Microsens MS453490M Management Guide User Manual
Page 671
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| General Security Measures
IP Source Guard
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Interface Configuration (Ethernet)
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Source guard is used to filter traffic on an insecure port which receives
messages from outside the network or fire wall, and therefore may be
subject to traffic attacks caused by a host trying to use the IP address
of a neighbor.
◆
Setting source guard mode to “sip” or “sip-mac” enables this function
on the selected port. Use the “sip” option to check the VLAN ID, source
IP address, and port number against all entries in the binding table.
Use the “sip-mac” option to check these same parameters, plus the
source MAC address. Use the no ip source guard command to disable
this function on the selected port.
◆
When enabled, traffic is filtered based upon dynamic entries learned via
DHCP snooping, or static addresses configured in the source guard
binding table.
◆
Table entries include a MAC address, IP address, lease time, entry type
(Static-IP-SG-Binding, Dynamic-DHCP-Binding, VLAN identifier, and
port identifier.
◆
Static addresses entered in the source guard binding table with the
command (
) are automatically
configured with an infinite lease time. Dynamic entries learned via
DHCP snooping are configured by the DHCP server itself.
◆
If the IP source guard is enabled, an inbound packet’s IP address (sip
option) or both its IP address and corresponding MAC address (sip-mac
option) will be checked against the binding table. If no matching entry
is found, the packet will be dropped.
◆
Filtering rules are implemented as follows:
■
If DHCP snooping is disabled (see
), IP source guard will
check the VLAN ID, source IP address, port number, and source
MAC address (for the sip-mac option). If a matching entry is found
in the binding table and the entry type is static IP source guard
binding, the packet will be forwarded.
■
If the DHCP snooping is enabled, IP source guard will check the
VLAN ID, source IP address, port number, and source MAC address
(for the sip-mac option). If a matching entry is found in the binding
table and the entry type is static IP source guard binding, or
dynamic DHCP snooping binding, the packet will be forwarded.
■
If IP source guard if enabled on an interface for which IP source
bindings (dynamically learned via DHCP snooping or manually
configured) are not yet configured, the switch will drop all IP traffic
on that port, except for DHCP packets.
■
Only unicast addresses are accepted for static bindings.