communicator/ssh: set TCP keep-alive [GH-872]

CHANGELOG.md

@@ -20,6 +20,7 @@ BUG FIXES:
   checksum type is "none"
 * builder/virtualbox,vmware/qemu: Support for additional scancodes for
   `boot_command` such as `<up>`, `<left>`, `<insert>`, etc. [GH-808]
+* communicator/ssh: Send TCP keep-alives on connections. [GH-872]
 * provisioners/ansible-local: Properly upload custom playbooks. [GH-829]
 
 ## 0.5.1 (01/02/2014)

communicator/ssh/connect.go

@@ -10,6 +10,13 @@ import (
 // is suitable for use with the SSH communicator configuration.
 func ConnectFunc(network, addr string) func() (net.Conn, error) {
 	return func() (net.Conn, error) {
-		return net.DialTimeout(network, addr, 15*time.Second)
+		c, err := net.DialTimeout(network, addr, 15*time.Second)
+		if err != nil {
+			return nil, err
+		}
+
+		if tcpConn, ok := c.(*net.TCPConn); ok {
+			tcpConn.SetKeepAlive(true)
+		}
 	}
 }