08-21-2008
From
UDP: the User Datagram Protocol
Quote:
Although UDP provides error checking, it does not do anything to recover from an error. Some implementations of UDP simply discard the damaged segment; others pass the damaged segment to the application with a warning.
So getting the checksum is OS and IP-stack implementation-dependent. BTW: How are you dealing with missing packets? (you are tracking sequence numbers, yes?)
9 More Discussions You Might Find Interesting
1. Programming
Hello sir,,
i m doing network programming in C
could u plzz let me know...at the time of udp checksum calculation does htons() or ntohs() play some role..??
i mean will there be any difference if some values are added in network form and other is in the host form...
Thnx 4 ur time..
... (4 Replies)
Discussion started by: nirucool89
4 Replies
2. UNIX for Advanced & Expert Users
find . \! -type p -exec cksum {} \; >> check.out
Okay i was able to get the checksum of the files of the directory and sub directories..how do I get the list with the checksum and the file permissions and dates in the same file...now this is driving me crazy...can anyone help me with this ? ls... (3 Replies)
Discussion started by: moe458
3 Replies
3. Shell Programming and Scripting
Hi All,
I have spooled some data in a file (a.dat, b.dat etc..) and after that I want to get the size and checksum of spooled file (a.dat, b.dat etc..) in a log file(file_info.log).
By the way I dont want lost the previous output file info(Append data).
View of log file that I want to... (5 Replies)
Discussion started by: ce_emre21
5 Replies
4. IP Networking
Hello
I am communicating with two devices using my computer over UDP protocol. The application is running fine. When I monitored the UDP traffic using Wireshark software, I found that there were too many Checksum errors.
Please find attached the png file showing this error. I am about to... (0 Replies)
Discussion started by: AustinCann
0 Replies
5. UNIX for Advanced & Expert Users
Hai,
I am having one server/client both running in different host in UDP. How can i assure whether the data is recieved properly in client side. I am writing 250 KB in Server and client reading only 150 KB data. I am using select write in server and select read in client also.If i am putting one... (1 Reply)
Discussion started by: andrew.paul
1 Replies
6. Shell Programming and Scripting
hi all i want a script to FTP a file and should generate a quality checksum file
means when I FTP a file from one server to another server it should generate a QC file which should contain timestamp,no.of records in that file
Thanks in advance
saikumar (3 Replies)
Discussion started by: hemanthsaikumar
3 Replies
7. Solaris
I have one utility in VB which generates attached file(circle.14.mdn_range.properties_VB) & i have created other file(circle.14.mdn_range.properties_UTLFILE) having same contents with UTL_FILE(Oracle running on solaris). But checksum is different for both the files with same contents. Can you... (7 Replies)
Discussion started by: siramitsharma
7 Replies
8. Shell Programming and Scripting
Hi, We have an AIX server and have CURL 7.40 installed in it.
We are struggling to perform checksum on the file present on the remote server (AWS). We want to validate the checksum on the file pre and post download to make sure that there is no issue with the file.
We are writing a shell... (0 Replies)
Discussion started by: Sanjay_13
0 Replies
9. UNIX for Beginners Questions & Answers
Hi Folks,
I need a UNIX script which will copy files(Table wise) from source directory to destination directory (Under table directory) and also creates 2 additional files after getting copied to destination directory with extension .pdy and .ldy , . pdy file will be zero byte file should get... (4 Replies)
Discussion started by: Nicks1412
4 Replies
LEARN ABOUT LINUX
udplite
UDPLITE(7) Linux Programmer's Manual UDPLITE(7)
NAME
udplite - Lightweight User Datagram Protocol
SYNOPSIS
#include <sys/socket.h>
sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
DESCRIPTION
This is an implementation of the Lightweight User Datagram Protocol (UDP-Lite), as described in RFC 3828.
UDP-Lite is an extension of UDP (RFC 768) to support variable-length checksums. This has advantages for some types of multimedia transport
that may be able to make use of slightly damaged datagrams, rather than having them discarded by lower-layer protocols.
The variable-length checksum coverage is set via a setsockopt(2) option. If this option is not set, the only difference to UDP is in using
a different IP protocol identifier (IANA number 136).
The UDP-Lite implementation is a full extension of udp(7), i.e., it shares the same API and API behaviour, and in addition offers two
socket options to control the checksum coverage.
Address format
UDP-Litev4 uses the sockaddr_in address format described in ip(7). UDP-Litev6 uses the sockaddr_in6 address format described in ipv6(7).
Socket options
To set or get a UDP-Lite socket option, call getsockopt(2) to read or setsockopt(2) to write the option with the option level argument set
to IPPROTO_UDPLITE. In addition, all IPPROTO_UDP socket options are valid on a UDP-Lite socket. See udp(7) for more information.
The following two options are specific to UDP-Lite.
UDPLITE_SEND_CSCOV
This option sets the sender checksum coverage and takes an int as argument, with a checksum coverage value in the range 0..2^16-1.
A value of 0 means that the entire datagram is always covered. Values from 1-7 are illegal (RFC 3828, 3.1) and are rounded up to
the minimum coverage of 8.
With regard to IPv6 jumbograms (RFC 2675), the UDP-Litev6 checksum coverage is limited to the first 2^16-1 octets, as per RFC 3828,
3.5. Higher values are therefore silently truncated to 2^16-1. If in doubt, the current coverage value can always be queried using
getsockopt(2).
UDPLITE_RECV_CSCOV
This is the receiver-side analogue and uses the same argument format and value range as UDPLITE_SEND_CSCOV. This option is not
required to enable traffic with partial checksum coverage. Its function is that of a traffic filter: when enabled, it instructs the
kernel to drop all packets which have a coverage less than the specified coverage value.
When the value of UDPLITE_RECV_CSCOV exceeds the actual packet coverage, incoming packets are silently dropped, but may generate a
warning message in the system log.
ERRORS
All errors documented for udp(7) may be returned. UDP-Lite does not add further errors.
FILES
/proc/net/snmp - basic UDP-Litev4 statistics counters.
/proc/net/snmp6 - basic UDP-Litev6 statistics counters.
VERSIONS
UDP-Litev4/v6 first appeared in Linux 2.6.20.
BUGS
Where glibc support is missing, the following definitions are needed:
#define IPPROTO_UDPLITE 136
#define UDPLITE_SEND_CSCOV 10
#define UDPLITE_RECV_CSCOV 11
SEE ALSO
ip(7), ipv6(7), socket(7), udp(7)
RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite).
Documentation/networking/udplite.txt in the Linux kernel source tree
COLOPHON
This page is part of release 3.55 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-12-03 UDPLITE(7)