Pandas

This is something I have heard about in the past but never used. So this week, as finally decided to write a script to help me to find the peers of flapping ports, learned about pandas from first time. I used another script as “inspiration” and after seeing it was using pandas, I decided to read a bit about it and give it a go.

The main type is the DataFrame. In my head, pandas is just a library to deal with CSV, spreadsheets, etc like when you use a program like libreoffice. And this page, gave me the hints for creating the query I wanted to make.

So at the end I have my very basic script but saves me time logging to each device and find the peer port.

Of course, there are different ways to tackle this problem, but in my environment, the source of truth for links is in a file. You could have that info in the port description too, or in a database, etc.

$ python3 flapping-peer.py -f flapping-list.txt

Result:
SW1 Ethernet1/1 SW2 Ethernet1/1
SW1 Ethernet1/4 SW2 Ethernet1/4

$  
$ cat flapping-list.txt 
SW1,Ethernet1/1
SW2,Ethernet1/4
$
$ cat patching-file.csv 
Site,Source Device,Source Interface,Destination Device,Destination Interface,Media
A,SW1,Ethernet1/1,SW2,Ethernet1/1,SMF
A,SW1,Ethernet1/2,SW2,Ethernet1/2,SMF
A,SW1,Ethernet1/3,SW2,Ethernet1/3,SMF
A,SW1,Ethernet1/4,SW2,Ethernet1/4,SMF
A,SW1,Ethernet1/5,SW2,Ethernet1/5,SMF
$

TCP Asymmetric

I got escalated an issue recently that had caused several outages and needed an urgent fix.

For different reasons, we had asymmetric routing in SITE-A. The normal flow is the green arrow. During the asymmetric routing, the flow is the red line. Routing wise, things should work. BUT, we have firewalls in the path. The firewalls were configured to allow asymmetric connections (I was told). As far as I could see in the config and logs, nothing was dropped in the firewalls during the issue.

So first thing, I fixed the asymmetric routing so it didnt happen again. I took me a while to come up with the solution (and it was quite simple) as I had to understand properly the routing before and during the issue. The diagram is quite simplified at the end of the day.

So during the maintenance window when I applied the fix for the asymmetric routing, I managed to take some traces in the firewalls, as I was trying to understand where the traffic was dropped/lost during the asymmetric scenario. As well, I was not very familiar with several parts of the network and the monitoring, I didnt know which links where already tapped or not. Once I was happy with the routing fix, I tried to take a look at the traces. At high level, I could see the return traffic leaving FW1 and leaving DC1-SW1. Based on that, I started to think that the firewalls were fine…..

In another maintenance, I tried to take more logs in different part of the network and I could see clearly the traffic reaching A-SW1. As I ran of time and missed to tap some links, I couldnt carry on.

So based on the second maintenance, the issue had to be inside SITE-A. Somehow it didnt make sense. I checked I didnt have uRPF enabled. The rest was pure L2 so it couldnt see the L3…

So in the third maintenance, I got all my debugging tools to verify that any network kit was dropping the traffic in SITE-A…. and it was useless. I realized that I could do a tcpdump in the client IP1 i was using for testing and I could see some return traffic!!!!

So, I was just socked. I didnt get it. It didnt make sense.

Somehow, I reviewed the tcp captures I was doing in each interface of both firewalls. I was trying to get to basics.

I was assuming the TCP handshake was completed properly. After paying a bit of attention to the client logs… I could see the TCP handshake completed. And I could see the HTTP GET getting to and leaving DC2-FW…. so why the server IP2 was not answering!!!!???

So back to the tcp handshake and firewall captures, I was comparing step by step. Somehow, I missed that the TCP ACK from client IP2 was reaching DC2-FW…. but it was not leaving DC2-FW!!!! even worse, the HTTP GET it was actually crossing the DC2-FW !!!

SLAP IN THE FACE!!!

