Tuesday, October 03, 2017

The first steps of Catalan fascism

There are videos that perfectly portray Catalan nationalism.What they are, what they have always been. The only thing that has happened is that they have been kept quiet while preparing their coup d'etat. Yesterday I saw this video published by the twitter account of SER Cataluña - a radio statiin -. If he looks like a duck, he walks like a duck and does quack, so is a duck:

Fascistas catalanes from drizzt.blog on Vimeo.

Saturday, December 20, 2008

Some notes about using de MacOS X NAT (Network address traslation),

This evening I have to us the NAT (network address traslation) infrestructres that came with MacOS X. The TCP/IP stack of MacOS X and the network utilities came from FreeBSD. The firewall is ipfw and is actived by default. The command line utility that controlles the firewall is ipfw. Unlike Linux, the nat engine is in user space, implemented in a proccess called natd. There are ipfw rules that select the ip packets and send to natd using the divert mechanism

Sharing your Internet connection

The easy way to share your internet connection is to use the Internet. We excecute de System Preferences application, next click in Sharing and the system show the next configuration pane (in spanish):

internet sharing

Now, we must select the public interface (the one is connected to Internet), in this example the airport and we also must select the private interface (where are the computers you want to access Internet throught NAT). Now, we push the Init button and the NAT is active.

We can see in changes that the GUI have done in the system now. We launch the Terminal Application and execute the ipfw show command. We can see the first rule that divert all traffic to the natd process:

00010  26221  16201955 divert 8668 ip from any to any via en1
02000 264607  23464758 allow ip from any to any via lo*
02010      0         0 deny ip from to any in
02020      0         0 deny ip from any to in
02030      0         0 deny ip from to any in
02040      0         0 deny tcp from any to in
02050 209103  38244907 allow tcp from any to any out
02060 333894 376385236 allow tcp from any to any established
02065      0         0 allow tcp from any to any frag
12190      3       192 deny tcp from any to any
65535   7662    912661 allow ip from any to any

We can also check that the natd is executing in the system:

ibookdrizzt:~ terron$ ps aux|grep natd
root       372   0.0  0.0    27332    580  ??  Ss   12:14AM   0:00.43 /usr/sbin/natd -alias_address -interface en1
ibookdrizzt:~ terron$ 

That natd is done when the packet leave the machine throught the public interface. The return flow of packets, when arrive to the machine providing, are diverted to the natd process. If there is an entry in the translation table, the destination address is rewritten in accordance with the contents of the table.

Setting manual NAT

We want to configure the NAT in the next scenario:

We have a PowerMac G5 connected to a wireless network where there is a wifi router connectd to Internet.The wireless network uses the address range and the PowerMac uses the IP address (interface en1, Airport). Also, the PowerMac is connected an ethernet network and uses the IP address (interface en0). We want that the PowerMac uses NAT to translate all the IP address in the rango to a IP in the range 192.168.1.x, if possible the same IP assignated to the interface en1.

The NAT is done in MacOS X just before the packet leave the network interface. In the previus scheme, the packets go yo Internet via the interface en1. We must configure natd to intercept packets before leave the interface and traslate the source address and source port in case we need it. We must intercept any packet whose source address is in network to any address. We add a rule to the ipfw firewall that select all packet from network 192,.168.2.0/24. In the Terminal application:

ipfw -f flush

ipfw add divert natd all from to any via en1

Warning, the first command, delete all the firewall rules. If we want to keep the current ruleset, we must to insert the rule in the firewall and not use the ipfw -f flush command. We can see the actual rule set using the ipfw show command.

Now, we must run the natd command. This program traslate the source address and port from the packet being natted. The address traslated is called alias and usually is the same of the public interface. We also must use the -v parameter to natd if we want to debug the process because it automatically go to background. In theory, the next command will do the work:

/usr/sbin/natd -v -interface en1

But if we test the configuration, it doesn't work, why?. Because this configuration traslate adequately the packets the leave the machine, but the packets that came back from Internet no.This occurs because the implementation of NAT is a user program, and you must configure the firewall, ipfw, to send the packets back to the process natd. However, in Linux, this is done automatically because it maintains the translation tables in the kernel. In this sceneario the solution is easy, because we can use another alias address and another divert rule to send the traffic:

ifconfig en1 alias

ipfw -f flush

ipfw add divert natd all from to any via en1

ipfw add divert natd all from any to via en1

natd -a


The implementation of NAT using MacOS X isn't very efficient. The need to move packages from the kernel to user mode programs and then again to move to the kernel for transmission makes it slower to complete implementations in the Linux kernel and its NetFilter.

