> ## Documentation Index > Fetch the complete documentation index at: https://site.aspect.build/llms.txt > Use this file to discover all available pages before exploring further. # Tcp `function` **Tcp.connect** 
        
          def Tcp.connect(
          addr: str,
          /,
          \*,
          timeout\_ms: None | int = None
          ) -> std.net.TcpStream
Connect to `addr`, `"host:port"` (an IPv6 host in brackets: `"[::1]:6379"`). Each address the host resolves to is tried in turn, all within `timeout_ms`, which bounds the name lookup too; `None` waits as long as the OS does. A failure raises `std.io.Error`, e.g. `kind == "connection_refused"` or `"timed_out"`. `function` **Tcp.listen** 
        
          def Tcp.listen(
          addr: str,
          /
          ) -> std.net.TcpListener
Listen on `addr`, `"host:port"`. Port `0` picks a free port; the listener's `local_addr()` says which. `function` **Tcp.try\_connect** 
        
          def Tcp.try\_connect(
          addr: str,
          /,
          \*,
          timeout\_ms: None | int = None
          ) -> (None | std.io.Error, None | std.net.TcpStream)
`connect`, returning an `(err, stream)` pair instead of raising a `std.io.Error`. `function` **Tcp.try\_listen** 
        
          def Tcp.try\_listen(
          addr: str,
          /
          ) -> (None | std.io.Error, None | std.net.TcpListener)
`listen`, returning an `(err, listener)` pair instead of raising a `std.io.Error`.