Parallel Programing with MPI
... Process groups are ordered sets of processes
Each process is locally uniquely identified via its local
(group-related) process ID or rank
Ordering starts with zero, successive numbering
Global identification of a process via the pair (process
Lab Additions/Suggestions previously done
... • Experimentation with “Smashing the Stack for fun and profit” by Aleph One
• A Real World Exploit imapd
• Common Vulnerabilities Buffer Overrun
• A Contemporary Vulnerability DCOM RPC
• Libsafe – A Stack Buffer Overflow Preventive Measure
• Obtaining Administrator Privileges on Windows using a Buff ...
... Important if your server has
other things to do
For example sending data to
many clients at once
• Send only the data that you
can send immediately
• Send more data when the
connection is ready to take
Why write exploits?
... dll.BaseAddress = 0x77f00000
dll.Address['JMP ESP'] = 0x77F32836
dll.Address['JMP EDI'] = 0x77F2D148
dll.Address['CALL EAX'] = 0x77F1A9DD
dll.Address['JMP [EBX]'] = 0x77F0174A
dll.Address['CALL EBX'] = 0x77F01089
dll.Address['JMP ECX'] = 0x77F05372
dll.Address['JMP [EAX]'] = 0x77F08070
What are Sockets?
... The client code for a datagram socket client is the same as that for a
stream socket with the following differences.
– the socket system call has SOCK_DGRAM instead of SOCK_STREAM as
its second argument & IPPROTO_UDP instead of IPPROTO_TCP as its
– there is no connect() system call
TCP TRANSMISSION CONTROL PROTOCOL INTRODUCTION TO TCP, THE INTERNET'S
... TCP ‘B’ sends a pure window update segment to signal to TCP ‘A’ that the receive window size is now 10000 again (Rx buffer).
Note that a real TCP implementation would not send a window update if the Rx buffer still has reasonable free capacity.
A real TCP implementation would wait for more data to a ...
... • All of them exploited flaws in application programs
• Very common for DoS attacks
1. Netmeeting 2.x by Cult of the Dead Cow
2. NT RAS by Cerberus Information Security
3. Winhlp32 by Cerberus Information Security
4. IISHack by eEye
5. Oracle Web Listener 4.0 by CIS
6. Outlook GMT token ove ...
... Balance memory usage while under memory stress.
Controls on the actual memory usage (not just TCP window size)
So it includes memory used by the socket data structures
The maximum values have to be larger than the BDP
Example: for a BDP of the order of 20MB, we can chose 32MB
... Stack is generic to allow any type of value to be stored
Stack wordStack = new Stack();
Stack numStack = new Stack();
... If the Internet address is equal to INADDR_ANY, any appropriate network
interface will be used; this simplifies application programming in the presence
of multi-homed hosts.
If the port is specified as 0, the Windows Sockets implementation will assign a
unique port to the application with a value be ...
IPv6 Land Speed Record
... R=C*(RTT**2)/2*MSS (where C is the link capacity and MSS is the max segment size). This is not
a real problem for standard traffic on a shared link, but a serious penalty for long distance transfers
of large amount of data.
The TCP stack was designed a long time ago and for much slower networks: fro ...
... • Pure stream-oriented connection, it does not care
about message boundaries
• A TCP connection is full duplex (bidirectional),
so the same socket can be read and written to (cf.
half duplex pipes)
• Provides a checksum that guarantees packet
MPT SP2 v2 - Raven Computers Ltd
... Support for per message spam confidence level
(SCL) ratings and message tagging.
Outlook 2003 uses SmartScreen & SCL to enhance
Linux Multilayer Switchin with LiSA
... incoming interface differs from the tagging on the
outgoing interface 3 .
Although this is what happens most frequently, it's not
the only possible case. For instance, a socket buffer may
have already been passed to one or more generic packet
handlers when it reaches the Switching Engine. And it
An End-to-End Measurement Study of Modern Cellular Data Networks
... instantaneous throughput for cellular data networks. Finally, we investigate how the instantaneous throughput of cellular data networks varies over time and find that it can vary
by as much as two orders of magnitude within a 10-min interval.
4.1 Burstiness of Packet Arrival
In cellular data network ...
Utility-Maximizing Data Dissemination in Socially Selfish
... data injection rates for lower layers to handle; at the network
layer, a relay node strategically decides the next-hop relay for
each data session to be forwarded to; at the MAC layer, the
available spectrum is carefully and dynamically allocated for
transmission between pairs of nodes. All of these ...
Institutionen för systemteknik
... processor. The main objective of this project was to integrate these components into an IP
router with two or more Gigabit Ethernet interfaces.
A working system has been designed and found working. It consists of three main
components, the input module, the output module and a packet buffer. Due to ...
Remi Ando, Tutomu Murase, Masato Oguchi
... Terminal in Wireless LAN
QoS-TCP is likely to guarantee a target bandwidth in mobile
Analysis of performance evaluation results
QoS-TCP cannot defeat competitive TCP in bit error free
IP Telephony Project
... system into your web page…
• Imagine being able to give your customers a
world wide toll-free number…
• IP Telephony enables all that, and more...
Network Lab - Technion
In computer security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites memory in adjacent locations. This is a special case of the violation of memory safety.Buffer overflows can be triggered by inputs that are designed to execute code, or alter the way the program operates. This may result in erratic program behavior, including memory access errors, incorrect results, a crash, or a breach of system security. Thus, they are the basis of many software vulnerabilities and can be maliciously exploited.Programming languages commonly associated with buffer overflows include C and C++, which provide no built-in protection against accessing or overwriting data in any part of memory and do not automatically check that data written to an array (the built-in buffer type) is within the boundaries of that array. Bounds checking can prevent buffer overflows.