Static PAT

DIAGRAM

      192.168.234.0/24                  10.1.5.0/24
[R2]----------+--------(fa1/0)--[R1]--(fa0/0)--------[R5]
              |              in    out
[R3]----------+
              |
[R4]----------+

CONFIG

hostname R1
!
int fa0/0
 ip nat out
!
int fa1/0
 ip nat in
!
ip nat in so sta tcp 192.168.234.2 8080 10.1.5.1 80
!
end

VERIFY

R5#telnet 10.1.5.1 80
Trying 10.1.5.1, 80 ... Open
get
HTTP/1.1 400 Bad Request
Date: Wed, 28 Dec 2016 21:04:04 GMT
Server: cisco-IOS
Accept-Ranges: none
400 Bad Request
[Connection to 10.1.5.1 closed by foreign host]
R5#

R1(config)#do sh ip nat trans
Pro Inside global      Inside local       Outside local      Outside global
tcp 10.1.5.1:80        192.168.234.2:8080 10.1.5.5:42306     10.1.5.5:42306
tcp 10.1.5.1:80        192.168.234.2:8080 ---                ---
R1(config)#

設定はinside sourceなのでoutからの戻り通信と考える。