要解决AWS ALB（应用负载均衡器）与Palo Alto VM防火墙之间未传递“X-Forwarded-Proto”的问题，你可以通过以下步骤进行操作：

1. 在Palo Alto VM防火墙上创建一个自定义URL过滤器，以便在HTTP请求头中添加“X-Forwarded-Proto”字段。

conf
set device-group  url-filtering custom-url-category  override yes
set device-group  url-filtering custom-url-category  header X-Forwarded-Proto https

2. 在安全策略规则中启用URL过滤器，以确保流量通过自定义URL过滤器。

conf
set device-group  pre-rulebase security rules  url-filtering yes

3. 在AWS ALB中配置HTTP请求头设置，以将“X-Forwarded-Proto”传递给Palo Alto VM防火墙。

{
  "Type": "AWS::ElasticLoadBalancingV2::ListenerRule",
  "Properties": {
    "Actions": [
      {
        "Type": "forward",
        "TargetGroupArn": ""
      }
    ],
    "Conditions": [
      {
        "Field": "host-header",
        "HostHeaderConfig": {
          "Values": [""]
        }
      }
    ],
    "ListenerArn": "",
    "Priority": 1
  }
}

4. 在AWS ALB目标组中启用代理协议以传递“X-Forwarded-Proto”。

{
  "Type": "AWS::ElasticLoadBalancingV2::TargetGroup",
  "Properties": {
    "Name": "",
    "Port": 80,
    "Protocol": "HTTP",
    "TargetType": "instance",
    "HealthCheckIntervalSeconds": 30,
    "HealthCheckPath": "/",
    "HealthCheckProtocol": "HTTP",
    "HealthCheckTimeoutSeconds": 5,
    "HealthyThresholdCount": 2,
    "UnhealthyThresholdCount": 2,
    "Matcher": {
      "HttpCode": "200"
    },
    "TargetGroupAttributes": [
      {
        "Key": "proxy_protocol_v2.enabled",
        "Value": "true"
      }
    ],
    "VpcId": ""
  }
}

请根据你的具体环境和需求修改上述代码示例中的参数。这些步骤将确保AWS ALB夹层与Palo Alto VM防火墙之间传递“X-Forwarded-Proto”字段。