ip_respond_to_echo_broadcast and ip6_respond_to_echo_multicast
| Description | Control whether IPv4
or IPv6 responds to broadcast ICMPv4 echo request or multicast ICMPv6 echo
request.
|
| Default | 1 (enabled)
|
| Range | 0 (disabled), 1 (enabled)
|
| Dynamic? | Yes
|
| When to Change | If you do not want
this behavior for security reasons, disable it.
|
| Commitment Level | Unstable
|
ip_send_redirects and ip6_send_redirects
| Description | Control whether IPv4
or IPv6 sends out ICMPv4 or ICMPv6 redirect messages. See also "ip_forwarding and ip6_forwarding".
|
| Default | 1 (enabled)
|
| Range | 0 (disabled), 1 (enabled)
|
| Dynamic? | Yes
|
| When to Change | If you do not want
this behavior for security reasons, disable it.
|
| Commitment Level | Unstable
|
ip_forward_src_routed and ip6_forward_src_routed
| Description | Control whether IPv4
or IPv6 forwards packets with source IPv4 routing options or IPv6 routing
headers. See also "ip_forwarding and ip6_forwarding".
|
| Default | 1 (enabled)
|
| Range | 0 (disabled), 1 (enabled)
|
| Dynamic? | Yes
|
| When to Change | If you do not want
this behavior for security reasons, disable it.
|
| Commitment Level | Unstable
|
ip_addrs_per_if
| Description | The maximum number of
logical interfaces associated with a real interface.
|
| Default | 256
|
| Range | 1 to 8192
|
| Dynamic? | Yes
|
| When to Change | Do not change the
value. If more logical interfaces are required, increase the value, but recognize
that this change might have a negative impact on IP's performance.
|
| Commitment Level | Unstable
|
ip_strict_dst_multihoming and ip6_strict_dst_multihoming
| Description | Determine whether a
packet arriving on a non-forwarding interface can be accepted for an IP address
that is not explicitly configured on that interface. If ip_forwarding is enabled, or xxx:ip_forwarding for the appropriate interfaces is enabled, then this parameter
is ignored, because the packet is actually forwarded.
Refer to RFC 1122 3.3.2.4.
|
| Default | 0 (loose multihoming)
|
| Range | 0 = Off (loose multihoming)
1 = On (strict multihoming)
|
| Dynamic? | Yes
|
| When to Change | If a machine has
interfaces that cross strict networking domains (for example, a firewall or
a VPN node), set this variable to 1.
|
| Commitment Level | Unstable
|
IP Tunable Parameters With Additional Cautions
Changing the following parameters is not recommended unless there are
extenuating circumstances that are described with each parameter.
ip_ire_pathmtu_interval
| Description | The interval in milliseconds
when IP flushes the path maximum transfer unit (PMTU) discovery information,
and tries to rediscover PMTU.
Refer to RFC 1191 on PMTU discovery.
|
| Default | 10 minutes
|
| Range | 5 seconds to 277 hours
|
| Dynamic? | Yes
|
| When to Change | Do not change this
value.
|
| Commitment Level | Unstable
|
ip_icmp_return_data_bytes and ip6_icmp_return_data_bytes
| Description | When IPv4 or IPv6 sends
an ICMPv4 or ICMPv6 error message, it includes the IP header of the packet
that causes the error message. This parameter controls how many extra bytes
of the packet beyond the IPv4 or IPv6 header to be included in the ICMPv4
or ICMPv6 error message.
|
| Default | 64 bytes
|
| Range | 8 to 65,536 bytes
|
| Dynamic? | Yes
|
| When to Change | Do not change the
value. Including more information in an ICMP error message might help in diagnosing
network problems. If this feature is needed, increase the value.
|
| Commitment Level | Unstable
|
TCP Tunable Parameters
tcp_deferred_ack_interval
| Description | The time-out value for
TCP delayed acknowledgment (ACK) timer in milliseconds for hosts that are
not directly connected.
Refer to RFC 1122, 4.2.3.2.
|
| Default | 100 milliseconds
|
| Range | 1 millisecond to 1 minute
|
| Dynamic? | Yes
|
| When to Change | Do not increase this
value to more than 500 milliseconds.
If in some circumstances, slow network links (less than 57.6 Kbps) with
greater than 512 bytes maximum segment size (MSS) when the interval is short
for receiving more than one TCP segment, increase the value.
|
| Commitment Level | Unstable
|
