1

Hello see below network diagram.

Network Diagram

I am trying to configure the Branch Router (10.1.1.1) to use TACACS AAA on the HQ-AAA-Server host (192.168.10.10). TACACS works fine for the Branch-FW1 ASA device over the VPN tunnel to HQ-FW1.

I can see traffic on wireshark indicating that when I try to log on to the Branch Router TCP SYN packets are sent on port 49 but no replies are recieved and I see no VPN traffic generated so it looks like the BR-FW1 ASA is blocking the requests.

I have an ACL in Branch-FW1 to allow TACACS traffic from the outside interface and another to mark it as interesting traffic for the VPN tunnel:

VPN Tunnel ACL:

access-list HQFTPACL permit ip object net-local object net-remote
access-list HQFTPACL permit tcp host 10.1.1.1 host 192.168.10.10 eq tacacs

Outside ACL:

access-list OUTSIDE-ACL extended permit tcp host 10.1.1.1 host 192.168.10.10 eq tacacs
access-group OUTSIDE-ACL in interface outside

Using packet tracer it looks as if an implicit deny on an ACL is blocking TACACS traffic coming from the outside but I cannot work out why this would be?

Branch-FW(config)# packet-tracer input outside tcp 10.1.1.1 1234 192.168.10.10$

Phase: 1
Type: ROUTE-LOOKUP
Subtype: Resolve Egress Interface
Result: ALLOW
Config:
Additional Information:
found next-hop 10.1.1.1 using egress ifc  outside

Phase: 2
Type: ACCESS-LIST
Subtype:
Result: DROP
Config:
Implicit Rule
Additional Information:

Result:
output-interface: outside
output-status: up
output-line-status: up
Action: drop

Full Branch-FW1 config:


