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  • Network config / gear question

    - by mcgee1234
    I have been tasked with setting up a fairly straightforward rack in a data center (we do not even need a whole rack, but this is the smallest allotment available). In a nutshell, 4 to 6 servers need to be able to reach 2 (maybe 3) vendors. The servers needs to be reachable over the internet. A little more detail - the networks the servers need to reach are inside of the data center, and are "trusted". Connections to these networks will be achieved through intra data center cross connects. It is kind of like a manufacturing line where we receive data from one vendor (burst-able up to 200 Mbits), churn through it on the servers, and then send out data to another vendor (bursts up to 20 Mbits). This series of events is very latency sensitive, so much so that it is common practice not to use NAT or a firewall on these segments (or so I hear). To reach the servers over the internet, I plan to use a site to site VPN. (This part is only relevant as far as hardware selection goes). I have 2 configurations in mind: Cisco 2911 (2921) (with the additional wan ports module) and a layer 2 switch - in this scenario, I would use the router also for VPN. Cisco 3560 layer 3 switch to interconnect the networks inside of the data center and an ASA 5510 (which is total overkill, but the 5505 is not rack mountable) as a firewall for the Wan side (internet) and VPN. I envision the setup to be as follows: Internet - ASA - 3560 Vendors - 3560 - Servers The general idea is that the ASA acts as a firewall and VPN device and the 3560 does all the heavy lifting. The first is a fairly traditional setup but my concern is performance. The second is somewhat unorthodox in that the vendors are directly connected to the layer 3 switch without passing through a firewall. Based on my understanding however, a layer 3 switch will perform substantially better as it will do hardware (ASIC) vs. software switching. (Note that number 2 is a little over the budget, but not unworkable (double negative, ugh)) Since this is my first time dealing with a data center, I am not sure what the IP space is going to look like. I suspect I will retain a block(s) of public IPs, vlan them to individual interfaces for the vendor connections and the servers (which will not reachable from the wan side of course) and setup routing on the switch. So here are my questionss: Is there a substantial performance difference between 1 and 2, i.e. hardware based switching on a layer 3 vs a software base on the 2911? I have trolled the internet and found a lot of Cisco literature, but nothing that I could really use to get a good handle. The vendors we connect to are secure and trusted (famous last words) and as I understand it, it is common practice not to NAT or firewall these connections (because of the aforementioned latency sensitivity). But what what kind of latency are we really talking about if I push the data through a router (or even ASA for that matter)? For our purposes, 5 ms will not kill us, 20 or 30 can be very costly. Others measure in microseconds, but they are out of our league. Is there any issues with using public IPs on a layer 3 switch? I am certainly not married to either of these configs, and I am totally open to any ideas. My knowledge (and I use the term loosely) is largely from books so I welcome any advice / insight. Thanks in advance.

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  • negative values in integer programming model

    - by Lucia
    I'm new at using the glpk tool, and after writing a model for certain integer problem and running the solver (glpsol) i get negative values in some constraint that shouldn't be negative at all: No.Row name Activity Lower bound Upper bound 8 act[1] 0 -0 9 act[2] -3 -0 10 act[2] -2 -0 That constraint is defined like this: act{j in J}: sum{i in I} d[i,j] <= y[j]*m; where the sets and variables used are like this: param m, integer, 0; param n, integer, 0; set I := 1..m; set J := 1..n; var y{j in J}, binary; As the upper bound is negative, i think the problem may be in the y[j]*m parte, of the right side of the inequality.. perhaps something with the multiplication of binarys? or that the j in that side of the constrait is undefined? i dont know... i would be greatly grateful if someone can help me with this! :) and excuse for my bad english thanks in advance!

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  • Seeking recommendations on resolving sporadic network connectivity latency for Notes client

    - by Russell Maher
    I have Domino servers in geographically disperse data centers in the U.S. Sometimes when I open an NSF on one of those servers the connection times out then when I open the NSF again it connects immediately. This has been going on for years and during that time I have upgraded and changed my own internet connection and moved servers to different data centers. Of course I have direct connection documents using fixed IP addresses. When I do a Notes client Trace nothing is out of the ordinary. My business partner experiences the same thing from an entirely different city and different ISP but to the same servers. Never have any trouble connecting to the HTTP server, just over port 1352. Does anyone have any recommendations on a process to determine what is causing this problem?

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  • Best programming based games

    - by Matt Sheppard
    Back when I was at school, I remember tinkering with a Mac game where you programmed little robots in a sort of pseudo-assembler language which could then battle each other. They could move themselves around the arena, look for opponents in different directions, and fire some sort of weapon. Pretty basic stuff, but I remember it quite fondly, even if I can't remember the name. Are there any good modern day equivalents?

