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  • VSFTPD Unable to set write permissions on folder

    - by Frank Astin
    I've just set up my first FTP server with VSFTPD on cent os . I can connect to it fine using a user in the group ftp-users but I get read only access . I've tried several different CHMOD codes on the folder (even 777) all to no avail . This is the tutorial I used to set up the server http://tinyurl.com/73pyuxz hopefully you'll be able to see something I missed. Thanks in advance . Requested Config File : # Example config file /etc/vsftpd/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=NO # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. #anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. #anon_mkdir_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd whith two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES

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  • vsftpd not allowing uploads. 550 response

    - by Josh
    I've set vsftpd up on a centos box. I keep trying to upload files but I keep getting "550 Failed to change directory" and "550 Could not get file size." Here's my vsftpd.conf # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=YES # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES anon_other_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=NO # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd whith two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES log_ftp_protocol=YES banner_file=/etc/vsftpd/issue local_root=/var/www guest_enable=YES guest_username=ftpusr ftp_username=nobody

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  • Centos 6.3 vsftp unable to upload file to apache webserver

    - by user148648
    I am new to Centos, I did work with Sun Solaris and upload files to Apache web server before. I create an end user account and manage to ftp using command prompt to the server, error message is '226 Transfer Done (but failed to open directory). Content of my vsftpd.conf as below # Example config file /etc/vsftpd/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=YES # ** may need to comment it back # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) #local_umask=022 local_umask=077 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. anon_upload_enable=YES # *** maybe to comment it back!!! # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES # ** may need to comment it back!!! # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. ascii_upload_enable=YES ascii_download_enable=YES # # You may fully customise the login banner string: ftpd_banner=Warning, only for authorize login. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). chroot_local_user=YES chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list local_root=/var/www # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd with two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES

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  • vsftpd not allowing uploads. 550 response.

    - by Josh
    I've set vsftpd up on a centos box. I keep trying to upload files but I keep getting "550 Failed to change directory" and "550 Could not get file size." Here's my vsftpd.conf # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=YES # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES anon_other_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=NO # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd whith two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES log_ftp_protocol=YES banner_file=/etc/vsftpd/issue local_root=/var/www guest_enable=YES guest_username=ftpusr ftp_username=nobody

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  • local user cannot access vsftpd server

    - by Zloy Smiertniy
    I'm currently running a vsftpd server and I added the necessary configurations in vsftpd.conf so that local users can use clients like FileZilla to manage their homes in a server. I found out that only users in the sudoers list access without a problem only they can't download the files, but users that are not sudoers cannot even access their homes from a client but they can access by a web browser using the FTP protocol and they can only access their home directories (as intented) Im running a fedora 14 on my server and my vsftpd.conf looks like this: # Example config file /etc/vsftpd/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=NO # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. #anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. #anon_mkdir_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. ascii_upload_enable=YES ascii_download_enable=YES # # You may fully customise the login banner string: ftpd_banner=Welcome to GAMBITA FTP service # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). chroot_local_user=YES chroot_list_enable=YES # (default follows) chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd with two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES use_localtime=YES Anyone has an idea of what might be happening? Nothing concerning vsftpd is written in any log

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  • Mac sees mangled filenames from Linux SAMBA share

    - by me2
    Certain filenames in my SAMBA shares from Linux are not getting transmitted properly. It's certain files in certain folders and it doesn't affect all folders or all files within a single folder. I can find no discerning pattern to the mangling but hoping that this is a known problem. No amount of reboot, restart, etc. will fix this problem. The filenames, when they get mangled, all end up in this form: 0JY4B3~H.M4V 0MBS1O~M.M4V 0NKDX9~R.M4V 0O0ZTA~A.M4V These are MPEG4 files. The extension remains intact. Any ideas?

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  • Troubles doing transparent proxy for virtual machines

    - by Dan H
    Hi iptables gurus. First here is the basic topology: Internet | Gateway | Workstation---eth0---virbr0 | +-----+-----+ | | | vm1 vm2 vm3 I need to test a traffic analyzer running on my workstation, listening on some port (say 8990) on eth0. The rule [I think] I want is "any packets leaving virbr0 going anywhere to port 80 must instead go to port 8990 on eth0". My software running on port 8990 does its own check of the NAT packet mangling to push the packets through after it inspects them. I've been banging my head on this, with different variants of: iptables -t nat -A PREROUTING -i virbr0 -p tcp --dport 80 -j DNAT \ --to 10.0.0.10:8990 And I've tried the more generic method of using the mangle table with --set-mark and ip rule add fwmark, but I'm not getting it. I guess what's confusing me is that everything runs on the same box. Thanks for any guidance.

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  • How to design a C / C++ library to be usable in many client languages?

    - by Brian Schimmel
    I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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  • I never really understood: what is Application Binary Interface (ABI)?