This is the TCP handshake. This is networking 101…..

The TCP state-machine in client and server during the asymmetric scenario

So I was asumming that because the client was sending HTTP get, the tcp handshake was completed in both ends!!!!

It didnt make sense why I was seeing TCP SYN-ACK retransmissions from the server IP1…. BECAUSE the TCP ACK from client IP2 never reached.

For that reason server IP2 never answered the HTTP GET, because from its end the tcp hanshake was not completed.

I banged my head several times on the table. I “saw” this during the first maintenance window when I took the tcpdump in the firewalls BUT I didnt pay attention to the basic details.

I trusted too much to see a wireshark trace because it is more visual and shows more info but the clues were all the time in the tcpdump from the firewalls that I didnt bother to pay full attention.

At least, I found out where and why the connections failed during the asymmetric routing scenario. A firewall upgrade did the job.

So all fixed.

Lessons learned:

  • without proper foundation, you can’t build knowledge (tcp handshake state in client and server)
  • when things dont make sense, get back to basics (tcp handshake)
  • get the most of the tools at hand (tcpdump – PSH packets were the HTTP GET !!!!)

Sourdough Focaccia (II)

I tried some time ago sourdough focaccia but I wasnt really happy with the result and somehow found this video and decided to try again.

Ingredients:

  • 320g water
  • 100g sourdough starter
  • 400g strong white flour
  • 15g olive oil
  • 8g salt
  • 15g oil + 15g water
  • toppings: sliced onion, cherry tomatoes and slice green/black olives
  • salt, pepper, herbs

Process

  • Add the active starter to the water, mix well
  • Add flour and oil, mix a bit.
  • Add salt and mix well.
  • Cover it and let it rest for 30 minutes.
  • Make 1 fold
  • Cover and let it rest again for 30 minutes
  • Make 1 fold
  • Cover and let it rest for 2-3h.
  • Make a “coil” fold
  • Cover and let it rest in the fridge overnight (12-14h)
  • Take the dough out of the fridge. On a lightly dusted table top, shape the dough, trying to keep as much air inside (most difficult part for me)
  • Oil a pan and put the dough on it. Let is rise for 3h
  • Pre-heat oven at 230C
  • Mix oil + water. Pour on the dough and with clean hands, make pockets with your fingers.
  • Fill the pockets with your toppings (onion, tomatoes and olives)
  • Add some salt, pepper and herbs of your choice (oregano, basil, rosemary, etc)
  • Bake for 25 minutes or till the top is crispy at 230C.
  • Remove from oven and let it cool down

This is the result!

whole foccacia

sliced foccacia

It was very tasty, spongy and moist. Not as much open crumb like the video but really happy with the result!

Foundation’s Edge

This is the forth book of the series. I was a bit weary at the beginning as I thought it was going to be a boring continuation (like it was my last Dune book). But it hooked me and read it voraciously. I was surprised how quickly I finished it. I liked how all the parts are faced at the end and the goals they want to achieve plus how different are the personalities of each character.

It was interesting after four books, that is the first time it is mentioned alien life and robots. Thinking this is sci-fi based on a very far future I should have noticed that very early on the series but still it is really engaging with all the twists.

Looking forwards for the next books!

Attached

This book was a gift from a very good friend. It has been an interesting read as it has helped me to put labels to my own behaviours and explain some situations in my last (and only) relationship.

The book states there are mainly three type of behaviours in relationships

  • Secure: comfortable with intimacy and communicating.
  • Avoidant: dont want to get to close for fear to lose independency
  • Anxious: too preoccupied and overthinking the relationship, requires lot of closeness.

In my case I am mainly avoidant, and I realised that my ex-girlfriend was anxious. And funny enough, it seems the statistics say this is the common common couple because there are few “secure” in the market and relationships between members of the same group are really uncommon. I actually laughed at this! But I think it is quite true.

