Moxa IA261-I-LX [37/71] Append or delete rules

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 number.

-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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