    - by claws
    I never clearly understood what is an ABI. I'm sorry for such a lengthy question. I just want to clearly understand things. Please don't point me to wiki article, If could understand it, I wouldn't be here posting such a lengthy post. This is my mindset about different interfaces: TV remote is an interface between user and TV. It is an existing entity but useless (doesn't provide any functionality) by itself. All the functionality for each of those buttons on the remote is implemented in the Television set. Interface: It is a "existing entity" layer between the functionality and consumer of that functionality. An, interface by itself is doesn't do anything. It just invokes the functionality lying behind. Now depending on who the user is there are different type of interfaces. Command Line Interface(CLI) commands are the existing entities, consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: commands consumer: user Graphical User Interface(GUI) window,buttons etc.. are the existing entities, again consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: window,buttons etc.. consumer: user Application Programming Interface(API) functions or to be more correct, interfaces (in interfaced based programming) are the existing entities, consumer here is another program not a user. and again functionality lies behind this layer. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: functions, Interfaces(array of functions). consumer: another program/application. Application Binary Interface (ABI) Here is my problem starts. functionality: ??? existing entities: ??? consumer: ??? I've wrote few softwares in different languages and provided different kind of interfaces (CLI, GUI, API) but I'm not sure, if I ever, provided any ABI. http://en.wikipedia.org/wiki/Application_binary_interface says: ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; Other ABIs standardize details such as the C++ name mangling,[2] . exception propagation,[3] and calling convention between compilers on the same platform, but do not require cross-platform compatibility. Who needs these details? Please don't say, OS. I know assembly programming. I know how linking & loading works. I know what exactly happens inside. Where did C++ name mangling come in between? I thought we are talking at the binary level. Where did languages come in between? anyway, I've downloaded the [PDF] System V Application Binary Interface Edition 4.1 (1997-03-18) to see what exactly it contains. Well, most of it didn't make any sense. Why does it contain 2 chapters (4th & 5th) which describe the ELF file format.Infact, these are the only 2 significant chapters that specification. Rest of all the chapters "Processor Specific". Anyway, I thought that it is completely different topic. Please don't say that ELF file format specs are the ABI. It doesn't qualify to be Interface according to the definition. I know, since we are talking at such low level it must be very specific. But I'm not sure how is it "Instruction Set Architecture(ISA)" specific? Where can I find MS Window's ABI? So, these are the major queries that are bugging me.

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  • How to prepare for a programming competition? Graphs, Stacks, Trees, oh my! [closed]

    - by Simucal
    Last semester I attended ACM's (Association for Computing Machinery) bi-annual programming competition at a local University. My University sent 2 teams of 3 people and we competed amongst other schools in the mid-west. We got our butts kicked. You are given a packet with about 11 problems (1 problem per page) and you have 4 hours to solve as many as you can. They'll run your program you submit against a set of data and your output must match theirs exactly. In fact, the judging is automated for the most part. In any case.. I went there fairly confident in my programming skills and I left there feeling drained and weak. It was a terribly humbling experience. In 4 hours my team of 3 people completed only one of the problems. The top team completed 4 of them and took 1st place. The problems they asked were like no problems I have ever had to answer before. I later learned that in order to solve them some of them effectively you have to use graphs/graph algorithms, trees, stacks. Some of them were simply "greedy" algo's. My question is, how can I better prepare for this semesters programming competition so I don't leave there feeling like a complete moron? What tips do you have for me to be able to answer these problems that involve graphs, trees, various "well known" algorithms? How can I easily identify the algorithm we should implement for a given problem? I have yet to take Algorithm Design in school so I just feel a little out of my element. Here are some examples of the questions asked at the competitions: ACM Problem Sets Update: Just wanted to update this since the latest competition is over. My team placed 1st for our small region (about 6-7 universities with between 1-5 teams each school) and ~15th for the midwest! So, it is a marked improvement over last years performance for sure. We also had no graduate students on our team and after reviewing the rules we found out that many teams had several! So, that would be a pretty big advantage in my own opinion. Problems this semester ranged from about 1-2 "easy" problems (ie bit manipulation, string manipulation) to hard (graph problems involving fairly complex math and network flow problems). We were able to solve 4 problems in our 5 hours. Just wanted to thank everyone for the resources they provided here, we used them for our weekly team practices and it definitely helped! Some quick tips that I have that aren't suggested below: When you are seated at your computer before the competition starts, quickly type out various data structures that you might need that you won't have access to in your languages libraries. I typed out a Graph data-structure complete with floyd-warshall and dijkstra's algorithm before the competition began. We ended up using it in our 2nd problem that we solved and this is the main reason why we solved this problem before anyone else in the midwest. We had it ready to go from the beginning. Similarly, type out the code to read in a file since this will be required for every problem. Save this answer "template" someplace so you can quickly copy/paste it to your IDE at the beginning of each problem. There are no rules on programming anything before the competition starts so get any boilerplate code out the way. We found it useful to have one person who is on permanent whiteboard duty. This is usually the person who is best at math and at working out solutions to get a head start on future problems you will be doing. One person is on permanent programming duty. Your fastest/most skilled "programmer" (most familiar with the language). This will save debugging time also. The last person has several roles between assessing the packet of problems for the next "easiest" problem, helping the person on the whiteboard work out solutions and helping the person programming work out bugs/issues. This person needs to be flexible and be able to switch between roles easily.

