the POP3 connection through the ssh2 tunnel.
success = [mailman Pop3BeginSession];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

// Get the number of messages in the mailbox.
int numMessages = [[mailman GetMailboxCount] intValue];

CkoEmail *email = [[CkoEmail alloc] init];
int i = 1;
while (i <= numMessages) {
    // Fetch by the message number (not by the UIDL)
    success = [mailman FetchOne: NO numBodyLines: [NSNumber numberWithInt: 0] msgNum: [NSNumber numberWithInt: i] email: email];
    if (success == NO) {
        NSLog(@"%@",mailman.LastErrorText);
        return;
    }

    NSLog(@"%@%@%@%@",email.From,@": ",email.Subject,@"\n");

    i = i + 1;
}

// Close the connection with the POP3 server.  (This closes the tunnel through ssh2)
// The connection with ssh2 is still alive, and may be used for more connections.
success = [mailman Pop3EndSession];

// Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
// The connection with ssh1 is still alive, and may be used for more connections.

[ssh2 Disconnect];

[ssh1 Disconnect];