Replaced net.ErrClosed with a string test since net.ErrClosed was only exposed in 1.6
--- a/sshd/server.go
+++ b/sshd/server.go
@@ -2,9 +2,9 @@
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"net"
+	"strings"
 	"sync"
 
 	"github.com/armon/go-radix"
@@ -172,7 +172,8 @@
 	for {
 		c, err := s.listener.Accept()
 		if err != nil {
-			if !errors.Is(err, net.ErrClosed) {
+			str := err.Error()
+			if !strings.Contains(str, "use of closed network connection"){
 				s.l.WithError(err).Warn("Error in listener, shutting down")
 			}
 			return