System Tuning
From Antcor
Contents |
System Tuning Description
System Tuning NMS tab can be found under the System Tune button on System Properties NMS tab.
System Tuning consists of the following options:
- Max concurrent open connections:
This option affects the maximum number of TCP&UDP connections that can be served by the IkarusOS in total.
- TCP Timeout for established connections
This option affects the default timeout value for connections in the ESTABLISHED state.
A connection is considered to be in the ESTABLISHED state as soon as the initial 3-way handshake
has been completed and no FIN packet has been received.
- TCP Timeout for time-waiting connections
This option affects the default timeout value for connections in the TIME-WAIT state as defined by RFC 793.
As soon as a connection is closed in both directions, the server and client enters the TIME-WAIT state,
so that all stale packets have time to enter the client or server.
- TCP Timeout for finalized connections
This option defines the timeout values for both the FIN-WAIT-1 and FIN-WAIT-2 states as defined in RFC 793.
The FIN-WAIT-1 state is entered when the server send a FIN packet, while the FIN-WAIT-2 state is entered
when the server receives a FIN/ACK packet from the client in return to the initial FIN packet.
- TCP Keepalive time
This option tells the TCP/IP stack how often to send TCP keepalive packets to keep an connection
alive if it is currently unused. This value is only used when keepalive is enabled.
- Max concurrent TCP SYN requests
This option tells your box how many SYN requests to keep in memory that we have yet to get the third packet
in a 3-way handshake from. The Max concurrent TCP SYN requests option is overridden by the Send cookies to identify a valid TCP connection
option which needs to be turned on for this variable to have any effect.
- Max retransmissions of the SYN,ACK reply to a SYN request
This option tells the kernel how many times to retransmit the SYN,ACK reply to an SYN request.
In other words, this tells the system how many times to try to establish a passive TCP connection that was started by another host.
- Max retransmissions of the initial SYN packet for an active TCP connection
This option tells the kernel how many times to try to retransmit the initial SYN packet for an active TCP connection attempt.
- Send cookies to identify a valid TCP connection
This option is used to send out so called syncookies to hosts when the kernels syn backlog queue for a specific socket is overflowed.
This means that if our host is flooded with several SYN packets from different hosts, the syn backlog queue may overflow,
and hence this function starts sending out cookies to see if the SYN packets are really legit.
- ARP table "safe" number of elements
This option affects the minimum number of entries to keep in the ARP cache. The garbage collector will not run if there are
fewer than this number of entries in the cache.
- Soft limit for ARP table's elements (start deleting)
This option affects the soft maximum number of entries to keep in the ARP cache. The garbage collector will allow the number of entries to exceed this for 5 seconds before collection will be performed.
- Max elements in arp table
This option affects the hard maximum number of entries to keep in the ARP cache. The garbage collector will always run if there are more than this number of entries in the cache.
