From the outside I can port scan my pool of outside addresses and find open ports ( 25-smtp, 139-NetBios, etc). Then from the outside I can telnet to port 25 and a Microsoft mail server may respond. I traced one of these back to a Win 2000 workstation that had smtp service running.
My configuration follows. What is causing these ports to be open?
Any help is greatly appreciated!
Current configuration : 2153 bytes
no service single-slot-reload-enable
service timestamps debug datetime localtime
service timestamps log datetime localtime
no service password-encryption
logging buffered 4096 debugging
logging rate-limit console 10 except errors
enable password #####
memory-size iomem 25
clock timezone EST -5
clock summer-time EDT recurring
no ip finger
ip name-server ###.###.112.20
ip audit notify log
ip audit po max-events 100
ip address 184.108.40.206 255.255.255.0
ip nat inside
no ip address
encapsulation frame-relay IETF
service-module t1 timeslots 1-24
frame-relay lmi-type ansi
interface Serial0.1 point-to-point
ip address ##.###.144.130 255.255.255.252
ip nat outside
frame-relay interface-dlci 16
ip nat pool 1 ###.##.112.193 ###.##.112.223 netmask 255.255.255.224
I do not see any static translation for tcp port 25 for smtp from outside to inside in the config. I only see the static port (tcp and udp) 5631 and 5632 from outside mapped to 37 and 67 inside ip address. So since no static mapping for port tcp 25 for internal email server, the telnet to that port from outside should not work at all.
Try to telnet to outside ip address with port 25 and see the "show ip nat trans" on a router.
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