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  • Cisco ASA 5505 network route for static IP hosts

    - by TheCapn
    I've configured my internal VLAN using the most basic settings where ports 1-7 are assigned from a pool of addresses in the range 192.168.15.5 - 192.168.15.36. These hosts are given access to the internet and it works great. What I'm trying to set up now is allowing users who are connected to the device and specify their IP (say I connect and request 192.168.15.45) are given internet access and can still work alongside DHCP hosts. Those with a DHCP assigned address are blocked from the internet. Mostly the issue resides in that I am very new to working with the device. I feel that the solution is easy but I'm not looking in the right spots and don't have the correct terminology down to google it. Do I need to define access control lists? Group policies? a new VLAN? The rules that are set up seem to be specific to the entire /24 subnet but when I request a static IP outside of the DHCP range I get blocked from other hosts and the internet.

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  • Monitoring VPN users on my network

    - by Fen0x
    My company runs filters on contents available for browsing and I have to check if everyone is respecting the browsing policies. Recently I have spotted some users activate OpenVPN on their workstations and i have discovered that they connect on port 443 of an external server and then use a proxy to circumvent the company filters. Is there any method to monitor VPN connections on allowed ports or to avoid the connections?

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  • Python programming - Windows focus and program process

    - by Zack
    I'm working on a python program that will automatically combine sets of files based on their names. Being a newbie, I wasn't quite sure how to go about it, so I decided to just brute force it with the win32api. So I'm attempting to do everything with virtual keys. So I run the script, it selects the top file (after arranging the by name), then sends a right click command,selects 'combine as adobe PDF', and then have it push enter. This launched the Acrobat combine window, where I send another 'enter' command. The here's where I hit the problem. The folder where I'm converting these things loses focus and I'm unsure how to get it back. Sending alt+tab commands seems somewhat unreliable. It sometimes switches to the wrong thing. A much bigger issue for me.. Different combination of files take different times to combine. though I haven't gotten this far in my code, my plan was to set some arbitrarily long time.sleep() command before it finally sent the last "enter" command to finish and confirm the file name completing the combination process. Is there a way to monitor another programs progress? Is there a way to have python not execute anymore code until something else has finished?

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  • Does anybody have practice in programming PCMEF - architectures?

    - by Erkki
    PCMEF is an architecture style presented in the book Practical Software Engineering by Maciaszek and Liong. The layers are: P: Presentation C: Controller M: Mediator E: Entity F: Foundation. It is some kind of enchancement compared with MVC - architecture. I recommend it to interactice, data and communicating - oriented purposes. I have programmed it using Visual Prolog. Foundation in my applications is the data model (domains) for the application. PCMEF is like a simulated computer: Presentation is the display, Controller the user interface and event handling, Mediator the internal logic and data highway. Entity is the database or external interfaces and F defines the knowledge. This is a really nice small architecture. Does any other have experiance of it?

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  • Why use constants in programming?

    - by Adam N
    I've just been going back over a bit of C studying using Ivor Horton's Beginning C book. I got to the bit about declaring constants which seems to get mixed up with variables in the same sentence. Just to clarify, what is the difference in specifying constants and variables in C, and really, when do you need to use a constant instead of a variable? I know folks say to use a constant when the information doesn't change during program execution but I can't really think of a time when a variable couldn't be used instead. Thanks

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  • Access MacZFS via network from XBMC

    - by AreusAstarte
    I have a ZFS RAID (zpool with three drives) hooked up to my Mac that I want to share in my LAN so that the XBMC client on my OUYA console hooked up to the television can read the drive and use it to stream my movies and television shows onto the television set. I've searched around for a bit but so far haven't found anything that helped me with it. I know that when connecting to the Mac with SSH I can't just access the drive due to different formatting. What do I have to do so that XBMC will be able to read it? How do I share it?

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  • Network configuration with limited hardware

    - by Pavel
    I have cable internet and I have two PC. One of them has wireless and ethernet, the other pc has ethernet only. Also, I have a dsl modem that has wireless builtin (some common speedstream model). My goal is to connect all of them so that both have internet access. As I understand, I have two options: connect speedstream to the cable and then connect other PC's to speedstream; OR, connect pc with wireless to the cable and then connect the other pc that has ethernet only using ethernet+wireless through speestream. First one seems to be easy, but it doesn't seem to work. What about the other choice? Is it possible to do it?