The support of inspection protocols is very limited, only supports FTP and IRC, with the rest of protocols that send information with embebbed ip addresses and ports not supported.


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Tuesday, April 08, 2008

A trip to the Valley of Jerte (Valle del Jerte)

Three weeks ago, my wife and I went to the Jerte's Valley (Valle del Jerte in spanish), in Caceres, during the cherry flowering. The flowering lasts just ten days and the valley is covered in the distinctive white color of the cherry blossoms.

We took the A-5 motorway till Navalmoral de la mata, then we took the EX-1 heading Plasencia, but the GPS guided us throught a local road parallel to the river Tietar till the EX-392 road that took us to Jaraíz de la Vega. It would have been easier to take the EX-392 in Navalmoral de la Mata heading Jaraíz de la Vega or arrive to Plasencia and enter into the valley jerte through the N-110.

From Jaraiz de la Vega we took a road that led us throught the mountains through the villages of Pasarón de la Vega, Arroyomolinos de la Vera, Barrada, Carrera reaching Valdastillas. In this area we began to see the first cherry trees and the side of the mountais were white of cherry blossoms.

Slopes covered with cherry blossoms

One of the villages on the slope of the valley.

As we descend from the side of the mountain, across the road which passes through Valdastillas, to the N-110. We took some pictures of the cherry blossoms

Cherry blossoms

The road descends among the cherry trees

We arrived to the N-110 road and we followed it till Navaconcejo where we tool lunch in a little restaurant. This town is divided by the river Jerte and has a beautiful bridge over it.

Bridge over Jerte in Navaconcejo

Cherry blossoms from Navaconcejo

We took again the car and drive throught the N-110 road till we arrived to Cabezuela del Valle. We left the car and walked down a path that runs parallel to the river Jerte.

The Jerte river, in Cabezuela del Valle.
The town was full of suvenir stores where you can buy the tipical cherry trees and products of the zone.

A small waterfall

After the walk, we took the car again, and following the N-110 we arrived to Tornavacas and we began to drive throught the pass of Tornavacas. We took some pictures of the cherry blossoms before we arrived to the highest part of the pass.

cherry blossoms

cherry trees

cherry trees

From there you can enjoy a beautiful lanscape. Mountais around were snowier than the last time (in spanish) we where in Tornavacas. Two more pictures from out trip. First one you can see the town of Tornavacas and Cabezuela del Valle and the second one you can see all the Valley of Jerte. The pictures are a bit dark because the day was cloudy and you couldn't see all the cherry blossoms.

El Valle del Jerte, desde lo alto de Tornavacas

El Valle del Jerte

We decided to return to Madrid throught Avila. The idea was to follow the N-110 from the Pass of Tornavacas which runs through the towns of Barco de Ávila and Piedrahita, then arrive to Avila and take the A-6 motorway to Madrid. But when we arrived to Barco de Avila, it started to snow abundantly:

The old bridge in the middle of the snowstorm

We arrived to Piedrahita without problems, but the snowstorm was stronger. When we leaved Piedrahita, there was a lot of snow in the road and people drove slowly. We couldn't arrive to the Pass of Villatoro, and the policy shorted the road to people that didn't have tire chains. We returned to Piedrahita, then we toolk the road to Alba the Tormes, from there to Peñaranda de Bracamonte, then to Arevalo where we took the A-6 motorway to Madrid. The snowstorm was heavy, and we took some beautiful pictures when the night arrived.

The road covered with snow

the snow country

You can see all the pictures of the trip in this url.

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Sunday, February 25, 2007

A trip to Portugal: Costa Vicentina and the Southwest of the Alentejo

Two years ago my sister and me went on holiday to the Costa Vicentina and the Southwest of the Alentejo. We have decided to publish some photos of the trip and to tell a little the route that we follow.We were three days during the holidays of the Virgin of August (13,14 and 15),and enjoyed mainly of the magnify beaches of thr zone.We lodged in Casa Alcatruz, a litte hotel that is located in Rogil, a small town that belongs to Aljezur.

We left in the evening from La Antilla (in Huelva, Spain) to Rogil. For us, the route route is all freeway to the border Portuguese, to cross the bridge on the Guadiana in Ayamonte , follow all the freeway until Lagos, and later to go by N-120 road until Rogil.Once we entered the state road - that goes from the end of the freeway to Sines -, they are going away to happen a fishing series of beaches and towns, very animated in this holidays, but without the lots of people that usuallu was in the Algarve in Summer.