: 
: Serial Number: 9A2EL3EHE12
: Hardware:   ASAv, 2048 MB RAM, CPU Pentium II 2000 MHz
: Written by admin at 13:15:20.359 UTC Fri Dec 10 2021
!
ASA Version 9.5(2)204 
!
hostname Branch-FW
domain-name asecuritycompany.com
enable password 8Ry2YjIyt7RRXU24 encrypted
xlate per-session deny tcp any4 any4
xlate per-session deny tcp any4 any6
xlate per-session deny tcp any6 any4
xlate per-session deny tcp any6 any6
xlate per-session deny udp any4 any4 eq domain
xlate per-session deny udp any4 any6 eq domain
xlate per-session deny udp any6 any4 eq domain
xlate per-session deny udp any6 any6 eq domain
names
!
interface GigabitEthernet0/0
 description TO THE BRANCH ROUTER OUTSIDE 10.1.1.0/30 NETWORK
 nameif outside
 security-level 0
 ip address 10.1.1.2 255.255.255.252 
!
interface GigabitEthernet0/1
 description TO THE BRANCH INSIDE 10.1.10.0/24 NETWORK
 nameif inside
 security-level 100
 ip address 10.1.10.1 255.255.255.0 
!
interface GigabitEthernet0/2
 shutdown
 no nameif
 no security-level
 no ip address
!
interface GigabitEthernet0/3
 shutdown
 no nameif
 no security-level
 no ip address
!
interface GigabitEthernet0/4
 shutdown
 no nameif
 no security-level
 no ip address
!
interface GigabitEthernet0/5
 shutdown
 no nameif
 no security-level
 no ip address
!
interface GigabitEthernet0/6
 shutdown
 no nameif
 no security-level
 no ip address
!
interface Management0/0
 shutdown
 no nameif
 no security-level
 no ip address
!
banner login ****************************************************************
banner login *                                                              *
banner login *     UNAUTHORIZED ACCESS TO THIS DEVICE IS PROHIBITED         *
banner login *                                                              *
banner login *   You must have explicit, authorized permission to access    *
banner login *   or configure this device.                                  *
banner login *                                                              *
banner login *   Unauthorized attempts and actions to access or use this    *
banner login *   system may result in civil and/or criminal penalties.      *
banner login *                                                              *
banner login *   All activities performed on this device are logged         *
banner login *   and monitored.                                             *
banner login *                                                              *
banner login ****************************************************************
ftp mode passive
dns server-group DefaultDNS
 domain-name asecuritycompany.com
object network net-local
 subnet 10.1.10.0 255.255.255.0
object network net-outside
 subnet 10.1.1.0 255.255.255.252
object network net-remote
 subnet 192.168.10.0 255.255.255.0
access-list HQFTPACL extended permit ip object net-local object net-remote 
access-list HQFTPACL extended permit tcp host 10.1.1.1 host 192.168.10.10 eq tacacs 
access-list OUTSIDE-ACL extended permit tcp host 10.1.1.1 host 192.168.10.10 eq tacacs 
pager lines 23
mtu outside 1500
mtu inside 1500
no failover
no monitor-interface service-module 
icmp unreachable rate-limit 1 burst-size 1
no asdm history enable
arp timeout 14400
no arp permit-nonconnected
nat (inside,outside) source static net-local net-local destination static net-remote net-remote
!
object network net-local
 nat (inside,outside) dynamic interface
object network net-outside
 nat (inside,outside) dynamic interface
access-group OUTSIDE-ACL in interface outside
route outside 0.0.0.0 0.0.0.0 10.1.1.1 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 sctp 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
aaa-server HQ-TACACS-GROUP protocol tacacs+
aaa-server HQ-TACACS-GROUP (inside) host 192.168.10.10
 key testing123
user-identity default-domain LOCAL
aaa authentication serial console HQ-TACACS-GROUP LOCAL
aaa authentication telnet console HQ-TACACS-GROUP LOCAL
aaa authentication ssh console HQ-TACACS-GROUP LOCAL
aaa authentication enable console HQ-TACACS-GROUP LOCAL
aaa authorization command HQ-TACACS-GROUP LOCAL
aaa accounting ssh console HQ-TACACS-GROUP
aaa accounting enable console HQ-TACACS-GROUP
aaa accounting command HQ-TACACS-GROUP
aaa accounting serial console HQ-TACACS-GROUP
aaa accounting telnet console HQ-TACACS-GROUP
no snmp-server location
no snmp-server contact
crypto ipsec ikev1 transform-set HQFTPTRANS esp-aes-256 esp-sha-hmac 
crypto ipsec security-association pmtu-aging infinite
crypto map HQFTPMAP 1 match address HQFTPACL
crypto map HQFTPMAP 1 set pfs group1
crypto map HQFTPMAP 1 set peer 192.168.20.2 
crypto map HQFTPMAP 1 set ikev1 transform-set HQFTPTRANS
crypto map HQFTPMAP interface outside
crypto ca trustpoint _SmartCallHome_ServerCA
 no validation-usage
 crl configure
crypto ca trustpool policy
 auto-import
crypto ikev1 enable outside
crypto ikev1 policy 10
 authentication pre-share
 encryption aes-256
 hash sha
 group 2
 lifetime 86400
telnet timeout 5
ssh stricthostkeycheck
ssh 192.168.10.21 255.255.255.255 outside
ssh 192.168.10.2 255.255.255.255 outside
ssh 192.168.20.2 255.255.255.255 outside
ssh 10.1.10.1 255.255.255.255 outside
ssh 10.1.10.3 255.255.255.255 outside
ssh 192.168.10.21 255.255.255.255 inside
ssh 192.168.10.2 255.255.255.255 inside
ssh 192.168.20.2 255.255.255.255 inside
ssh 10.1.10.1 255.255.255.255 inside
ssh 10.1.10.3 255.255.255.255 inside
ssh timeout 10
ssh version 2
ssh key-exchange group dh-group14-sha1
console timeout 0
management-access inside
threat-detection basic-threat
threat-detection statistics access-list
no threat-detection statistics tcp-intercept
dynamic-access-policy-record DfltAccessPolicy
username localadmin password zDkbp36jt66L0Z6u encrypted privilege 15
tunnel-group 192.168.20.2 type ipsec-l2l
tunnel-group 192.168.20.2 ipsec-attributes
 ikev1 pre-shared-key SECRET-KEY
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map type inspect dns migrated_dns_map_1
 parameters
  message-length maximum client auto
  message-length maximum 512
policy-map global_policy
 class inspection_default
  inspect dns migrated_dns_map_1 
  inspect ftp 
  inspect h323 h225 
  inspect h323 ras 
  inspect ip-options 
  inspect netbios 
  inspect rsh 
  inspect rtsp 
  inspect skinny  
  inspect esmtp 
  inspect sqlnet 
  inspect sunrpc 
  inspect tftp 
  inspect sip  
  inspect xdmcp 
  inspect icmp 
!
service-policy global_policy global
prompt hostname context 
no call-home reporting anonymous
call-home
 profile CiscoTAC-1
  no active
  destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
  destination address email callhome@cisco.com
  destination transport-method http
  subscribe-to-alert-group diagnostic
  subscribe-to-alert-group environment
  subscribe-to-alert-group inventory periodic monthly
  subscribe-to-alert-group configuration periodic monthly
  subscribe-to-alert-group telemetry periodic daily
 profile License
  destination address http https://tools.cisco.com/its/service/oddce/services/DDCEService
  destination transport-method http
Cryptochecksum:5c75c343565aaa10bcf4a87ecc2111bf
: end
1
  • 1
    Like I said before, you can’t use packet-tracer for inbound tunnel traffic, only for outbound. You would have to run packet-tracer on both sides of the tunnel to verify that outbound is allowed and hitting the right rules and NAT (NAT exemption) statements. As for the main issue, I’m still at a loss for why it’s not working unless there’s a host issue. The firewalls look fine.
    – Jesse P.
    Dec 10, 2021 at 14:52

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