方法一：

A. 在object下做nat

object network test
 host 100.1.1.3
object network R3
 host 192.168.2.1

object network R3
 nat (inside,outside) static test service tcp telnet 50000

###############################################################

外网test port 50000映射到内网 R3 port 23（telnet）。

###############################################################

ciscoasa(config)# show xlate
1 in use, 3 most used
Flags: D - DNS, i - dynamic, r - portmap, s - static, I - identity, T - twice
TCP PAT from inside:192.168.2.1 23-23 to outside:100.1.1.3 50000-50000
    flags sr idle 0:00:06 timeout 0:00:00

###############################################################

B.

object network server
 subnet 192.168.2.1 255.255.255.255
object service telnet
 service tcp source eq telnet
object network test
 host 100.1.1.3
object service 50000
 service tcp source eq 50000

nat (inside,outside) source static server test service telnet 50000

###############################################################

此处的 telnet为object的名称。

###############################################################

ciscoasa(config)# show xlate
1 in use, 3 most used
Flags: D - DNS, i - dynamic, r - portmap, s - static, I - identity, T - twice
TCP PAT from inside:192.168.2.1 23-23 to outside:100.1.1.3 50000-50000
    flags sr idle 0:03:11 timeout 0:00:00
ciscoasa(config)#

###############################################################

端口23已经成功映射50000。

###############################################################

方法二：范围映射。多个不连续端口映射，使用如下方法。

object network test
 host 100.1.1.3
object network R3
 host 192.168.2.1

object service telnet
 service tcp source eq telnet
object service smtp
 service tcp source eq smtp

object service 3000-5000
 service tcp source range 3000 5000

nat (inside,outside) source static R3 test service telnet telnet
nat (inside,outside) source static R3 test service smtp smtp

nat (inside,outside) source static R3 test service 3000-5000 3000-5000

ciscoasa(config)# show xlate
3 in use, 9 most used
Flags: D - DNS, i - dynamic, r - portmap, s - static, I - identity, T - twice
TCP PAT from inside:192.168.2.1 23-23 to outside:100.1.1.3 23-23
    flags sr idle 0:16:33 timeout 0:00:00
TCP PAT from inside:192.168.2.1 25-25 to outside:100.1.1.3 25-25
    flags sr idle 0:16:02 timeout 0:00:00
TCP PAT from inside:192.168.2.1 3000-5000 to outside:100.1.1.3 3000-5000
    flags sr idle 0:01:58 timeout 0:00:00
ciscoasa(config)#