Amer Networks E5Web GUI - Manual (Page 726)

TCP Option ALTCHKREQ
Determines how cOS Core will handle alternate checksum request options. These options were
initially intended to be used in negotiating for the use of better checksums in TCP. However,
these are not understood by any today's standard systems. As cOS Core cannot understand
checksum algorithms other than the standard algorithm, these options can never be accepted.
The ALTCHKREQ option is normally never seen on modern networks.
Default: StripLog
TCP Option ALTCHKDATA
Determines how cOS Core will handle alternate checksum data options. These options are used
to transport alternate checksums where permitted by ALTCHKREQ above. Normally never seen
on modern networks.
Default: StripLog
TCP Option Con Timeout
Determines how cOS Core will handle connection count options.
Default: StripLogBad
TCP Option Other
Specifies how cOS Core will deal with TCP options not covered by the above settings. These
options usually never appear on modern networks.
Default: StripLog
TCP SYN/URG
Specifies how cOS Core will deal with TCP packets with SYN (synchronize) flags and URG (urgent
data) flags both turned on. The presence of a SYN flag indicates that a new connection is in the
process of being opened, and an URG flag means that the packet contains data requiring urgent
attention. These two flags should not be turned on in a single packet as they are used exclusively
to crash computers with poorly implemented TCP stacks.
Default: DropLog
TCP SYN/PSH
Specifies how cOS Core will deal with TCP packets with SYN and PSH (push) flags both turned on.
The PSH flag means that the recipient stack should immediately send the information in the
packet to the destination application in the computer.
These two flags should not be turned on at the same time as it could pose a crash risk for poorly
implemented TCP stacks. However, some Apple MAC systems implement TCP in a non-standard
way, meaning that they always send out SYN packets with the PSH flag turned on. This is why
cOS Core normally removes the PSH flag and allows the packet through despite the fact that
such packets would be dropped if standards were strictly followed.
Default: StripSilent
Chapter 12: Advanced Settings
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