(Sorry, I don't know exactly should I ask this question here in stackoverflow or other related sites. please move it if isn't appropriate)
There are some unrelated groups of students which each group members produce data together. each member use his credentials to login to the client desktop application and send data to the server. other group members should see new data if they login with their credentials.
The problem comes in when I want to make the client works although there was an error in connection to the server. I don't want to stop them if they couldn't connect to server, so they make data and later will send it to server.
here is the problem, without connecting to the server, how can I make memberships in the client and be sure he really belongs to the group, or how can I know other member has new data in the local machine so his collegues can see it?
I don't want to use another local server, just a remote server and a local machine with database.
If the server is unavailable, the only way to know if a person is in a group is if you have that information stored on the client. Of course, someone could be removed from a group and the (disconnected) client does not know it.
Solving this would depend on how your system is used.
If membership does not change very often, you could use the client-saved membership as long as it is not too old (e.g. use it if it is less than 4 hours old, or some such rule).
Whenever the client re-connects to the server, it should ensure that its local data is refreshed if it older than N-hours
In addition, when the connection is re-established, and the data is sent to the server, the server should check once more. if the user has been removed from a group, the server can reject the data
Related
I need a way to identify whether a given port at a given address is running an instance of Microsoft SQL Server, IBM DB2 Server, or neither, from Python.
My first thought is that I can use Python's telnet library, telnetlib, like this:
import telnetlib
import socket
def checkDBServerType(address, port):
try:
tn = telnetlib.Telnet(address, port)
except socket.error:
return None
tn.write(<something>)
if <something-else> in tn.read_eager():
return "MSSQL"
else:
return "IBMDB2"
The issue is, I have no idea what to send. The user will also be providing my program with a username, password, and database name, so those are also available if that helps.
Also, this is my first post on ServerFault although I've used StackOverflow regularly and SuperUser sometimes. Is this the proper venue for my question, or would it be more appropriate on StackOverflow? (I can't decide if server admin type people or programmer type people would be more likely to be able to help.)
Since you're just looking for a heuristic, I'd say that merely being able to connect to the default port would be a good first cut. So, for instance, if you can connect to TCP 1433, you can reasonably say that that machine is running a default instance of SQL Server. It's not perfect of course (i.e. you could get false positives or false negatives), but it's pretty good. Only you can answer whether it's good enough for you.
You can't simply "talk" to a database server and expect it to tell you what kind of software it's running; there is no standard common protocol to connect to database servers, and although the query language (SQL) is quite standardized, the underlying connection is based on a protocol which is specific to each database system; these protocols are also generally not text-based, thus you can't simply open a socket to a database server and write something on it; also, they are usually never used directly by client applications: every DBMS provides a set of connection libraries which neatly encapsulate them, so that you don't have to understand how to talk to the database server and can focus on actually querying its data.
Your best bet would be to grab the client connection libraries for SQL Server and DB2 and ask each of them to connect to the remote server; whetever one succeeds first will tell you what kind of server is sitting on the remote end.
I have a mssql 2005 and software (that written by visual basic 6) and the software connects to the mssql.(local)
but the problem is that the "sa" user password changes every day!
And the company that write this software does not give us the password.
And the windows authentication does not work and I think that they delete the windows user too.
I searched on the msdn and ... that i found in the LAN, packets from clients were encrypted in SSL type and sent to the mssql and in a specific packet it includes the username and password of the db, and if that user&pass is same with db user&pass it can be full access to db.
I used backtrack & metasploit but it use dictionary for attack but it did not help me .
I used wireshark for finding that specific packet , then i think i found it (99% I sure) but that packet has a lot of unclear characters and i could not find those.
do you think that if i use SSLSTRIP to make a fake certificate then use it between client and server (as a gateway) can i get that? How?
can I use single user mode to add any user to mssql? How?
You are totally approaching this from the wrong angle. You have a software package that goes at extra lengths to prevent access to your data. You problem is the vendor, ditch him. Use a different software, one that has a rational vendor behind it.
Here are the MSDN official, approved, methodology to regain access on a SQL Server that had locked out administrators: Connect to SQL Server When System Administrators Are Locked Out
When I link the Microsoft Access to SQL Server locally, everything works. The second I go to a computer that is on the network, I am not able to open the form I created on the Access database.
I found out that if I open the link, I will get an error. If I choose where the DB through configurations in Access, I get the error again. If I try this a third time, it connects to the database and it is fully linked--I am able to type data into Access and it will store it in the SQL Server database as well.
My question is: How do I get it to connect to the server on the first try? I have to hit "connect" three times which takes about 5 minutes to log in. That isn't very efficient when the people using this program nothing about computers.
Linking Access to SQL Server uses ODBC. Make sure your ODBC settings are correct.
A while ago, I wrote a web-based guestbook application that wrote it's own database.
My code was very amateurish, but, as it was my very first publication, I was very happy with it.
Only about a month after I'd published it did I realize I'd made a huge mistake in the code.
I've only ever connected to a specific named instance of SQL Server, and it occurred to me that, if the SQL Server instance has a different name than the one I specified, it wouldn't work.
So, since my users will probably not know what the name of the instance of SQL Server that's running is, I thought adding a field where the user can specify it would help if they do, but what if they don't?
My answer was to get the local instance, regardless of name.
I tried Data Source=.\local;, Data Source=.; and other variants, but nothing worked.
Any ideas?
A non-named instance is called "default instance" and can be accessed using "Data Source=(local);...".
The only way of knowing which instances are running is by querying the SQL Browser Service, if it's running.
I guess most of your users are running SQL Server Express? If so, the service is called local\SQLEXPRESS. If not, it's local or they've named it themselves. So, I would try local\SQLEXPRESS first, then local. If none works, just throw an exception and ask the user to add it themselves.
ActiveDirectory Server 2003
I am using the ActiveDirectoryMembershipProvider and ADroleProvider. They work great. Until my active directory server restarts in the middle of the day to get updates. (I'm not in charge of the server and can't change this). When this happens, for the five minutes the server is rebooting, my users can't use my website because I've tied my menu to the Role Provider. So, here are my questions:
Is it possible to tell my RoleProvider to use the "next" available ADS? If so, how so that while the initial one reboots, I don't frustrate my users with ADS connection messages?
Should I be using some kind of connection pool that automatically reconnects to the available server? If so, how?
Let's imagine that all my active directory servers go down. Is there a way to keep my web application running? Obviously there are bigger problems if all servers are down, but what I'm after is a possible "disconnected" active directory authentication that will still move forward if the server somehow goes kaput. Is this wise AND possible?
You probably have the server connection string set to "server01.domain.local". If you change it to just "domain.local" you're no longer depending on "server01" being online. Instead you will use the Round Robin feature of Active Directory DNS to get a list of all domain controllers and use one that's online. (I don't think your admins reboot all of the domain controllers at the same time...)
Also try running nslookup domain.local a couple of times in succession in a command prompt to see the order changing.