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  • Site failing randomly - could it be Cloudflare or something weird in the JS?

    - by James
    I've been working on a simple site that uses javascript to fade through some fullscreen background images as well as some other simple animations. I've tested the site on Chrome, Safari, FF and Opera on OSX, IE8+ on Win7 and Chrome & FF on Ubuntu and everything looks as I'd expect it to. However, I've had reports of the site failing to load (stops at the stage where the background fades up) on Safari and Chrome on OSX and Win. I can't replicate this on any setup so I'm finding it impossible to troubleshoot. Google's instant preview shows the site fine as does most of the options at browsershots.org so I'm really scratching my head. I'm running the site's traffic through Cloudflare and I'm wondering whether anyone can see (or knows from other sites) why Cloudflare might be mangling the JS or causing a problem somehow (I don't get any errors in the JS error console). Of course, if you can replicate the problem on your machine and can suggest an area to look at that would be amazing but I'm hoping that, like me, you don't see any problem with the site! Here's the site: http://www.bighornrevelstoke.com Thanks, James

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  • What is the most concise, unambiguous syntax for operator associated methods (for overloading etc.) that doesn't pollute the namespace?

    - by Doug Treadwell
    Python tends to add double underscores before its built-in or overloadable operator methods, like __add(), whereas C++ requires declaring overloaded operators as operator + (Thing& thing) { /* code */ } for example. Personally I like the operator syntax because it seems to be more explicit and keeps these operator overloading methods separated from other methods without introducing weird prefix notation. What are your thoughts? Also, what about the case of built-in methods that are needed for the programming language to work properly? Is name mangling (like adding __ prefix or sys or something) the best solution here? What do you think about having another type of method declaration, like ... "system method" for lack of creativity at the moment. So there would be two kinds of declarations: int method_name() { ... } system int method_name() { ... } ... and the call would need to be different to distinguish between them. obj.method_name(); vs obj:method_name(); perhaps, assuming a language where : can be unambiguously used in this situation. obj.method_name() vs obj.(system method_name)() Sure, the latter is ugly, but the idea is to make the common case simple and system stuff should be kept out of the way. Maybe the Objective-C notation of method calls? [obj method_name]? Are there more alternatives? Please make suggestions.

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  • c# How to Verify Signature, Loading PUBLIC KEY From PEM file?

    - by bbirtle
    I'm posting this in the hope it saves somebody else the hours I lost on this really stupid problem involving converting formats of public keys. If anybody sees a simpler solution or a problem, please let me know! The eCommerce system I'm using sends me some data along with a signature. They also give me their public key in .pem format. The .pem file looks like this: -----BEGIN PUBLIC KEY----- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDe+hkicNP7ROHUssGNtHwiT2Ew HFrSk/qwrcq8v5metRtTTFPE/nmzSkRnTs3GMpi57rBdxBBJW5W9cpNyGUh0jNXc VrOSClpD5Ri2hER/GcNrxVRP7RlWOqB1C03q4QYmwjHZ+zlM4OUhCCAtSWflB4wC Ka1g88CjFwRw/PB9kwIDAQAB -----END PUBLIC KEY----- Here's the magic code to turn the above into an "RSACryptoServiceProvider" which is capable of verifying the signature. Uses the BouncyCastle library, since .NET apparently (and appallingly cannot do it without some major headaches involving certificate files): RSACryptoServiceProvider thingee; using (var reader = File.OpenText(@"c:\pemfile.pem")) { var x = new PemReader(reader); var y = (RsaKeyParameters)x.ReadObject(); thingee = (RSACryptoServiceProvider)RSACryptoServiceProvider.Create(); var pa = new RSAParameters(); pa.Modulus = y.Modulus.ToByteArray(); pa.Exponent = y.Exponent.ToByteArray(); thingee.ImportParameters(pa); } And then the code to actually verify the signature: var signature = ... //reads from the packet sent by the eCommerce system var data = ... //reads from the packet sent by the eCommerce system var sha = new SHA1CryptoServiceProvider(); byte[] hash = sha.ComputeHash(Encoding.ASCII.GetBytes(data)); byte[] bSignature = Convert.FromBase64String(signature); ///Verify signature, FINALLY: var hasValidSig = thingee.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), bSignature);

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  • How to parse nagios status.dat file?

