fix: snmpv3 in ipv6

sshsvc/telnet/telnet.go

@@ -18,7 +18,7 @@ type TelnetHandler struct {
 	UserName   string
 	Password   string
 	AuthType   string
-	MaxConnNum uint8
+	MaxConnNum int
 	TagNE      string
 	ListenHost string
 
@@ -65,7 +65,8 @@ func (t *TelnetHandler) StartTelnetServer() {
 		t.mu.Lock()
 		if t.connCount >= int(t.MaxConnNum) {
 			t.mu.Unlock()
-			io.WriteString(conn, "Connection limit reached. Try again later.\r\n")
+			msg := fmt.Sprintf("Connection limit reached (limit=%d). Try again later.\r\n", t.MaxConnNum)
+			io.WriteString(conn, msg)
 			conn.Close()
 			continue
 		}
@@ -88,7 +89,8 @@ func (t *TelnetHandler) handleTelnetConnection(conn net.Conn) {
 	writer := bufio.NewWriter(conn)
 
 	// 发送欢迎信息
-	writer.WriteString("Welcome to the Telnet server!\r\n")
+
+	writer.WriteString(fmt.Sprintf("\r\nWelcome to the %s server!\r\n", strings.ToUpper(t.TagNE)))
 	writer.Flush()
 
 	// 请求用户名
@@ -129,7 +131,8 @@ func (t *TelnetHandler) handleTelnetConnection(conn net.Conn) {
 	writer.Flush()
 
 	if t.handleTelnetAuth(t.AuthType, user, pass) {
-		writer.WriteString("\r\nAuthentication successful!\r\n")
+		msg := fmt.Sprintf("\r\n\r\nLast login: %s from %s \r\n\r\n", time.Now().Format(time.RFC1123), conn.RemoteAddr())
+		writer.WriteString(msg)
 		writer.Flush()
 		t.HandleCommands(user, t.TagNE, reader, writer)
 	} else {
@@ -181,7 +184,7 @@ func (t *TelnetHandler) HandleCommands(user, tag string, reader *bufio.Reader, w
 		case "time":
 			writer.WriteString(fmt.Sprintf("\r\nCurrent time: %s\r\n", time.Now().Format(time.RFC1123)))
 		case "exit", "quit":
-			writer.WriteString("\r\nGoodbye!\r\n")
+			writer.WriteString("\r\n\r\nGoodbye!\r\n")
 			writer.Flush()
 			return
 		case "":