Kumaha troubleshoot IPsec VPN domestik. Bagian 1

Kaayaan éta

Peré. Abdi nginum kopi. Murid nyetél sambungan VPN antara dua titik sareng ngaleungit. Kuring pariksa: bener aya torowongan, tapi euweuh lalulintas di torowongan. Murid teu ngajawab telepon.

Kuring nempatkeun ketel on na teuleum ka ngungkulan S-Terra Gateway. Kuring babagi pangalaman jeung metodologi kuring.

Sumber data

Dua situs anu dipisahkeun sacara geografis disambungkeun ku torowongan GRE. GRE kedah énkripsi:

Kuring pariksa pungsionalitas torowongan GRE. Jang ngalampahkeun ieu, kuring ngajalankeun ping ti alat R1 ka panganteur GRE alat R2. Ieu mangrupikeun target lalu lintas pikeun énkripsi. Taya jawaban:

root@R1:~# ping 1.1.1.2 -c 4
PING 1.1.1.2 (1.1.1.2) 56(84) bytes of data.

--- 1.1.1.2 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3057ms

Kuring nempo log on Gate1 jeung Gate2. Log éta kalayan senang ngalaporkeun yén torowongan IPsec suksés diluncurkeun, teu aya masalah:

root@Gate1:~# cat /var/log/cspvpngate.log
Aug  5 16:14:23 localhost  vpnsvc: 00100119 <4:1> IPSec connection 5 established, traffic selector 172.17.0.1->172.16.0.1, proto 47, peer 10.10.10.251, id "10.10.10.251", Filter 
IPsec:Protect:CMAP:1:LIST, IPsecAction IPsecAction:CMAP:1, IKERule IKERule:CMAP:1

Dina statistik torowongan IPsec dina Gate1 kuring ningali yén leres-leres aya torowongan, tapi konter Rсvd direset kana nol:

root@Gate1:~# sa_mgr show
ISAKMP sessions: 0 initiated, 0 responded

ISAKMP connections:
Num Conn-id (Local Addr,Port)-(Remote Addr,Port) State Sent Rcvd
1 3 (10.10.10.251,500)-(10.10.10.252,500) active 1070 1014

IPsec connections:
Num Conn-id (Local Addr,Port)-(Remote Addr,Port) Protocol Action Type Sent Rcvd
1 3 (172.16.0.1,*)-(172.17.0.1,*) 47 ESP tunn 480 0

Kuring nyusahkeun S-Terra kawas kieu: Kuring néangan dimana pakét target leungit dina jalur ti R1 mun R2. Dina prosés (spoiler) Kuring bakal manggihan kasalahan.

Pamérésan masalah

Lengkah 1. Naon Gate1 narima ti R1

Kuring nganggo sniffer pakét anu diwangun - tcpdump. Kuring ngaluncurkeun sniffer dina antarmuka internal (Gi0/1 dina notasi sapertos Cisco atanapi eth1 dina notasi Debian OS):

root@Gate1:~# tcpdump -i eth1

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 262144 bytes
14:53:38.879525 IP 172.16.0.1 > 172.17.0.1: GREv0, key=0x1, length 92: IP 1.1.1.1 > 1.1.1.2: ICMP echo request, id 2083, seq 1, length 64
14:53:39.896869 IP 172.16.0.1 > 172.17.0.1: GREv0, key=0x1, length 92: IP 1.1.1.1 > 1.1.1.2: ICMP echo request, id 2083, seq 2, length 64
14:53:40.921121 IP 172.16.0.1 > 172.17.0.1: GREv0, key=0x1, length 92: IP 1.1.1.1 > 1.1.1.2: ICMP echo request, id 2083, seq 3, length 64
14:53:41.944958 IP 172.16.0.1 > 172.17.0.1: GREv0, key=0x1, length 92: IP 1.1.1.1 > 1.1.1.2: ICMP echo request, id 2083, seq 4, length 64

Kuring nempo yén Gate1 narima pakét GRE ti R1. Kuring ngaléngkah.

lengkah 2. Naon Gate1 teu kalawan pakét GRE

Ngagunakeun utilitas klogview abdi tiasa ningali naon anu lumangsung kalawan pakét GRE jero supir S-Terra VPN:

root@Gate1:~# klogview -f 0xffffffff

filtration result for out packet 172.16.0.1->172.17.0.1, proto 47, len 112, if eth0: chain 4 "IPsecPolicy:CMAP", filter 8, event id IPsec:Protect:CMAP:1:LIST, status PASS
encapsulating with SA 31: 172.16.0.1->172.17.0.1, proto 47, len 112, if eth0
passed out packet 10.10.10.251->10.10.10.252, proto 50, len 160, if eth0: encapsulated

Kuring nempo yén udagan GRE lalulintas (proto 47) 172.16.0.1 -> 172.17.0.1 sumping dina aturan enkripsi LIST dina peta crypto CMAP sarta encapsulated. Salajengna, pakét dialihkeun (kaluar). Aya henteu lalulintas respon dina kaluaran klogview.

Kuring mariksa daptar aksés dina alat Gate1. Kuring ningali hiji daptar daptar aksés, anu netepkeun lalu lintas target pikeun enkripsi, anu hartosna aturan firewall henteu dikonpigurasi:

Gate1#show access-lists
Extended IP access list LIST
    10 permit gre host 172.16.0.1 host 172.17.0.1

Kacindekan: masalahna henteu sareng alat Gate1.

