Method and apparatus for MSS spoofing
US6327626A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 1998 |
| Grant date | Dec 4, 2001 |
| Priority date | — |
| Expiry date | Sep 15, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L47/36
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A mechanism, referred to as MSS spoofing, intercepts and modifies the MSS value specified in a TCP SYN packet containing a TCP MSS option. As a result, the local TCP protocol stack is "spoofed" (i.e. made to believe) such that it appears to the local stack that the remote station has an MSS value that is different from its actual MSS value. MSS spoofing allows the local TCP protocol stack to use an MSS value that is derived solely from its own MTU. The interface changes the received MSS value to a value that is at least as large as the local MTU before passing the packet up the protocol stack. This forces the TCP protocol stack to use a larger MSS value than it would otherwise use. In this way, the TCP protocol stack always uses a TCP segment size that is based on the MTU of the local interface. The mechanism described herein allows a host using the TCP transport protocol to choose the larger of two unequal MSS values received during MSS negotiation when establishing a connection between two stations. As a result, the determination mechanism of the local MSS value used by the TCP/IP protocol stack is changed to be the larger of two unequal offered MSS values, instead of being the s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.