이러한 모든 증상이 나타납니다.
Cisco FTD(Firewall Threat Defense) 디바이스에서 직접 시작되는 Traceroute 명령은 외부 IP 주소를 대상으로 지정할 때 모든 홉에 대해 일관되게 "* * * *"만 반환합니다
동일한 대상에 대한 ICMP ping에 성공했으며 액세스 제어 정책에서 ICMP가 명시적으로 허용됩니다.
이러한 동작으로 인해 FTD 디바이스에서 시작되는 트래픽에 대한 경로 홉에 대한 가시성이 차단되어 네트워크 경로 트러블슈팅 작업에 영향을 줍니다.
예
대상에 대한 Ping이 작동 중입니다.
firepower# ping 192.168.203.89 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.203.89, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/10 ms
그러나 traceroute는
firepower# traceroute 192.168.203.89 Type escape sequence to abort. Tracing the route to 192.168.203.89 1* * * 2* * * 3* * * ... 30* * * firepower#
가능한 솔루션은 구성된 NAT 규칙의 목적에 따라 다릅니다.
아웃바운드 액세스에 대해서만 내부 서버 IP를 변환하는 것이 목표인 경우 NAT 규칙을 단방향으로 구성할 수 있습니다.
FMC에서는 NAT 규칙 Advanced 옵션에서 이 작업을 수행할 수 있습니다.
구축된 NAT 컨피그레이션:
firepower# show run nat nat (INSIDE,OUTSIDE) source static server_host interface unidirectional firepower#
firepower# traceroute 192.168.203.89 Type escape sequence to abort. Tracing the route to 192.168.203.89 1 192.168.201.88 2 msec 2 msec 2 msec 2 192.168.203.89 1 msec * 1 msec
외부에서 내부 서버에 연결할 수 있는 것이 목표인 경우 포트 전달을 구성하여 NAT 규칙을 더 구체적으로 지정할 수 있습니다.
구축된 NAT 컨피그레이션:
firepower# show run nat nat (INSIDE,OUTSIDE) source static server_host interface service SVC_25769850586 SVC_25769850587
firepower# traceroute 192.168.203.89 Type escape sequence to abort. Tracing the route to 192.168.203.89 1 192.168.201.88 2 msec 2 msec 2 msec 2 192.168.203.89 1 msec * 1 msec
이는 Wireshark에서 확인할 수 있습니다.
방화벽이 인그레스 패킷을 처리하는 방법을 보려면 추적을 사용하여 방화벽 이그레스 인터페이스의 패킷 캡처를 활성화합니다.
firepower# capture CAPI trace interface OUTSIDE match ip host 192.168.203.89 host 192.168.201.100
ping을 사용하여 테스트:
firepower# ping 192.168.203.89 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.203.89, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
그런 다음 traceroute로 테스트합니다.
firepower# traceroute 192.168.203.89 Type escape sequence to abort. Tracing the route to 192.168.203.89 1* * * 2* * * 3* * * 4* * * 5* * * 6* * * 7* * * …
캡처 내용을 확인합니다.
firepower# show capture CAPI 190 packets captured 1: 13:50:27.345471 802.1Q vlan#201 P0 192.168.201.200 > 192.168.203.89 icmp: echo request 2: 13:50:27.345975 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply 3: 13:50:27.346219 802.1Q vlan#201 P0 192.168.201.200 > 192.168.203.89 icmp: echo request 4: 13:50:27.346600 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply 5: 13:50:27.346814 802.1Q vlan#201 P0 192.168.201.200 > 192.168.203.89 icmp: echo request 6: 13:50:27.347165 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply 7: 13:50:27.347378 802.1Q vlan#201 P0 192.168.201.200 > 192.168.203.89 icmp: echo request 8: 13:50:27.347714 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply 9: 13:50:27.347928 802.1Q vlan#201 P0 192.168.201.200 > 192.168.203.89 icmp: echo request 10: 13:50:27.348279 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply 11: 13:50:33.229724 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33434: udp 0 12: 13:50:33.232562 802.1Q vlan#201 P0 192.168.201.88 > 192.168.201.200 icmp: time exceeded in-transit 13: 13:50:36.220279 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33435: udp 0 14: 13:50:36.222827 802.1Q vlan#201 P0 192.168.201.88 > 192.168.201.200 icmp: time exceeded in-transit 15: 13:50:39.220172 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33436: udp 0 16: 13:50:39.222675 802.1Q vlan#201 P0 192.168.201.88 > 192.168.201.200 icmp: time exceeded in-transit 17: 13:50:42.220157 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33437: udp 0 18: 13:50:42.220737 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33437 unreachable 19: 13:50:45.220264 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33438: udp 0 20: 13:50:45.220752 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33438 unreachable 21: 13:50:48.220157 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33439: udp 0 22: 13:50:48.220645 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33439 unreachable 23: 13:50:51.220157 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33440: udp 0 24: 13:50:51.220645 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33440 unreachable 25: 13:50:54.220264 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33441: udp 0 26: 13:50:54.220752 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33441 unreachable 27: 13:50:57.220157 802.1Q vlan#201 P0 192.168.201.200.49168 > 192.168.203.89.33442: udp 0 28: 13:50:57.220645 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: 192.168.203.89 udp port 33442 unreachable
ping 테스트에서 인그레스 ICMP 패킷을 추적합니다.
