User`s manual

IA260-261-262 EM-2260 LX User’s Manual Managing Communications
Examples:
# iptables -L -n
In this example, since we do not use the -t parameter, the system uses the default ‘filter’ table.
Three chains are included: INPUT, OUTPUT, and FORWARD. INPUT chains are accepted
automatically, and all connections are accepted without being filtered.
#iptables –F
#iptables –X
#iptables -Z
Define policy for chain rules
Usage:
# iptables [-t tables] [-P] [INPUT, OUTPUT, FORWARD, PREROUTING, OUTPUT, POSTROUTING]
[ACCEPT, DROP]
-P: Set the policy for the chain to the given target.
INPUT: For packets coming into the IA260/IA261/IA262/EM-2260.
OUTPUT: For locally-generated packets.
FORWARD: For packets routed out through the IA260/IA261/IA262/EM-2260.
PREROUTING: To alter packets as soon as they come in.
POSTROUTING: To alter packets as they are about to be sent out.
Examples:
#iptables –P INPUT DROP
#iptables –P OUTPUT ACCEPT
#iptables –P FORWARD ACCEPT
#iptables –t nat –P PREROUTING ACCEPT
#iptables –t nat –P OUTPUT ACCEPT
#iptables -t nat –P POSTROUTING ACCEPT
In this example, the policy accepts outgoing packets and denies incoming packets.
Append or delete rules:
Usage:
# iptables [-t table] [-AI] [INPUT, OUTPUT, FORWARD] [-io interface] [-p tcp, udp, icmp,
all] [-s IP/network] [--sport ports] [-d IP/network] [--dport ports] –j [ACCEPT. DROP]
-A: Append one or more rules to the end of the selected chain.
-I: Insert one or more rules in the selected chain as the given rule number.
-i: Name of an interface via which a packet is going to be received.
-o: Name of an interface via which a packet is going to be sent.
-p: The protocol of the rule or of the packet to check.
-s: Source address (network name, host name, network IP address, or plain IP address).
--sport: Source port number.
-d: Destination address.
--dport: Destination port nu mber.
-j: Jump target. Specifies the target of the rules; i.e., how to handle matched packets. For
example, ACCEPT the packet, DROP the packet, or LOG the packet.
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