    - by daniels
    I'd like to parse status.dat file for nagios3 and output as xml with a python script. The xml part is the easy one but how do I go about parsing the file? Use multi line regex? It's possible the file will be large as many hosts and services are monitored, will loading the whole file in memory be wise? I only need to extract services that have critical state and host they belong to. Any help and pointing in the right direction will be highly appreciated. LE Here's how the file looks: ######################################## # NAGIOS STATUS FILE # # THIS FILE IS AUTOMATICALLY GENERATED # BY NAGIOS. DO NOT MODIFY THIS FILE! ######################################## info { created=1233491098 version=2.11 } program { modified_host_attributes=0 modified_service_attributes=0 nagios_pid=15015 daemon_mode=1 program_start=1233490393 last_command_check=0 last_log_rotation=0 enable_notifications=1 active_service_checks_enabled=1 passive_service_checks_enabled=1 active_host_checks_enabled=1 passive_host_checks_enabled=1 enable_event_handlers=1 obsess_over_services=0 obsess_over_hosts=0 check_service_freshness=1 check_host_freshness=0 enable_flap_detection=0 enable_failure_prediction=1 process_performance_data=0 global_host_event_handler= global_service_event_handler= total_external_command_buffer_slots=4096 used_external_command_buffer_slots=0 high_external_command_buffer_slots=0 total_check_result_buffer_slots=4096 used_check_result_buffer_slots=0 high_check_result_buffer_slots=2 } host { host_name=localhost modified_attributes=0 check_command=check-host-alive event_handler= has_been_checked=1 should_be_scheduled=0 check_execution_time=0.019 check_latency=0.000 check_type=0 current_state=0 last_hard_state=0 plugin_output=PING OK - Packet loss = 0%, RTA = 3.57 ms performance_data= last_check=1233490883 next_check=0 current_attempt=1 max_attempts=10 state_type=1 last_state_change=1233489475 last_hard_state_change=1233489475 last_time_up=1233490883 last_time_down=0 last_time_unreachable=0 last_notification=0 next_notification=0 no_more_notifications=0 current_notification_number=0 notifications_enabled=1 problem_has_been_acknowledged=0 acknowledgement_type=0 active_checks_enabled=1 passive_checks_enabled=1 event_handler_enabled=1 flap_detection_enabled=1 failure_prediction_enabled=1 process_performance_data=1 obsess_over_host=1 last_update=1233491098 is_flapping=0 percent_state_change=0.00 scheduled_downtime_depth=0 } service { host_name=gateway service_description=PING modified_attributes=0 check_command=check_ping!100.0,20%!500.0,60% event_handler= has_been_checked=1 should_be_scheduled=1 check_execution_time=4.017 check_latency=0.210 check_type=0 current_state=0 last_hard_state=0 current_attempt=1 max_attempts=4 state_type=1 last_state_change=1233489432 last_hard_state_change=1233489432 last_time_ok=1233491078 last_time_warning=0 last_time_unknown=0 last_time_critical=0 plugin_output=PING OK - Packet loss = 0%, RTA = 2.98 ms performance_data= last_check=1233491078 next_check=1233491378 current_notification_number=0 last_notification=0 next_notification=0 no_more_notifications=0 notifications_enabled=1 active_checks_enabled=1 passive_checks_enabled=1 event_handler_enabled=1 problem_has_been_acknowledged=0 acknowledgement_type=0 flap_detection_enabled=1 failure_prediction_enabled=1 process_performance_data=1 obsess_over_service=1 last_update=1233491098 is_flapping=0 percent_state_change=0.00 scheduled_downtime_depth=0 } It can have any number of hosts and a host can have any number of services.

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  • (Enterprise GlassFish v3 build 11) Communication link problem (MySQL DB)

    - by user312853
    I get a communication link failure while application tries to establish a connection with DB. [#|2010-04-08T20:09:57.825+0300|SEVERE|glassfish3.0|javax.enterprise.system.std.com.sun.enterprise.v3.services.impl|_ThreadID=24;_ThreadName=Thread-1;|Cannot connect to database server = com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.|#] Precisely at this string: Statement s = conn.createStatement(); where conn is defined as follows: private static java.sql.Connection conn; For this app I have set a connection pool with default parameters and currently it (app) uses both JPA and direct JDBC queries. Recreation of connection pool gave nothing, connection pool ping gave next message: Ping Connection Pool for pool is Failed. Ping failed Exce ption - Connection could not be allocated because: Communications lin k failure%%%EOL%%%%%%EOL%%%The last packet sent successfully to the s erver was 0 milliseconds ago. The driver has not received any packets from the server. Please check the server.log for more details.%%%EOL %%%Ping failed Exception - Connection could not be allocated because: Communications link failure and flushing the connection pool gave: com.sun.enterprise.admin.cli.CommandException: remote failure: Failed to flush connection pool ... However I can connect to the database from a terminal. Besides I have the same app working on my local machine with identical connection pool settings. Any one has an idea on whats going on or how to solve the trouble?

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  • Google app engine issue 777 particular solution?