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  • "for" loop from program 7.6 from Kochan's "Programming in Objective-C"

    - by Mr_Vlasov
    "The sigma notation is shorthand for a summation. Its use here means to add the values of 1/2^i, where i varies from 1 to n. That is, add 1/2 + 1/4 + 1/8 .... If you make the value of n large enough, the sum of this series should approach 1. Let’s experiment with different values for n to see how close we get." #import "Fraction.h" int main (int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Fraction *aFraction = [[Fraction alloc] init]; Fraction *sum = [[Fraction alloc] init], *sum2; int i, n, pow2; [sum setTo: 0 over: 1]; // set 1st fraction to 0 NSLog (@"Enter your value for n:"); scanf ("%i", &n); pow2 = 2; for (i = 1; i <= n; ++i) { [aFraction setTo: 1 over: pow2]; sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; pow2 *= 2; } NSLog (@"After %i iterations, the sum is %g", n, [sum convertToNum]); [aFraction release]; [sum release]; [pool drain]; return 0; } Question: Why do we have to create additional variable sum2 that we are using in the "for" loop? Why do we need "release previous sum" here and then again give it a value that we just released? : sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; Is it just for the sake of avoiding memory leakage? (method "add" initializes a variable that is stored in sum2)

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  • C Programming - Passing a pointer to array

    - by Pedro
    How do I pass a pointer value to an array of the struct; For example, on a txt I have this: John Doe;[email protected];214425532; My code: typedef struct Person{ char name[100]; char email[100]; int phone; }PERSON; int main(){ PERSON persons[100]; FILE *fp; char *ap_name; char *ap_email; char *ap_phone; char line[100]; fp=("text.txt","r"); if(fp==NULL){ exit(1); } else{ fgets(line,100,fp); ap_name=strtok(line,";"); ap_email=strtok(NULL,";"); ap_phone=strtok(NULL,";"); } return 0; } My question is how can I pass the value of ap_name, ap_email, ap_phone to the struct? And, do I need to use all of these pointers?

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  • C programming: hashtable insertion/search

    - by Ricardo Campos
    Hello i have a problem with my hash table its implemented like this: #define HT_SIZE 10 typedef struct _list_t_ { char key[20]; char string[20]; char prevValue[20]; struct _list_t_ *next; } list_t; typedef struct _hash_table_t_ { int size; /* the size of the table */ list_t ***table; /* first */ sem_t lock; } hash_table_t; I have a Linked list with 3 pointers because i want a hash table with several partitions (shards), here is my initialization of my Hash table: hash_table_t *create_hash_table(int NUM_SERVER_THREADS, int num_shards){ hash_table_t *new_table; int j,i; if (HT_SIZE<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the hashtable structure */ new_table = (hash_table_t*)malloc(sizeof(hash_table_t)*HT_SIZE); /* Attempt to allocate memory for the table itself */ new_table->table = (list_t ***)calloc(1,sizeof(list_t **)); /* Initialize the elements of the table */ for(j=0; j<num_shards; j++){ new_table->table[j] = (list_t **)calloc(1,sizeof(list_t *)); for(i=0; i<HT_SIZE; i++){ new_table->table[j][i] = (list_t *)calloc(1,sizeof(list_t )); } } /* Set the table's size */ new_table->size = HT_SIZE; sem_init(&new_table->lock, 0, 1); return new_table; } Here is my search function to search in the hash table list_t *lookup_string(hash_table_t *hashtable, char *key, int shardId){ list_t *list ; int hashval = hash(key); /* Go to the correct list based on the hash value and see if key is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ sem_wait(&hashtable->lock); for(list = hashtable->table[shardId][hashval]; list != NULL; list =list->next) { if (strcmp(key, list->key) == 0){ sem_post(&hashtable->lock); return list; } } sem_post(&hashtable->lock); return NULL; } And my insert function: char *add_string(hash_table_t *hashtable, char *str,char *key, int shardId){ list_t *new_list; list_t *current_list; unsigned int hashval = hash(key); /*printf("|%d|%d|%s|\n",hashval,shardId,key);*/ /* Lock for concurrency */ sem_wait(&hashtable->lock); /* Attempt to allocate memory for list */ new_list = (list_t*)malloc(sizeof(list_t)); /* Does item already exist? */ sem_post(&hashtable->lock); current_list = lookup_string(hashtable, key,shardId); sem_wait(&hashtable->lock); /* item already exists, don't insert it again. */ if (current_list != NULL){ strcpy(new_list->prevValue,current_list->string); strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; sem_post(&hashtable->lock); return new_list->prevValue; } /* Insert into list */ strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; /* Unlock */ sem_post(&hashtable->lock); return new_list->prevValue; } My main class runs some of tests by executing the insertion / reading / delete from the elements of the hash table the problem is when i have more than 4 partitions/shards the tests stop at the first reading element saying it returned the wrong value NULL on the search function, when its less than 4 it runs perfectly well and passes all the tests. You can see my main.c in here if you want to give a look: http://hostcode.sourceforge.net/view/1105 My complete Hash table code: http://hostcode.sourceforge.net/view/1103 And other functions where hash table code is executed: .c file http://hostcode.sourceforge.net/view/1104 .h file http://hostcode.sourceforge.net/view/1106 Thank for you time, i appreciate any help you can give to me this is a college important project that I'm trying to solve and I'm stuck here for 2 days.

