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user72593
Asked: 2014-01-16 16:28:12 +0800 CST

Cisco ASA 5505 - NAT or Port Forward for SIP / VoIP ver 8.4

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I just had an NEC PBX installed that lets me use SIP trunks for VoIP services, My gateway is a Cisco ASA 5505 running 8.4 and I only have one public/static IP Addresses.

So far, my trunks are registering and I can make outgoing calls and everything works, but incoming calls are silent (both ways). I'm assuming its because the UDP ports 1024-1215 are not forwarded and neither is SIP (5060).

What I need to do is forward the UDP port range of 1024-1215, however it seems I can't create a port map for UDP, or define a range of ports for UDP in a static Route. Any help in the right direction would be appreciated !!! (I was told ASA 8.4 would allow forwarding of a range of ports so I upgraded and now I'm a bit lost with the new commands)

Using the ASDM I gave it a few tries but here were my results:

[OK] object network NEC_DSX
      object network NEC_DSX
[ERROR] nat (inside,outside) static interface service udp 1024-1215 1024-1215 

nat (inside,outside) static interface service udp 1024-1215 1024-1215 
                                                      ^
ERROR: % Invalid input detected at '^' marker.


I also tried:

[OK] object network NEC_DSX
      object network NEC_DSX
[ERROR] nat (inside,outside) static interface service udp 1024 1024 
     NAT unable to reserve ports.

------------------------
Here is my current config :

ASA Version 8.4(4) 
!
hostname ciscoasa
enable password 8Ry2YjIyt7RRXU24 encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
names
name 24.173.xxx.xxx StaticOutside description WAN IP
!
interface Ethernet0/0
 switchport access vlan 2
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Ethernet0/4
!
interface Ethernet0/5
!
interface Ethernet0/6
!
interface Ethernet0/7
!
interface Vlan1
 nameif inside
 security-level 100
 ip address 192.168.3.1 255.255.255.0 
!
interface Vlan2
 nameif outside
 security-level 0
 ip address StaticOutside 255.255.255.252 
!
boot system disk0:/asa844-k8.bin
boot system disk0:/asa832-k8.bin
ftp mode passive
object network obj-192.168.3.5
 host 192.168.3.5
object network obj_any
 subnet 0.0.0.0 0.0.0.0
object network NEC_DSX
 host 192.168.3.150
 description NEC DSX SYSTEM
access-list outside_access_in extended permit tcp any host 192.168.3.5 eq 3389 log disable 
pager lines 24
logging asdm informational
mtu inside 1500
mtu outside 1500
icmp unreachable rate-limit 1 burst-size 1
asdm image disk0:/asdm-649-103.bin
no asdm history enable
arp timeout 14400
!
object network obj-192.168.3.5
 nat (inside,outside) static interface service tcp 3389 3389 
object network obj_any
 nat (inside,outside) dynamic interface
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 24.173.100.85 1
timeout xlate 3:00:00
timeout pat-xlate 0:00:30
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00
timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00
timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute
timeout tcp-proxy-reassembly 0:01:00
timeout floating-conn 0:00:00
dynamic-access-policy-record DfltAccessPolicy
user-identity default-domain LOCAL
http server enable
http 192.168.3.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
telnet timeout 5
ssh timeout 5
ssh key-exchange group dh-group1-sha1
console timeout 0

dhcpd auto_config outside
!
dhcpd address 192.168.3.10-192.168.3.38 inside
dhcpd dns 4.2.2.1 4.2.2.2 interface inside
dhcpd enable inside
!
threat-detection basic-threat
threat-detection statistics host
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
webvpn
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
 parameters
  message-length maximum client auto
  message-length maximum 512
policy-map global_policy
 class inspection_default
  inspect dns preset_dns_map 
  inspect ftp 
  inspect h323 h225 
  inspect h323 ras 
  inspect rsh 
  inspect rtsp 
  inspect esmtp 
  inspect sqlnet 
  inspect skinny  
  inspect sunrpc 
  inspect xdmcp 
  inspect sip  
  inspect netbios 
  inspect tftp 
  inspect ip-options 
 class class-default
  user-statistics accounting
!
service-policy global_policy global
prompt hostname context 
no call-home reporting anonymous
Cryptochecksum:85d3bff9e7eb561bf8ee4f27b11a6cf4
: end
cisco

1 Answers

  1. Best Answer

    You don't have to explicitly forward RTP ports (>1024) as you have sip inspect turned on. When a SIP INVITE comes through, the router will open the appropriate RTP ports for the duration of the call.

    As far as NATing SIP, you are missing the NAT command, and the access-list entry:

    ! this should be tightened to allow traffic only from your telephone company, or 
! people with bad intent will happily place international calls on your account
access-list outside_access_in extended permit udp any host 192.168.3.150 eq 5060 
! nat 5060 to 5060
object network NEC_DSX
 nat (inside,outside) static interface service udp 5060 5060

    Though it is not needed, the proper syntax to forward a range is:

    object service rtp-1024-1215 
 service udp source range 1024 1215
object network NEC_DSX_RTP
 host 192.168.3.150
 nat (inside,outside) static interface service rtp-1024-1215 rtp-1024-1215
    • 1