    - by Niklas R
    I use 64.202.189.170 (godaddy) for a HTTP access to a www...on google app engine like GAE issue 777 so that a blank subdomain forwards to www.domain I get the blank to respond by output "This website is temporarily unavailable, please try again later. " There's info about this issue here http://knol.google.com/k/google-apps-discussion-group#view and here http://code.google.com/p/googleappengine/issues/detail?id=777 Since I managed to do it with a .com domain (The godaddy DNS hosted gralumo.com correctly responds to www..) I now want to do it with an off-site DNS managed domain getting the following info about servers: $ ping montao.com.br PING montao.com.br (64.202.189.170) 56(84) bytes of data. 64 bytes from pwfwd-v01.prod.mesa1.secureserver.net (64.202.189.170): icmp_seq=1 ttl=113 time=188 ms 64 bytes from pwfwd-v01.prod.mesa1.secureserver.net (64.202.189.170): icmp_seq=2 ttl=113 time=188 ms ^C --- montao.com.br ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1001ms rtt min/avg/max/mdev = 188.459/188.692/188.926/0.493 ms ubuntu@ubuntu:~$ ping www.montao.com.br PING ghs.l.google.com (74.125.43.121) 56(84) bytes of data. 64 bytes from bw-in-f121.1e100.net (74.125.43.121): icmp_seq=1 ttl=56 time=30.2 ms 64 bytes from bw-in-f121.1e100.net (74.125.43.121): icmp_seq=2 ttl=56 time=28.0 ms 64 bytes from bw-in-f121.1e100.net (74.125.43.121): icmp_seq=3 ttl=56 time=24.2 ms ^C --- ghs.l.google.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2003ms rtt min/avg/max/mdev = 24.201/27.522/30.282/2.514 ms So it looks to me these are the same IP numbers whether or not it's off-site DNS. It's just that it works for one domain and not the other. Could it be just resetting the appspot app ie removing and adding it? Can you recommend how to proceed? Thanks in advance

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  • Axis2 attachments are vanishing in the response

    - by Shamik
    I am using axis2 to come up with a basic web service which will get the file name as parameter and produces a response SOAP packet which will have the file attached along with the SOAP. Here is the way I am creating the service code (its simple and inspired by Axis2 sample code) public String getFile(String name) throws IOException { MessageContext msgCtx = MessageContext.getCurrentMessageContext(); File file = new File (name); System.out.println("File = " + name); System.out.println("File exists = " + file.exists()); FileDataSource fileDataSource = new FileDataSource(file); System.out.println("fileDataSource = " + fileDataSource); DataHandler dataHandler = new DataHandler(fileDataSource); System.out.println("DataHandler = " + dataHandler); String attachmentID = msgCtx.addAttachment(dataHandler); System.out.println("attachment ID = " + attachmentID); return attachmentID; } Now The client side code - MessageContext response = mepClient .getMessageContext(WSDLConstants.MESSAGE_LABEL_IN_VALUE); SOAPBody body = response.getEnvelope().getBody(); OMElement element = body.getFirstElement().getFirstChildWithName( new QName("http://service.soapwithattachments.sample","return")); String attachementId = element.getText(); System.out.println("attachment id is " + attachementId); Attachments attachment = response.getAttachmentMap(); DataHandler dataHandler = attachment.getDataHandler(attachementId); Problem is that dataHandler is always null. Though I think at the server side, the file was read and attached along with the SOAP packet. Am I doing something wrong ? EDIT : I have put <parameter name="enableSwA" locked="false">true</parameter> in the axis2.xml file.

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  • JAVA image transfer problem

