Linux iptables: Port Redirection Example 端口重定向

How do I redirect 80 port to 8123 using iptables?

使用iptables将80端口重定向到8123端口

You can easily redirect incoming traffic by inserting rules into PREROUTING chain of the nat table. You can set destination port using the REDIRECT target.

你可以通过在nat表的PREROUTING链插入规则来实现端口重定向，可以通过REDIRECT 来设置目的端口

Syntax

The syntax is as follows to redirect tcp $srcPortNumber port to $dstPortNumber:

下面的语法为将tcp端口$srcPortNumber 重定向到 $dstPortNumber

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport $srcPortNumber -j REDIRECT --to-port $dstPortNumbe

The syntax is as follows to redirect udp $srcPortNumber port to $dstPortNumber:

下面的语法为将udp端口$srcPortNumber 重定向到 $dstPortNumber

iptables -t nat -A PREROUTING -i eth0 -p udp --dport $srcPortNumber -j REDIRECT --to-port $dstPortNumbe

Replace eth0 with your actual interface name. The following syntax match for source and destination ips:

iptables -t nat -I PREROUTING --src $SRC_IP_MASK --dst $DST_IP -p tcp --dport $portNumber -j REDIRECT --to-ports $rediectPort Examples:

The following example redirects TCP port 25 to port 2525:

下面的例子讲tcp端口25重定向到2525

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 25 -j REDIRECT --to-port 2525

In this example all incoming traffic on port 80 redirect to port 8123

iptables -t nat -I PREROUTING --src 0/0 --dst 192.168.1.5 -p tcp --dport 80 -j REDIRECT --to-ports 8123

Quoting from the iptables man page:

This target is only valid in the nat table, in the PREROUTING and OUTPUT chains, and user-defined chains which are only called from those chains. It redirects the packet to the machine itself by changing the destination IP to the primary address of the incoming interface (locally-generated packets are mapped to the 127.0.0.1 address). It takes one option: --to-ports port[-port] This specifies a destination port or range of ports to use: without this, the destination port is never altered. This is only valid if the rule also specifies -p tcp or -p udp.

The OUTPUT chain example:

iptables -t nat -I OUTPUT --src 0/0 --dst 192.168.1.5 -p tcp --dport 80 -j REDIRECT --to-ports 8123 How Do I View NAT Rules?

Type the following command:

iptables -t nat -L -n -v How Do I Save NAT Redirect Rules?

Type the following command:

iptables-save References:

• man page - iptables

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