Once we arrived at Rogil, and we checked in the hotel, we decided to visit one of beaches of the town. This pretty beach is called Praia Vale do Homes. We left a pair of photos of this beautiful beach. Waters are cold and the sea is scrambled. Clifts, but very beautiful coast. In beach usually there is not much people, with which it is rested and it enjoyed.Here are two photos, first one is the cliffs and the other one is a sunset in the Atlantic Ocean.

Vale do Homes

Sunset in the Ocean

The next day we decided to go to the North. We took the N-120 to the towns of Vila Nova de Mil Fontes and Portocobo. We followed this road until Odemira, later to take the N-393. Vila Nova de Mil Fontes is a small town of the coast, located in the mouth of a river, in such a way that it has a small fluvial beach, and beaches in the south of the opening and others in the north - where it is the town -. Like all beaches of this coast, they are coves with cliff in both sides. Cauntion with the beach of the mouth of the river - we were in that beach - , since the current is usually is
strong - and also the water is cold ;) -.

Vila Nova de Mil Fontes

After lunch, we followed by N-390, to enter by a secondary road and to go to Praia da liha. This is a beach, formed by a cove between cliffs, that enjoys a precious view on Ilha do Pessegueiro.

Ilha do Pesseguiro
Praia da liha

Later we approached the neighbor Porto côvo, a small fishing town of white and blue houses. We left one photo of the town so that you enjoy it. This day gave little more of if, the return way until Rogil, exhausted of the day of beach and drive.

Porto côvo

The second day we went to a precious beach, located in a cove that is acceded by a forest track that is called Praia do Murração. Of all the beaches that I have been in Portugal, this small cove is the one that I like more. It is worth the trouble to arrive: little people, fine sand, cold water, rocks for that it likes to practice scuba,… .To arrive it is necessary to go by the road that go from Aljezur to Vila do Obispo. The forest track starts near this last town, in front of the eolic energy plant.

Praia do Murração

Later, we went to the Praia of Bordeira, and took the lunch in a restaurant near the beach: excelent sea bass to eat :D
Praia da Bordeira

After return to Rogil, we decided to spend the evening in a wild beach, called Praia gives Carriagem. The access to this beach is quite complicated, since it is through a cliff. This causes that it is an almost desert beach, but that is worth the trouble to see, although it is from above, without lowering to the border. After sunset we went to the hotel

Praia da Carriagem
Praia da Carriagem

The last day we went to two beach that there were more people in the zone: The Praia da Arrifana and Praia da Cordoama. But there was a foggy day, and we could see anything.

Praia da Arrifana

And this is all the trip :). This zone os Portugal is beautiful: wild beaches, good food, wonderful sunsets. Enjoy it!

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Gredos's mountains and Iruelas valley

Two weeks ago, my girlfriend and me made a trip to the Gredos's mountains (Sierra de Gredos in spanish), near the town of El Tiemblo and the Toros de Guisando. We left Madrid by the highway M-501 (Carretera de los Pantanos) until San Martín de ValleIglesias. The toros de Guisando are located three kilometers from this town.These sculptures are dated from century IV-III before Christ and it thinks that they were magical protections for the meadows around (you can find more information here and here in spanish).

Toros de Guisando

If we followed the road, we went to the town of el Tiemblo, and we took the road to Avila, in order to arrive at the zone of the dam of the Burguillo, we left the road to Avilla, to cross the dam,and to go for the natural reserve of Valle of Iruelas

This zone is located on the North face of the Mountain range of Gredos, and has a spectacular landscape. We took advantage of to eat in the zone of rural tourism.
rural houses
small chapel

After lunch we followed the forestal road direction to the little town of La Rinconada, to take a rural track that raises towards the port of Casilla. Asphalt paving in first km, can be crossed in until it becomes a forest track only apt for four wheel drive cars. This route fits in a valley, following the course of a brook that ends at the dam of Burguillos. In the port he is noticeable in the maps like a viewpoint, but we didn't had a four wheel drive car to climb to it. The forest of pines that crosses is precious and the tranquillity that is breathed for which the excursion has been being worth the trouble.


We recognize that there are sites in the Mountain range of Gredos that is worth the trouble to explore.

Thursday, September 14, 2006

New blog: The English brother of Icewinddale

Hi everybody. This is the english brother of my blog icewinddale. I have thinking in create a blog in english form weeks. I'm not a native english speaker - my native language is spanish -, but I would like to write some english articles and translate some of my spanish one (specially the holidays and the doc that I have been written for Linux or some other operating systems). I also want to practice my english writing :). Perhaps some of the information that I want to post here can be useful for somebody :)