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  • a question in NS c programming

    - by bahar
    Hi I added a new patch to my NS and I've seen thise two errors. Does anyone Know what I can do? error: specialization of 'bool std::less<_Tp::operator()(const _Tp&, const _Tp&) const [with _Tp = _AlgorithmTime]' in different namespace from definition of 'bool std::less<_Tp::operator()(const _Tp&, const _Tp&) const [with _Tp = _AlgorithmTime]' and the errors are from this code typedef struct _AlgorithmTime { // Round. int round; // Fase. int fase; // Valore massimo di fase. int last_fase; public: _AlgorithmTime() { round = 0; fase = 0; last_fase = 0; } // Costruttore. _AlgorithmTime(int r, int f, int l) { round = r; fase = f; last_fase = l; } // Costruttore. _AlgorithmTime(const _AlgorithmTime & t) { round = t.round; fase = t.fase; last_fase = t.last_fase; } // Operatore di uguaglianza. bool operator== (struct _AlgorithmTime & t) { return ((t.fase == fase) && (t.round == round)); } // Operatore minore. bool operator < (struct _AlgorithmTime & t) { if (round < t.round) return true; if (round > t.round) return false; if (fase < t.fase) return true; return false; } // Operatore maggiore. bool operator > (struct _AlgorithmTime & t) { if (round > t.round) return true; if (round < t.round) return false; if (fase > t.fase) return true; return false; } void operator++ () { if (fase == last_fase) { round++; fase = 0; return; } fase++; } void operator-- () { if (fase == 0) { round--; fase = last_fase; return; } fase--; } }AlgorithmTime; template< bool std::less::operator()(const AlgorithmTime & t1, const AlgorithmTime & t2)const { if (t1.round < t2.round) return true; if (t1.round t2.round) return false; if (t1.fase < t2.fase) return true; return false; } Thanks

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  • How would I find voluntary programming work?

    - by Ben
    While I look for a job, I'd like to do something useful with my time. I have a feeling there must be schools or charities or other worthy organisations that could use some of my time, but I've no idea how to go about finding them. Is there a marketplace for this kind of thing? I live in the UK.

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  • COM(C++) Programming Tutorials

    - by Deep-B
    Hey guys, I was wondering if there're any good sites that deal with learning C++/COM from the ground up? Looking for something like a crash course (two weeks, and not being hypothetical here). Assume knowledge in standard C/C++, or at least not a complete dummy.

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  • Network Performance issue

    - by qubemarker
    We have three Ubuntu 10.04 servers. One server is a storage server and the other two servers are configured as clients. The storage server has a good amount of capacity and it is integrated with windows Active directory server for Authentication. I am uploading some video files from both clients to the server and when I am uploading data from any one client alone I get about 26 MB/s data transfer rate. When I upload data from both the clients simultaneously I am only getting about 8 MB/s from each client. I have gigabit ethernet cards in all of the servers and a L2 Managed gigabit switch for connectivity. I don’t know why the data transfer rate is decreasing so much in simultaneous read and write. I have tried all of the TCP stack related settings suggested here. Can any assist with getting better read/write performance out of this setup? Any help is appreciated.

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  • How does Object Oriented Programming work?

    - by venom
    Hello, I am not sure about some things in OOP. If I have Class1, which has some private field, for example private Field field1, and make getField1 () { return field1; } then I have some class with constructor public Class2 (Field field) { someMethod(field); } And then I call constructor of Class2 in Class3 like: Class2 cl = new Class2(instanceOfClass1.getField1()); And now the question: Am I working with field1 of instanceOfClass1 in someMethod(field)?

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  • Event driven programming in perl?

    - by TheGNUGuy
    Hey everyone, I'm trying to make a jabber bot and I am having trouble keeping it running while waiting for messages. How do I get my script to continuously run? I have tried calling a subroutine that has a while loop that I , in theory, have set up to check for any messages and react accordingly but my script isn't behaving that way. Here is my source: http://pastebin.com/03Habbvh

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  • Conditional interface programming for iPad?

    - by Fyrian
    Hi everyone! I'm working on an app for the iPad and am a little over my head with one issue. Is it possible to build an app for iPad that uses a function to control which interface layout is displayed? Something like "if these parameters are met, use XIB file "a" else use XIB file "b". I know that's not in any kind of legitimate format, but you get the idea. If this is possible, does anyone know of any tutorials on how to do it or sample code I could look at? Thanks!

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