Access list, SOURCE NAT and DEST NAT
U
SER
G
UIDE
164
LABEL
is a symbolic name that identify the l'access-list
NUM
is the order number of the access-list and it tells the order of evaluation
ACTION
tells the action to execute and it can be:
o
deny
o
deny-log
o
permit
o
permit-log
PROTOCOL
tells which protocol is to be used, and it can be:
o
TCP
o
UDP
o
ICMP
o
GRE
o
OSPF
o
L2TPV3
o
ANY
ADDRESS
can be a network prefix (
10.10.10.0/24
) or the keyword
any
(to point any
address) or the keyword
this
(to point any address of the router itself)
PORT
is a numeric value that identify the UDP or TCP port, or a string that identify the
service (Telnet, SSH, SNMP,...) or the keyword
any
.
When defined, through the command:
set apply-acl LABEL in-interface INTF out-interface INTF
you specify the network interfaces to which the access-list have to be applied.
For example, suppose to have a router where
atm0
is the interface to the public network and
eth0
to the internal one, to allow the TCP traffic from the external subnet
10.10.0.0/16
towards the
internal subnet
192.168.1.0
and block everything else:
set access-list secacc 10 permit protocol tcp from 10.10.0.0/16 to 192.168.1.0/24
set access-list secacc 20 deny protocol tcp from any to any
set apply-acl secacc in-interface atm0 out-interface eth0
To allow the host
88.1.1.1
to
access the router only to through Telnet:
set access-list telnet 10 permit protocol tcp from 10.10.0.0/16 source-port any to 192.168.1.0/24
set access-list secacc 20 deny protocol tcp from any to any
set apply-acl secacc in-interface atm0 out-interface eth0
To remove a certain
access-list
:
set no-access-list LABEL NUM
to remove all the
access-lists
related to a
LABEL
:
set no-access-list LABEL
S
OURCE
NAT
The command