    - by user579098
    Hi, I have a school assignment, to send a jpg image,split it into groups of 100 bytes, corrupt it, use a CRC check to locate the errors and re-transmit until it eventually is built back into its original form. It's practically ready, however when I check out the new images, they appear with errors.. I would really appreciate if someone could look at my code below and maybe locate this logical mistake as I can't understand what the problem is because everything looks ok :S For the file with all the data needed including photos and error patterns one could download it from this link:http://rapidshare.com/#!download|932tl2|443122762|Data.zip|739 Thanks in advance, Stefan p.s dont forget to change the paths in the code for the image and error files package networks; import java.io.*; // for file reader import java.util.zip.CRC32; // CRC32 IEEE (Ethernet) public class Main { /** * Reads a whole file into an array of bytes. * @param file The file in question. * @return Array of bytes containing file data. * @throws IOException Message contains why it failed. */ public static byte[] readFileArray(File file) throws IOException { InputStream is = new FileInputStream(file); byte[] data=new byte[(int)file.length()]; is.read(data); is.close(); return data; } /** * Writes (or overwrites if exists) a file with data from an array of bytes. * @param file The file in question. * @param data Array of bytes containing the new file data. * @throws IOException Message contains why it failed. */ public static void writeFileArray(File file, byte[] data) throws IOException { OutputStream os = new FileOutputStream(file,false); os.write(data); os.close(); } /** * Converts a long value to an array of bytes. * @param data The target variable. * @return Byte array conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static byte[] toByta(long data) { return new byte[] { (byte)((data >> 56) & 0xff), (byte)((data >> 48) & 0xff), (byte)((data >> 40) & 0xff), (byte)((data >> 32) & 0xff), (byte)((data >> 24) & 0xff), (byte)((data >> 16) & 0xff), (byte)((data >> 8) & 0xff), (byte)((data >> 0) & 0xff), }; } /** * Converts a an array of bytes to long value. * @param data The target variable. * @return Long value conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static long toLong(byte[] data) { if (data == null || data.length != 8) return 0x0; return (long)( // (Below) convert to longs before shift because digits // are lost with ints beyond the 32-bit limit (long)(0xff & data[0]) << 56 | (long)(0xff & data[1]) << 48 | (long)(0xff & data[2]) << 40 | (long)(0xff & data[3]) << 32 | (long)(0xff & data[4]) << 24 | (long)(0xff & data[5]) << 16 | (long)(0xff & data[6]) << 8 | (long)(0xff & data[7]) << 0 ); } public static byte[] nextNoise(){ byte[] result=new byte[100]; // copy a frame's worth of data (or remaining data if it is less than frame length) int read=Math.min(err_data.length-err_pstn, 100); System.arraycopy(err_data, err_pstn, result, 0, read); // if read data is less than frame length, reset position and add remaining data if(read<100){ err_pstn=100-read; System.arraycopy(err_data, 0, result, read, err_pstn); }else // otherwise, increase position err_pstn+=100; // return noise segment return result; } /** * Given some original data, it is purposefully corrupted according to a * second data array (which is read from a file). In pseudocode: * corrupt = original xor corruptor * @param data The original data. * @return The new (corrupted) data. */ public static byte[] corruptData(byte[] data){ // get the next noise sequence byte[] noise = nextNoise(); // finally, xor data with noise and return result for(int i=0; i<100; i++)data[i]^=noise[i]; return data; } /** * Given an array of data, a packet is created. In pseudocode: * frame = corrupt(data) + crc(data) * @param data The original frame data. * @return The resulting frame data. */ public static byte[] buildFrame(byte[] data){ // pack = [data]+crc32([data]) byte[] hash = new byte[8]; // calculate crc32 of data and copy it to byte array CRC32 crc = new CRC32(); crc.update(data); hash=toByta(crc.getValue()); // create a byte array holding the final packet byte[] pack = new byte[data.length+hash.length]; // create the corrupted data byte[] crpt = new byte[data.length]; crpt = corruptData(data); // copy corrupted data into pack System.arraycopy(crpt, 0, pack, 0, crpt.length); // copy hash into pack System.arraycopy(hash, 0, pack, data.length, hash.length); // return pack return pack; } /** * Verifies frame contents. * @param frame The frame data (data+crc32). * @return True if frame is valid, false otherwise. */ public static boolean verifyFrame(byte[] frame){ // allocate hash and data variables byte[] hash=new byte[8]; byte[] data=new byte[frame.length-hash.length]; // read frame into hash and data variables System.arraycopy(frame, frame.length-hash.length, hash, 0, hash.length); System.arraycopy(frame, 0, data, 0, frame.length-hash.length); // get crc32 of data CRC32 crc = new CRC32(); crc.update(data); // compare crc32 of data with crc32 of frame return crc.getValue()==toLong(hash); } /** * Transfers a file through a channel in frames and reconstructs it into a new file. * @param jpg_file File name of target file to transfer. * @param err_file The channel noise file used to simulate corruption. * @param out_file The name of the newly-created file. * @throws IOException */ public static void transferFile(String jpg_file, String err_file, String out_file) throws IOException { // read file data into global variables jpg_data = readFileArray(new File(jpg_file)); err_data = readFileArray(new File(err_file)); err_pstn = 0; // variable that will hold the final (transfered) data byte[] out_data = new byte[jpg_data.length]; // holds the current frame data byte[] frame_orig = new byte[100]; byte[] frame_sent = new byte[100]; // send file in chunks (frames) of 100 bytes for(int i=0; i<Math.ceil(jpg_data.length/100); i++){ // copy jpg data into frame and init first-time switch System.arraycopy(jpg_data, i*100, frame_orig, 0, 100); boolean not_first=false; System.out.print("Packet #"+i+": "); // repeat getting same frame until frame crc matches with frame content do { if(not_first)System.out.print("F"); frame_sent=buildFrame(frame_orig); not_first=true; }while(!verifyFrame(frame_sent)); // usually, you'd constrain this by time to prevent infinite loops (in // case the channel is so wacked up it doesn't get a single packet right) // copy frame to image file System.out.println("S"); System.arraycopy(frame_sent, 0, out_data, i*100, 100); } System.out.println("\nDone."); writeFileArray(new File(out_file),out_data); } // global variables for file data and pointer public static byte[] jpg_data; public static byte[] err_data; public static int err_pstn=0; public static void main(String[] args) throws IOException { // list of jpg files String[] jpg_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo1.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo2.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo3.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo4.jpg" }; // list of error patterns String[] err_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 1.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 2.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 3.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 4.DAT" }; // loop through all jpg/channel combinations and run tests for(int x=0; x<jpg_file.length; x++){ for(int y=0; y<err_file.length; y++){ System.out.println("Transfering photo"+(x+1)+".jpg using Pattern "+(y+1)+"..."); transferFile(jpg_file[x],err_file[y],jpg_file[x].replace("photo","CH#"+y+"_photo")); } } } }