The goal is not becoming overnight a secure person but to communicate needs from each side to make the gap smaller.

And from other side, people evolve, change for good and bad. So if you are secure doesnt mean you are always going to be secure, if you attachment fires in a weird way to you can end in a bad situation.

While reading this, I was analyzing myself and my former relationship and was funny how many things started to make sense.

Another thing, attachment is not love. That was a relief. Before my former relationship, I got hit by another person and that made me feel like a puppet, I felt like nothing and I hit rock bottom. But that helped me to work on myself seriously. And this can happen to anybody…

And bad attachments can be difficult to break…

Although, this is not just extremes. I think I have been secure in several points but now I have understand myself better and I think I would act better in a new relationship.

As well, this knowledge helps you to filter potential partners or actual ones. So it can help you to improve your relationship.

At the end of the day, (as usual, I am always trying to find the universal truth in books), everything is reduced to communication. Express your needs openly. Make the relationships a two way street that goes to places.

Arroz Negro

This is a dish that I thought I would never taste neither cook as always saw it with more than squid. Until I went to Galicia with friends and one day we ate arroz negro in a restaurant. I didnt see anything that could give me an allergic attack, although I wondered later on the day if they had used fish stock… but I survived 🙂

So based on that experience, I decided to try it myself at some point. And that was today. I found a video that matched my expectations of using only squid. I bought a couple of things I missed (nothing special) and already had the squid ink I bought online.

Ingredients:

  • 400g frozen squid rings
  • 1-2 tsp of squid ink (or more)
  • 1 bunch of spring onions chopped
  • 1 pepper chopped: I used an orange one.
  • 2 cloves of garlic chopped (I forgot to add it!)
  • 2 tsp of tomate paste
  • 500m of boiling water with a vegetable stock cube
  • 200g aprox (or a bit more) paella rice
  • 1-2 tsp of turmeric
  • salt

Process:

  • In a hot paella dish, drizzle a bit of olive oil. Add the frozen squid rings. Add a pinch of salt.
  • Keep stirring until you have crust in the bottom of the dish. Not burn!!! Drop the heat to medium-low.
  • Add the spring onions and pepper. Mix continuosly, dont allow to burn!
  • Add the tomate paste and mix.
  • Add the rice and mix well for 1 minute or so. Dont allow to burn!
  • Add the vegetable stock with the boiling water. Add a pinch of salt.
  • Add the squid ink with a bit of boiling water to be sure it is not solid.
  • Be sure the paella dish is completely black (In my case I should have added 1 more tsp of ink)
  • Add the turmeric and mix. Taste it! Dont move the rice any more after this.
  • Increase heat to high for 5 minutes aprox. Be sure you move the paella dish to be sure the heat is spread out evenly so the rice is cooked everywhere.
  • Drop the heat to medium.
  • Wait until most of the water is evaporated. With a tsp, try a bit of the rice to be sure it is cooked. You should be able to scratch the bottom and get the extra flavour!
  • Remove from heat, and let it cool for a minute. Ready to eat!

Garlic Mayo

  • 200ml sunflower oil
  • 1 egg
  • 2 chopped garlic cloves
  • salt
  • 1 tbsp of vinegar
  • 1/4 lemon juice

Process:

  • Put all ingredients in a tall glass and use a hand blender.
  • Blend and taste! Need salt? Lemon?
  • Put in a bowl and to the fridge

For my first time, really happy, better than I expected! Just add more ink next time 🙂

Gazpacho

This is nothing new. I have made gazpacho for several years, it always taste nice but somehow I felt it wasnt as good as the ones I tried back home. And to be honest, I never bothered looking for a video…. I followed kind of the recipe from Simone Ortega.

But yesterday, I did my best by far!!! The difference, just three super ripe and juicy tomatoes!!! They filled nearly half of my jar of the blending machine with juice once I crashed them a bit… So this is just a note for the next time. Buy good tomates, they are a bit more expensive, but they are worth every f* penny Mazinger.