Langkung seueur ngeunaan klogview

Supir VPN nanganan sadaya lalu lintas jaringan, sanés ngan ukur lalu lintas anu kedah énkripsi. Ieu mangrupikeun pesen anu katingali dina klogview upami supir VPN ngolah lalu lintas jaringan sareng ngirimkeunana henteu énkripsi:

root@R1:~# ping 172.17.0.1 -c 4

root@Gate1:~# klogview -f 0xffffffff

filtration result for out packet 172.16.0.1->172.17.0.1, proto 1, len 84, if eth0: chain 4 "IPsecPolicy:CMAP": no match
passed out packet 172.16.0.1->172.17.0.1, proto 1, len 84, if eth0: filtered

Kuring nempo yén lalulintas ICMP (proto 1) 172.16.0.1-> 172.17.0.1 teu kaasup (euweuh cocok) dina aturan enkripsi tina kartu crypto CMAP. pakét ieu routed (lulus kaluar) dina téks jelas.

Lengkah 3. Naon Gate2 narima ti Gate1

Kuring ngaluncurkeun sniffer dina antarmuka WAN (eth0) Gate2:

root@Gate2:~# tcpdump -i eth0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:05:45.104195 IP 10.10.10.251 > 10.10.10.252: ESP(spi=0x30088112,seq=0x1), length 140
16:05:46.093918 IP 10.10.10.251 > 10.10.10.252: ESP(spi=0x30088112,seq=0x2), length 140
16:05:47.117078 IP 10.10.10.251 > 10.10.10.252: ESP(spi=0x30088112,seq=0x3), length 140
16:05:48.141785 IP 10.10.10.251 > 10.10.10.252: ESP(spi=0x30088112,seq=0x4), length 140

Kuring ningali yén Gate2 nampi pakét ESP ti Gate1.

Lengkah 4. Naon Gate2 teu jeung bungkusan ESP

Kuring ngajalankeun utiliti klogview on Gate2:

root@Gate2:~# klogview -f 0xffffffff
filtration result for in packet 10.10.10.251->10.10.10.252, proto 50, len 160, if eth0: chain 17 "FilterChain:L3VPN", filter 21, status DROP
dropped in packet 10.10.10.251->10.10.10.252, proto 50, len 160, if eth0: firewall

Kuring nempo yén pakét ESP (proto 50) turun (DROP) ku aturan firewall (L3VPN). Kuring mastikeun yén Gi0/0 saleresna ngagaduhan daptar aksés L3VPN anu napel na:

Gate2#show ip interface gi0/0
GigabitEthernet0/0 is up, line protocol is up
  Internet address is 10.10.10.252/24
  MTU is 1500 bytes
  Outgoing access list is not set
  Inbound  access list is L3VPN

Kuring manggihan masalah.

Lengkah 5. Naon salahna daptar aksés

Kuring ningali naon daptar aksés L3VPN:

Gate2#show access-list L3VPN
Extended IP access list L3VPN
    10 permit udp host 10.10.10.251 any eq isakmp
    20 permit udp host 10.10.10.251 any eq non500-isakmp
    30 permit icmp host 10.10.10.251 any

Kuring ningali yén pakét ISAKMP diidinan, janten torowongan IPsec diadegkeun. Tapi teu aya aturan anu ngamungkinkeun pikeun ESP. Tétéla, murid bingung icmp na esp.

Ngédit daptar aksés:

Gate2(config)#
ip access-list extended L3VPN
no 30
30 permit esp host 10.10.10.251 any

Lengkah 6. Mariksa fungsionalitas

Anu mimiti, kuring mastikeun yén daptar aksés L3VPN leres:

Gate2#show access-list L3VPN
Extended IP access list L3VPN
    10 permit udp host 10.10.10.251 any eq isakmp
    20 permit udp host 10.10.10.251 any eq non500-isakmp
    30 permit esp host 10.10.10.251 any

Ayeuna kuring ngajalankeun lalulintas target tina alat R1:

root@R1:~# ping 1.1.1.2 -c 4
PING 1.1.1.2 (1.1.1.2) 56(84) bytes of data.
64 bytes from 1.1.1.2: icmp_seq=1 ttl=64 time=35.3 ms
64 bytes from 1.1.1.2: icmp_seq=2 ttl=64 time=3.01 ms
64 bytes from 1.1.1.2: icmp_seq=3 ttl=64 time=2.65 ms
64 bytes from 1.1.1.2: icmp_seq=4 ttl=64 time=2.87 ms

--- 1.1.1.2 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3006ms
rtt min/avg/max/mdev = 2.650/10.970/35.338/14.069 ms

meunangna. Torowongan GRE parantos diadegkeun. Kontra lalu lintas asup dina statistik IPsec henteu nol:

root@Gate1:~# sa_mgr show
ISAKMP sessions: 0 initiated, 0 responded

ISAKMP connections:
Num Conn-id (Local Addr,Port)-(Remote Addr,Port) State Sent Rcvd
1 3 (10.10.10.251,500)-(10.10.10.252,500) active 1474 1350

IPsec connections:
Num Conn-id (Local Addr,Port)-(Remote Addr,Port) Protocol Action Type Sent Rcvd
1 4 (172.16.0.1,*)-(172.17.0.1,*) 47 ESP tunn 1920 480

Dina gateway Gate2, dina kaluaran klogview, pesen muncul yén udagan lalulintas 172.16.0.1-> 172.17.0.1 suksés didekripsi (LULUS) ku aturan LIST dina peta crypto CMAP:

root@Gate2:~# klogview -f 0xffffffff
filtration result for in packet 172.16.0.1->172.17.0.1, proto 47, len 112, if eth0: chain 18 "IPsecPolicy:CMAP", filter 25, event id IPsec:Protect:CMAP:1:LIST, status PASS
passed in packet 172.16.0.1->172.17.0.1, proto 47, len 112, if eth0: decapsulated

hasil

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