network debug learning

_posts/2023-09-20-aws-elbv2.md

@@ -0,0 +1,110 @@
+---
+layout: post
+title: "AWS Load Balancer"
+date: 2023-09-20 03:42:00 -0400
+modified_date: 2024-05-28 15:22:00 -0400
+categories: aws elb
+---
+
+# AWS ELB
+
+As the name Elastic Load Balancer says it balances the load by routing traffic across multiple targets.
+Good place to configure and debug how the flow of traffic goes with in AWS.
+
+## Notes
+
+## Useful AWS commands
+
+```sh
+aws elbv2 describe-load-balancers --query 'LoadBalancers[].LoadBalancerName'
+aws elbv2 describe-load-balancers --query 'LoadBalancers[].[LoadBalancerName,LoadBalancerArn]'
+
+
+lb_arn=$(aws elbv2 describe-load-balancers --names "$1" --query 'LoadBalancers[].[LoadBalancerArn]' --output text)
+
+listener_arn=$(aws elbv2 describe-listeners --load-balancer-arn "$lb_arn" --query 'Listeners[].{ListenerArn:ListenerArn,Protocol:Protocol,Port:Port}' | jq -r ".[] | select(.Port=="$2").ListenerArn")
+
+aws elbv2 describe-rules --listener-arn "$listnerarn" --query 'Rules[].{Priority:Priority,Host:Conditions[0].Values[0]}' | jq
+
+```
+
+## Useful scripts
+
+Python script which prints all the hostnames used in the load balancer rounting rule.
+Change the log level to DEBUG to back trace.
+
+```python
+import boto3
+from pprint import pprint
+import json
+import logging
+import sys
+
+
+logger = logging.getLogger('print-aws')
+logger.setLevel(logging.INFO)
+sh = logging.StreamHandler(sys.stdout)
+formatter = logging.Formatter('[%(asctime)s] %(levelname)s [%(filename)s.%(funcName)s:%(lineno)d] %(message)s', datefmt='%a, %d %b %Y %H:%M:%S')
+sh.setFormatter(formatter)
+logger.addHandler(sh)
+
+elbv2 = boto3.client("elbv2")
+
+
+def printEndPointUrls():
+    response= elbv2.describe_load_balancers()
+    loadbalancers = response["LoadBalancers"][2:]
+    logger.debug(response)
+    for lb in loadbalancers:
+        lbArn=lb["LoadBalancerArn"]
+        printLBListeners(lbArn)
+
+
+def printLBListeners(lbArn):
+    logger.debug(lbArn)
+    response = elbv2.describe_listeners(LoadBalancerArn=lbArn)
+    listeners = response["Listeners"]
+    logger.debug(listeners)
+    for listener in listeners:
+        if listener["Protocol"] == "HTTPS" and listener["Port"] == 443:
+            if not listener["DefaultActions"]:
+                logger.debug(listener["DefaultActions"][0]["RedirectConfig"]["Host"])
+            listenerArn = listener["ListenerArn"]
+            printListenerRules(listenerArn)
+
+
+def printListenerRules(listenerArn):
+    logger.debug("printing Listener Rules...")
+    try:
+        response = elbv2.describe_rules(ListenerArn=listenerArn)
+        logger.debug(response)
+        if response["Rules"]:
+            for rule in response["Rules"]:
+                logger.debug(rule)
+                printRule(rule)
+    except Exception as e:
+        logger.error(e)
+        return
+
+
+
+def printRule(rule):
+    try:
+        if rule["Conditions"]:
+            for condition in rule["Conditions"]:
+                if condition["Field"] == "host-header":
+                    print(*condition["Values"], sep = "\n")
+    except Exception as e:
+        logger.error("Error at printing rule \n %s", json.dumps(rule, indent=2))
+        logger.error(e)
+        return
+
+
+if __name__ == "__main__":
+    print(printEndPointUrls())
+        #print(printListenerRules("arn:aws:elasticloadbalancing:......"))
+
+
+```
+
+## Resources

_posts/2023-11-29-networking-commands.md

@@ -2,7 +2,7 @@
 layout: post
 title: "Networking Commands"
 date: 2023-11-29 03:30:00 -0500
-modified_date: 2023-11-29 03:30:00 -0500
+modified_date: 2024-05-28 03:27:00 -0500
 categories: network
 ---
 
@@ -46,7 +46,28 @@ Address:	12.32.0.1#53
 
 Non-authoritative answer:
 *** Can't find cluster0.random.mongodb.net: No answer
+```
+
+To debug add `-debug`
 
+```
+$ nslookup -debug google.com
+Server:         100.64.0.1
+Address:        100.64.0.1#53
+
+------------
+    QUESTIONS:
+        google.com, type = A, class = IN
+    ANSWERS:
+    ->  google.com
+        internet address = 142.250.217.238
+        ttl = 54
+    AUTHORITY RECORDS:
+    ADDITIONAL RECORDS:
+------------
+Non-authoritative answer:
+Name:   google.com
+Address: 142.250.217.238
 ```
 
 ### dig
@@ -142,8 +163,14 @@ $ traceroute google.com
 
 ### Debugging tools
 
-In linux (Ubuntu), to get some basic commands, install net-tools.
+In linux (Ubuntu), to get some basic commands (ex: dig, nslookup), install them using following commands.
 
 ```
 $ sudo apt install net-tools
 ```
+
+or in AWS cloudshell...
+
+```
+$ sudo yum install -y bind-utils
+```