Ingredients:

  • 3 super ripe/juicy tomatoes. Peel them
  • 1 red pepper, try to peel it
  • 1 green pepper, try to peel it
  • 1 onion
  • 1 cucumber, peel it.
  • 2-3 cloves of garlic.
  • salt + pepper
  • 1-2 tbs of vinegar
  • 100ml olive oil (aprox)
  • a bit of paprika
  • splash of water (optional- not necessary with good tomatoes)

Process:

  • Put everything in the blender. Mix until everything is smooth.
  • Taste it !!! Needs a bit more salt? olive oil?
  • Put the jar in the fridge.

Enjoy it chilled! (or add an ice cube)

Jay Pad Thai

Some months ago had dinner with a friend in a Thai restaurant. I had Jay Pad Thai (tofu). And it was super tasty! so I had to try at some point.

As far as I can find, the ingredients are:

Wok noodles, tamarind sauce (tamarid pulp + palm sugar + dark soy sauce, etc), beansprouts, fried shallot, garlic chives, peanuts & lime, Wok broccoli, courgette, green beans & tofu.

But at the end I tried this video with several changes…

Ingredients:

  • Tamarind paste: tamarid pulp + grated palm sugar + dark soy sauce (I didnt use fish sauce)
  • Block of firm tofu (smoked optional) 250g
  • soy sauce
  • rice noddles + boiling water
  • 1 big onion (better if you have shallots)
  • 3 sliced garlic cloves.
  • optional: fine chopper ginger (I didnt have that thai pepper)
  • 3 eggs
  • Cauliflower and broccoli (didnt have Chinese chives neither beansprouts…)
  • Crashed peanuts
  • Lime

Process:

  • Cover the noddles with boiling water and set aside
  • With some boiling water, mix the tamarind paste until it is a cream
  • Add the grated palm sugar and dark say sauce to the tamarind cream and mix well.
  • As the mix has tamarind pulp, pass it through a strainer using a spoon so you a sauce without solids. Taste it! Set aside.
  • In a hot wok with some olive oil. Add the tofu, cook until golden. Add a bit of soy sauce.
  • Add the onion, fry until soften
  • Add sliced garlic and ginger. Cook for a minute, dont burn it!
  • Add noddles and tamarind sauce, mix all well.
  • In the wok, set aside a bit the noodles and the beaten eggs. Cook for a bit the eggs and then mix with the noddles.
  • Add the cauliflower and broccoli. Mix well.
  • Remove the wok from the heat, add the peanuts and and squeeze a lime.

The picture is from two days after and although doesnt look great, it is tasty (with room for improvement)

Dune3: Children of Dune

Just finished the third book fo Dune. At some points was quite engaging about all the conspirations, unexpected events, etc. But all the dialogs about the dreams, mixing souls, pass/future were a bit dull as they looked like repetitive. Looking for the next one but I am bit concerned as I guess a bit the next plot…

Tzatziki

This is a sauce that I want to try to do more often. It is very tasty and easy recipe. Extra: you eat more cucumber. I forgot (again) dill 😛

Ingredients

  • 500g creamy yogurt
  • 1 cucumber
  • 2 tbs white wine vinegar
  • 1 clove garlic + 3 tbs olive oil
  • salt + pepper
  • dill

Process

  • Peel and grate the cucumber.
  • Add a 1 tsp of salt and 1 tbs of vinegar. Rest aside
  • In a mortar, put the clove of garlic and oil. Crash it until you garlic is blended with the oil.
  • Add the garlic oil to the yogurt and mix. Add salt and pepper
  • Strain the cucumber with a cheese cloth or similar. Remove most water but dont dry it out!
  • Add the cucumber to the yogurt. Mix well.
  • Add the fresh dill. Taste!!!

without dill 🙁

And tasted good! As the video says, the key is the vinegar.

PD: tziki