D-Link DFL-2500 - Manual (Page 307)

13.2. TCP Level Settings
TCPOptionSizes
Verifies the size of TCP options. This function acts in the same way as IPOptionSizes described
above.
Default: ValidateLogBad
TCPMSSMin
Determines the minimum permissible size of the TCP MSS. Packets containing maximum segment
sizes below this limit are handled according to the next setting.
Default: 100 bytes
TCPMSSOnLow
Determines the action taken on packets whose TCP MSS option falls below the stipulated
TCPMSSMin value. Values that are too low could cause problems in poorly written TCP stacks.
Default: DropLog
TCPMSSMax
Determines the maximum permissible TCP MSS size. Packets containing maximum segment sizes
exceeding this limit are handled according to the next setting.
Default: 1460 bytes
TCPMSSVPNMax
As is the case with TCPMSSMax, this is the highest Maximum Segment Size allowed. However,
this setting only controls MSS in VPN connections. This way, NetDefendOS can reduce the
effective segment size used by TCP in all VPN connections. This reduces TCP fragmentation in the
VPN connection even if hosts do not know how to perform MTU discovery.
Default: 1400 bytes
TCPMSSOnHigh
Determines the action taken on packets whose TCP MSS option exceeds the stipulated
TCPMSSMax value. Values that are too high could cause problems in poorly written TCP stacks or
give rise to large quantities of fragmented packets, which will adversely affect performance.
Default: Adjust
TCPMSSAutoClamping
Automatically clamp TCP MSS according to MTU of involved intafaces, in addition to
TCPMSSMax.
Default: Enabled
TCPMSSLogLevel
Determines when to log regarding too high TCP MSS, if not logged by TCPMSSOnHigh.
13.2. TCP Level Settings Chapter 13. Advanced Settings
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