HP-UX IPFilter Version 15.01 Administrator's Guide

case, HP recommends that you set ip_pmtu_strategy to 3 if this value is supported on your
system, or to 0 if it is not supported. Note that for IPv4, the link-local MTU can be as low as 68
bytes. Setting ip_pmtu_strategy to 0 or 3 can significantly decrease IP throughput.
ICMP Echo Request Broadcasts (ip_respond_to_echo_broadcast)
A ping message (ICMP echo request) to a broadcast address solicits responses from multiple
systems and can generate a lot of network traffic. In security-conscious environments, HP
recommends that you disable responses to broadcast echo requests.
Default ValueValid ValuesParameter Name
10 (disable)
1 (enable)
ip_respond_to_echo_broadcast
Using ndd to Configure ICMPv4 Kernel Parameters
The ICMPv4 (ICMP) kernel tunable parameters in this chapter are all configured using the ndd
utility. Parameter values that you set by running ndd are not retained when the system reboots.
You can configure parameter values in the ndd startup file, /etc/rc.config.d/nddconf, so
ndd will set the configured values each time the system starts up. To add an ICMP configuration
value to /etc/rc.config.d/nddconf, specify ip as the transport name and use the following
syntax:
TRANSPORT_NAME[index]=ip
NDD_NAME[index]=parameter_name
NDD_VALUE[index]=value
where:
index is the index number for the entry in the nddconf file. Index numbers must start from 0
and increment sequentially.
parameter_name is the name of the ICMP parameter, such as ip_ire_gw_probe.
value is the parameter value.
For example:
TRANSPORT_NAME[0]=ip
NDD_NAME[0]=ip_ire_gw_probe
NDD_VALUE[0]=0
To configure a value for an ICMP parameters using the ndd command, specify /dev/ip as the
network device and use the following syntax:
ndd -set /dev/ip parameter_name value
For example:
ndd -set /dev/ip ip_ire_gw_probe 0
Use the following syntax to query the value of a kernel tunable:
ndd -get /dev/ip parameter_name
For example:
ndd -get /dev/ip ip_ire_gw_probe
Configuring ICMPv4 Kernel Parameters 99