CkPython

Initiate an SSH Key Re-Exchange

Demonstrates the Chilkat Ssh.ReKey method, which initiates an SSH key re-exchange and waits for it to complete. It takes no arguments. Either the client or the server may trigger rekeying at any time.

Background: Rekeying periodically replaces the session keys to limit how much data is protected by any single key. RFC 4253 recommends it after roughly one gigabyte of transfer or one hour, whichever comes first. In practice servers initiate this automatically and Chilkat handles it transparently, so calling ReKey explicitly is rarely necessary.

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import sys
import chilkat

success = False

#  Demonstrates the Ssh.ReKey method, which initiates an SSH key re-exchange and waits for it to
#  complete.  It takes no arguments.  In normal use the server initiates rekeying as needed and
#  Chilkat handles it transparently.

ssh = chilkat.CkSsh()

#  Connect to the SSH server.  Port 22 is the usual SSH port.
sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

#  Explicitly initiate a key re-exchange on the live connection.
success = ssh.ReKey()
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

print("Key re-exchange complete.")

ssh.Disconnect()