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  • Search XDocument with LINQ with out knowing the Namespace

    - by BarDev
    Is there a way to search a XDocument without knowing the Namespace. I have a process that logs all soap requests and encrypts the sensitive data. I want to find any elements based on name. Something like, give me all elements where the name is CreditCard. I don't care what the namespace is. My problem seems to be with LINQ and requiring a xml namespace. I have other processes that retrieve values from XML, but I know the namespace for these other process. XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml"); XNamespace xNamespace = "http://CompanyName.AppName.Service.Contracts"; var elements = xDocument.Root.DescendantsAndSelf().Elements().Where(d = d.Name == xNamespace + "CreditCardNumber"); But what I really want, is to have the ability to search xml without knowing about namespaces, something like this: XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml"); var elements = xDocument.Root.DescendantsAndSelf().Elements().Where(d = d.Name == "CreditCardNumber") But of course this will not work be cause I do no have a namespace. BarDev

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  • I just don't get AudioFileReadPackets

    - by Eric Christensen
    I've tried to write the smallest chunk of code to narrow down a problem. It's now just a few lines and it doesn't work, which makes it pretty clear that I have a fundamental misunderstanding of how to use AudioFileReadPackets. I've read the docs and other examples online, and apparently I'm just not getting. Could you explain it to me? Here's what this block should do: I've previously opened a file. I want to read just one packet - the first one of the file - and then print it. But it crashes on the AudioFileReadPackets line: AudioFileID mAudioFile2; AudioFileOpenURL (audioFileURL, 0x01, 0, &mAudioFile2); UInt32 *audioData2 = (UInt32 *)malloc(sizeof(UInt32) * 1); AudioFileReadPackets(mAudioFile2, false, NULL, NULL, 0, (UInt32*)1, audioData2); NSLog(@"first packet:%i",audioData2[0]); (For clarity, I've stripped out all error handling.) It's the AFRP line that crashes out. (I understand that the third and fourth argument are useful, and in my "real" code, I use them, but they're not required, right? So NULL in this case should work, right?) So then what's going on? Any guidance would be much appreciated. Thanks.

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  • How to Verify Signature, Loading PUBLIC KEY From PEM file?

    - by bbirtle
    I'm posting this in the hope it saves somebody else the hours I lost on this really stupid problem involving converting formats of public keys. If anybody sees a simpler solution or a problem, please let me know! The eCommerce system I'm using sends me some data along with a signature. They also give me their public key in .pem format. The .pem file looks like this: -----BEGIN PUBLIC KEY----- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDe+hkicNP7ROHUssGNtHwiT2Ew HFrSk/qwrcq8v5metRtTTFPE/nmzSkRnTs3GMpi57rBdxBBJW5W9cpNyGUh0jNXc VrOSClpD5Ri2hER/GcNrxVRP7RlWOqB1C03q4QYmwjHZ+zlM4OUhCCAtSWflB4wC Ka1g88CjFwRw/PB9kwIDAQAB -----END PUBLIC KEY----- Here's the magic code to turn the above into an "RSACryptoServiceProvider" which is capable of verifying the signature. Uses the BouncyCastle library, since .NET apparently (and appallingly cannot do it without some major headaches involving certificate files): RSACryptoServiceProvider thingee; using (var reader = File.OpenText(@"c:\pemfile.pem")) { var x = new PemReader(reader); var y = (RsaKeyParameters)x.ReadObject(); thingee = (RSACryptoServiceProvider)RSACryptoServiceProvider.Create(); var pa = new RSAParameters(); pa.Modulus = y.Modulus.ToByteArray(); pa.Exponent = y.Exponent.ToByteArray(); thingee.ImportParameters(pa); } And then the code to actually verify the signature: var signature = ... //reads from the packet sent by the eCommerce system var data = ... //reads from the packet sent by the eCommerce system var sha = new SHA1CryptoServiceProvider(); byte[] hash = sha.ComputeHash(Encoding.ASCII.GetBytes(data)); byte[] bSignature = Convert.FromBase64String(signature); ///Verify signature, FINALLY: var hasValidSig = thingee.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), bSignature);

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  • MSMQ on Win2008 R2 won’t receive messages from older clients

