linux-imx

/proc/sys/net/ipv4/* Variables:

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ip_forward - BOOLEAN

    0 - disabled (default)

    not 0 - enabled

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    Forward Packets between interfaces.

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    This variable is special, its change resets all configuration

    parameters to their default state (RFC1122 for hosts, RFC1812

    for routers)

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ip_default_ttl - INTEGER

    Default value of TTL field (Time To Live) for outgoing (but not

    forwarded) IP packets. Should be between 1 and 255 inclusive.

    Default: 64 (as recommended by RFC1700)

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ip_no_pmtu_disc - INTEGER

    Disable Path MTU Discovery. If enabled in mode 1 and a

    fragmentation-required ICMP is received, the PMTU to this

    destination will be set to min_pmtu (see below). You will need

    to raise min_pmtu to the smallest interface MTU on your system

    manually if you want to avoid locally generated fragments.

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    In mode 2 incoming Path MTU Discovery messages will be

    discarded. Outgoing frames are handled the same as in mode 1,

    implicitly setting IP_PMTUDISC_DONT on every created socket.

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    Mode 3 is a hardened pmtu discover mode. The kernel will only

    accept fragmentation-needed errors if the underlying protocol

    can verify them besides a plain socket lookup. Current

    protocols for which pmtu events will be honored are TCP, SCTP

    and DCCP as they verify e.g. the sequence number or the

    association. This mode should not be enabled globally but is

    only intended to secure e.g. name servers in namespaces where

    TCP path mtu must still work but path MTU information of other

    protocols should be discarded. If enabled globally this mode

    could break other protocols.

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    Possible values: 0-3

    Default: FALSE

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min_pmtu - INTEGER

    default 552 - minimum discovered Path MTU

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ip_forward_use_pmtu - BOOLEAN

    By default we don't trust protocol path MTUs while forwarding

    because they could be easily forged and can lead to unwanted

    fragmentation by the router.

    You only need to enable this if you have user-space software

    which tries to discover path mtus by itself and depends on the

    kernel honoring this information. This is normally not the

    case.

    Default: 0 (disabled)

    Possible values:

    0 - disabled

    1 - enabled

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fwmark_reflect - BOOLEAN

    Controls the fwmark of kernel-generated IPv4 reply packets that are not

    associated with a socket for example, TCP RSTs or ICMP echo replies).

    If unset, these packets have a fwmark of zero. If set, they have the

    fwmark of the packet they are replying to.