VB.NET
SSH Tunnel Set Allowed Algorithms

Demonstrates how to explicitly set the algorithms allowed in the SSH connection protocol for SSH tunneling.
Note: This example requires Chilkat v9.5.0.99 or greater.
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VB.NET
Dim success As Boolean = False

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

Dim ssh_tunnel As New Chilkat.SshTunnel

Dim json As New Chilkat.JsonObject

' Here are the algorithms supported by Chilkat at the time this example was written (14-June-2024)

' ---------------------------
' SSH Key-Exchange Algorithms
' ---------------------------
' curve25519-sha256
' curve25519-sha256@libssh.org
' ecdh-sha2-nistp256
' ecdh-sha2-nistp384
' ecdh-sha2-nistp521
' diffie-hellman-group14-sha256
' diffie-hellman-group16-sha512
' diffie-hellman-group18-sha512
' diffie-hellman-group-exchange-sha256
' diffie-hellman-group1-sha1
' diffie-hellman-group14-sha1
' diffie-hellman-group-exchange-sha1

' ---------------------------
' SSH Host Key Algorithms
' ---------------------------
' ssh-ed25519
' ecdsa-sha2-nistp256
' ecdsa-sha2-nistp384
' ecdsa-sha2-nistp521
' rsa-sha2-256
' rsa-sha2-512
' ssh-rsa
' ssh-dss

' ---------------------------
' SSH Cipher Algorithms
' ---------------------------
' chacha20-poly1305@openssh.com
' aes128-ctr
' aes256-ctr
' aes192-ctr
' aes128-cbc
' aes256-cbc
' aes192-cbc
' aes128-gcm@openssh.com
' aes256-gcm@openssh.com
' twofish256-cbc
' twofish128-cbc
' blowfish-cbc

' ---------------------------
' SSH MAC Algorithms
' ---------------------------
' hmac-sha2-256
' hmac-sha2-512
' hmac-sha2-256-etm@openssh.com
' hmac-sha2-512-etm@openssh.com
' hmac-sha1-etm@openssh.com
' hmac-sha1
' hmac-ripemd160
' hmac-sha1-96
' hmac-md5

' Specify the allowed key-exchange, host-key, cipher (i.e. encryption), and mac (i.e. hash) algorithms allowed, in the order of preference.
' -------------------------------------------------------------------------------------------------------------------------------------------
' Note: You typically should NOT explicitly set allowed algorithms.
' By default, Chilkat orders algorithms according to best practices, and pays attention to vulnerabilities such as the "Terrapin Attack".
' Hard-coding algorthims can make your application brittle and prone to breaking over a long period of time,
' if a server (at some point in the future) changes its allowed algorithms, or if you connect to a different server,
' such that the client (Chilkat) and server cannot find a set of mutually agreed-upon algorithms.
' -------------------------------------------------------------------------------------------------------------------------------------------
Dim allowed_kex As String = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256"
Dim allowed_hostKey As String = "ssh-ed25519,ecdsa-sha2-nistp256"
Dim allowed_cipher As String = "chacha20-poly1305@openssh.com,aes256-ctr"
Dim allowed_mac As String = "hmac-sha2-256,hmac-sha2-512"

json.UpdateString("kex",allowed_kex)
json.UpdateString("hostKey",allowed_hostKey)
json.UpdateString("cipher",allowed_cipher)
json.UpdateString("mac",allowed_mac)
ssh_tunnel.SetAllowedAlgorithms(json)

Dim port As Integer = 22
success = ssh_tunnel.Connect("example.com",port)
If (success <> True) Then
    Debug.WriteLine(ssh_tunnel.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Connected.")

' ....
' ....