패킷 #2는 패킷 모드에서 보낸 ICMP ping 요청에 대한 #1.
firepower# show capture CAPI packet-number 2 trace 190 packets captured 2: 13:50:27.345975 802.1Q vlan#201 P0 192.168.203.89 > 192.168.201.200 icmp: echo reply … Phase: 4 Type: FLOW-LOOKUP Subtype: Result: ALLOW Elapsed time: 488 ns Config: Additional Information: Found flow with id 143799, using existing flow … Phase: 6 Type: ADJACENCY-LOOKUP Subtype: Resolve Nexthop IP address to MAC Result: ALLOW Elapsed time: 1952 ns Config: Additional Information: Found adjacency entry for Next-hop 0.0.0.0 on interface identity Adjacency :Active MAC address 0000.0000.0000 hits 483359 reference 2 Result: input-interface: OUTSIDE(vrfid:0) input-status: up input-line-status: up output-interface: NP Identity Ifc Action: allow Time Taken: 18056 ns 1 packet shown
추적의 핵심 사항은 다음과 같습니다.
traceroute 테스트에서 인그레스 ICMP 패킷을 추적합니다.
패킷 #12은 트랜짓 호스트의 응답입니다.
firepower# show capture CAPI packet-number 12 trace
190 packets captured
12: 13:50:33.232562 802.1Q vlan#201 P0 192.168.201.88 > 192.168.201.200 icmp: time exceeded in-transit
Phase: 3
Type: UN-NAT
Subtype: static
Result: ALLOW
Elapsed time: 6344 ns
Config:
nat (INSIDE,OUTSIDE) source static server_host interface
Additional Information:
NAT divert to egress interface INSIDE(vrfid:0)
Untranslate 192.168.201.200/49168 to 192.168.200.50/49168
Phase: 7
Type: ACCESS-LIST
Subtype:
Result: ALLOW
Elapsed time: 97 ns
Config:
access-group CSM_FW_ACL_ global
access-list CSM_FW_ACL_ advanced permit ip any any rule-id 268436480
access-list CSM_FW_ACL_ remark rule-id 268436480: ACCESS POLICY: mzafeiro_empty - Default
access-list CSM_FW_ACL_ remark rule-id 268436480: L4 RULE: DEFAULT ACTION RULE
Additional Information:
This packet will be sent to snort for additional processing where a verdict will be reached
Phase: 18
Type: FLOW-CREATION
Subtype:
Result: ALLOW
Elapsed time: 16104 ns
Config:
Additional Information:
New flow created with id 143805, packet dispatched to next module
Phase: 20
Type: SNORT
Subtype: identity
Result: ALLOW
Elapsed time: 39496 ns
Config:
Additional Information:
user id: no auth, realm id: 0, device type: 0, auth type: invalid, auth proto: basic, username: none, AD domain: none,
src sgt: 0, src sgt type: unknown, dst sgt: 0, dst sgt type: unknown, abp src: none, abp dst: none, location: none
Result:
input-interface: OUTSIDE(vrfid:0)
input-status: up
input-line-status: up
output-interface: INSIDE(vrfid:0)
output-status: up
output-line-status: up
Action: allow
Time Taken: 158341 ns
이 경우 다음과 같은 고정 NAT 규칙으로 인해 문제가 발생합니다.
firepower# show run nat nat (INSIDE,OUTSIDE) source static server_host interface
| 개정 | 게시 날짜 | 의견 |
|---|---|---|
1.0 |
09-Apr-2026
|
최초 릴리스 |