Equivalent TCP parameters in Solaris and HP-UX

[Guilherme Belinelo]

Hi,

I need to change some TCP parameters in HP-UX as recommended by my application developer. The problem is that I just have the Solaris parameters. Does anybody know the names or equivalence for the Solaris parameters below ?

tcp_conn_req_max_q0
tcp_conn_req_max_q
tcp_close_wait_interval
tcp_fin_wait_2_flush_interval

[James A. Donovan]

The parameters tcp_conn_req_max_q0, tcp_conn_req_max_q were introduced with Solaris 2.6, the equivalent parameter in HP-UX is tcp_conn_request_max.

The equivalent to tcp_close_wait_interval (changes to tcp_time_wait_interval in Solaris 7) under HP-UX is called tcp_time_wait_interval.

Finally, the HP-UX equivalent for tcp_fin_wait_2_flush_interval is tcp_fin_wait_2_timeout.

BTW, an excellent TCP tuning guide (based on Solaris, but I think is generally relevant) can be found at http://www.rvs.uni-hannover.de/people/voeckler/tune/EN/tune.html

[Guilherme Belinelo]

Jim,

Thanks for the site, it seems very usefull.

I?ve just found out a parameter on HP-UX called tcp_syn_rcvd_max that is related to max number of connections in SYN_RCVD state. May I use it instead of tcp_conn_req_max for the tcp_conn_req_max_q0 in Solaris ?

[James A. Donovan · Accepted solution]

Yes, it is basically the equivalent. I would follow the advice of the paper I mentioned above, and make sure that this value is larger than the value you give to tcp_conn_request_max.

# ndd -h tcp_syn_rcvd_max

tcp_syn_rcvd_max:

Controls the SYN attack defense of TCP. The value specifies
the maximum number of suspect connections that will be allowed
to persist in SYN_RCVD state. For SYN attack defense to work,
this number must be large enough so that a legitimate connection
will not age out of the list before an ACK is received from the
remote host. This number is a function of the speed at which
bogus SYNs are being received and the maximum round trip time
for a valid remote host. This is very difficult to estimate
dynamically, but the default value of 500 has proven to be highly
effective. [1,10000] Default: 500 connections