Tcl

SSH Public Key Authentication

Demonstrates authenticating with an SSH server using public-key authentication. A private key is loaded into an SshKey object and passed to AuthenticatePk. The matching public key must already be installed on the server for the account.

Note: The private-key path is relative to the application's current working directory. Supply the path to your own key file.

Background: Public-key authentication is the standard for unattended and automated SSH: the private key never leaves the client, the server merely trusts the corresponding public key, and no reusable password crosses the wire. SshKey imports several formats — OpenSSH PEM keys via FromOpenSshPrivateKey and PuTTY .ppk files via FromPuttyPrivateKey — encrypted or not. For an encrypted key, set the Password property before importing. Note that LoadText is only a convenience for reading a text file into a string; it does not itself load the key.

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Tcl


load ./chilkat.dll

set success 0

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

#  Demonstrates authenticating with an SSH server using public-key authentication.  The matching
#  public key must already be installed on the SSH server for the account.

set ssh [new_CkSsh]

#  Timeouts, in milliseconds.
CkSsh_put_ConnectTimeoutMs $ssh 5000
CkSsh_put_ReadTimeoutMs $ssh 15000

set hostname "ssh.example.com"
set port 22
set success [CkSsh_Connect $ssh $hostname $port]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  LoadText is a convenience method that reads any text file into a string.  It does not itself
#  load the key.
set key [new_CkSshKey]

set privKeyText [CkSshKey_loadText $key "qa_data/my_private_key.pem"]
if {[CkSshKey_get_LastMethodSuccess $key] == 0} then {
    puts [CkSshKey_lastErrorText $key]
    delete_CkSsh $ssh
    delete_CkSshKey $key
    exit
}

#  Import the private key.  Both OpenSSH and PuTTY formats are supported, encrypted or not.
#  This example loads an unencrypted OpenSSH-format key; for a PuTTY .ppk file, call
#  FromPuttyPrivateKey instead.  For an encrypted key, set key.Password before importing.
set success [CkSshKey_FromOpenSshPrivateKey $key $privKeyText]
if {$success == 0} then {
    puts [CkSshKey_lastErrorText $key]
    delete_CkSsh $ssh
    delete_CkSshKey $key
    exit
}

set success [CkSsh_AuthenticatePk $ssh "mySshLogin" $key]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    delete_CkSshKey $key
    exit
}

puts "Public-key authentication successful."

CkSsh_Disconnect $ssh

delete_CkSsh $ssh
delete_CkSshKey $key