    - by Graffen
    Hi all I'm battling a really weird problem here. I have a Windows 2008 R2 server with Message Queueing installed. On another machine, running Windows 2003 is a service that is set up to send messages to a public queue on the 2008 server. However, messages never show up on the server. I've written a small console app that just sends a "Hello World" message to a test queue on the 2008 machine. Running this app on XP or 2003 results in absolutely nothing. However, when I try running the app on my Windows 7 machine, a message is delivered just fine. I've been through all sorts of security settings, disabled firewalls on all machines etc. The event log shows nothing of interest, and no exceptions are being thrown on the clients. Running a packet sniffer (WireShark) on the server reveals only a little. When trying to send a message from XP or 2003 I only see an ICMP error "Port Unreachable" on port 3527 (which I gather is an MQPing packet?). After that, silence. Wireshark shows a nice little stream of packets when I try from my Win7 client (as expected - messages get delivered just fine from Win7). I've enabled MSMQ End2End logging on the server, but only entries from the messages sent from my Win7 machine are appearing in the log. So somehow it seems that messages are being dropped silently somewhere along the route from XP or 2003 to my 2008 server. Does anyone have any clues as to what might be causing this mysterious behaviour? -- Jesper

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  • Game login authentication and security.

    - by Charles
    First off I will say I am completely new to security in coding. I am currently helping a friend develop a small game (in Python) which will have a login server. I don't have much knowledge regarding security, but I know many games do have issues with this. Everything from 3rd party applications (bots) to WPE packet manipulation. Considering how small this game will be and the limited user base, I doubt we will have serious issues, but would like to try our best to limit problems. I am not sure where to start or what methods I should use, or what's worth it. For example, sending data to the server such as login name and password. I was told his information should be encrypted when sending, so in-case someone was viewing it (with whatever means), that they couldn't get into the account. However, if someone is able to capture the encrypted string, wouldn't this string always work since it's decrypted server side? In other words, someone could just capture the packet, reuse it, and still gain access to the account? The main goal I am really looking for is to make sure the players are logging into the game with the client we provide, and to make sure it's 'secure' (broad, I know). I have looked around at different methods such as Public and Private Key encryption, which I am sure any hex editor could eventually find. There are many other methods that seem way over my head at the moment and leave the impression of overkill. I realize nothing is 100% secure. I am just looking for any input or reading material (links) to accomplish the main goal stated above. Would appreciate any help, thanks.

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  • Any suggestions for good automated web load testing tool?

    - by fmunkert
    What are some good automated tools for load testing (stress testing) web applications, that do not use record and replay of HTTP network packets? I am aware that there are numerous load testing tools on the market that record and replay HTTP network packets. But these are unsuitable for my purpose, because of this: The HTTP packet format changes very often in our application (e.g. when we optimize an AJAX call). We do not want to adapt all test scripts just because there is a slight change in HTTP packet format. Our test team shall not need to know any internals about our application to write their test scripts. A tool that replays HTTP packets, however, requires the team to know the format of HTTP requests and responses, such that they can adapt details of the replayed HTTP packets (e.g. user name). The automated load testing tool I am looking for should be able to let the test team write "black box" test scripts such as: Invoke web page at URL http://... . First, enter XXX into text field XXX. Then, press button XXX. Wait until response has been received from web server. Verify that text field XXX now contains the text XXX. The tool should be able to simulate up to several 1000 users, and it should be compatible with web applications using ASP.NET and AJAX.

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  • how to continuously send data without blocking?

    - by Donal Rafferty
    I am trying to send rtp audio data from my Android application. I currently can send 1 RTP packet with the code below and I also have another class that extends Thread that listens to and receives RTP packets. My question is how do I continuously send my updated buffer through the packet payload without blocking the receiving thread? public void run() { isRecording = true; android.os.Process.setThreadPriority (android.os.Process.THREAD_PRIORITY_URGENT_AUDIO); int buffersize = AudioRecord.getMinBufferSize(8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT); Log.d("BUFFERSIZE","Buffer size = " + buffersize); arec = new AudioRecord(MediaRecorder.AudioSource.MIC, 8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, buffersize); short[] readBuffer = new short[80]; byte[] buffer = new byte[160]; arec.startRecording(); while(arec.getRecordingState() == AudioRecord.RECORDSTATE_RECORDING){ int frames = arec.read(readBuffer, 0, 80); @SuppressWarnings("unused") int lenghtInBytes = codec.encode(readBuffer, 0, buffer, frames); RtpPacket rtpPacket = new RtpPacket(); rtpPacket.setV(2); rtpPacket.setX(0); rtpPacket.setM(0); rtpPacket.setPT(0); rtpPacket.setSSRC(123342345); rtpPacket.setPayload(buffer, 160); try { rtpSession2.sendRtpPacket(rtpPacket); } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (RtpException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } So when I send on one device and receive on another I get decent audio, but when I send and receive on both I get broken sound like its taking turns to send and receive audio. I have a feeling it could be to do with the while loop? it could be looping around in there and not letting anything else run?

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