09-17-2014 12:52 PM - edited 02-21-2020 07:50 PM
Hi All,
I have an IKEv1 IPSEC L2L tunnel setup between a 5525x ASA and a 5510 ASA both running 9.1(5), and am having trouble with asymmetric decryption at one side of the tunnel.
I have a very simple one line crypto ACL which permits a /24 subnet to talk to a /20 and vice versa, I have checked all the relevant NO NAT's are in place, they are, as is the routing.
The ISAKMP SA's are all in place and look good (sanitized).
IKEv1 SAs:
Active SA: 1
Rekey SA: 0 (A tunnel will report 1 Active and 1 Rekey SA during rekey)
Total IKE SA: 1
1 IKE Peer: 1.1.1.1
Type : L2L Role : responder
Rekey : no State : MM_ACTIVE
There are no IKEv2 SAs
On the 5510, I can see that arriving traffic is being decrypted from the 5525x ok, and is being encrypted outbound toward the 5525x as well, again this looks good.
interface: outside
Crypto map tag: outside_map, seq num: 1, local addr: 2.2.2.2
access-list outside_cryptomap extended permit ip 10.20.0.0 255.255.255.0 10.1.64.0 255.255.240.0
local ident (addr/mask/prot/port): (10.20.0.0/255.255.255.0/0/0)
remote ident (addr/mask/prot/port): (10.1.64.0/255.255.240.0/0/0)
current_peer: 1.1.1.1
#pkts encaps: 54, #pkts encrypt: 54, #pkts digest: 54
#pkts decaps: 411, #pkts decrypt: 411, #pkts verify: 411
#pkts compressed: 0, #pkts decompressed: 0
#pkts not compressed: 54, #pkts comp failed: 0, #pkts decomp failed: 0
#pre-frag successes: 0, #pre-frag failures: 0, #fragments created: 0
#PMTUs sent: 0, #PMTUs rcvd: 0, #decapsulated frgs needing reassembly: 0
#TFC rcvd: 0, #TFC sent: 0
#Valid ICMP Errors rcvd: 0, #Invalid ICMP Errors rcvd: 0
#send errors: 0, #recv errors: 0
local crypto endpt.: 2.2.2.2/0, remote crypto endpt.: 1.1.1.1/0
path mtu 1500, ipsec overhead 58(36), media mtu 1500
PMTU time remaining (sec): 0, DF policy: copy-df
ICMP error validation: disabled, TFC packets: disabled
current outbound spi: 1CDEA655
current inbound spi : A60AA787
inbound esp sas:
spi: 0xA60AA787 (2785716103)
transform: esp-3des esp-sha-hmac no compression
in use settings ={L2L, Tunnel, PFS Group 2, IKEv1, }
slot: 0, conn_id: 278528, crypto-map: outside_map
sa timing: remaining key lifetime (kB/sec): (4373917/27576)
IV size: 8 bytes
replay detection support: Y
Anti replay bitmap:
0xFFFFFFFF 0xFFFFFFFF
outbound esp sas:
spi: 0x1CDEA655 (484353621)
transform: esp-3des esp-sha-hmac no compression
in use settings ={L2L, Tunnel, PFS Group 2, IKEv1, }
slot: 0, conn_id: 278528, crypto-map: outside_map
sa timing: remaining key lifetime (kB/sec): (4373985/27576)
IV size: 8 bytes
replay detection support: Y
Anti replay bitmap:
0x00000000 0x00000001
The output of the show crypto ipsec accelerator stats on the 5510 gives this... which seems to show that stuff is going in and out ok via the hardware engine in slot 1
Crypto Accelerator Status
-------------------------
[Capability]
Supports hardware crypto: True
Supports modular hardware crypto: False
Max accelerators: 2
Max crypto throughput: 170 Mbps
Max crypto connections: 250
[Global Statistics]
Number of active accelerators: 2
Number of non-operational accelerators: 0
Input packets: 523405
Input bytes: 111848159
Output packets: 230595
Output error packets: 0
Output bytes: 230240311
[Accelerator 0]
Status: OK
Software crypto engine
Slot: 0
Active time: 986957 seconds
Total crypto transforms: 13635
Total dropped packets: 0
[Input statistics]
Input packets: 0
Input bytes: 51856
Input hashed packets: 0
Input hashed bytes: 0
Decrypted packets: 0
Decrypted bytes: 51856
[Output statistics]
Output packets: 0
Output bad packets: 0
Output bytes: 109776
Output hashed packets: 0
Output hashed bytes: 0
Encrypted packets: 0
Encrypted bytes: 109984
[Diffie-Hellman statistics]
Keys generated: 0
Secret keys derived: 0
[RSA statistics]
Keys generated: 1
Signatures: 6
Verifications: 1
Encrypted packets: 1
Encrypted bytes: 28
Decrypted packets: 1
Decrypted bytes: 256
[ECDSA statistics]
Keys generated: 12
Signatures: 12
Verifications: 15
[SSL statistics]
Outbound records: 0
Inbound records: 0
[RNG statistics]
Random number requests: 71
Random number request failures: 0
[HMAC statistics]
HMAC requests: 3222
[Accelerator 1]
Status: OK
Encryption hardware device : Cisco ASA-55xx on-board accelerator (revision 0x0)
Boot microcode : CN1000-MC-BOOT-2.00
SSL/IKE microcode : CNLite-MC-SSLm-PLUS-2_05
IPSec microcode : CNlite-MC-IPSECm-MAIN-2.09
Slot: 1
Active time: 986963 seconds
Total crypto transforms: 1253215
Total dropped packets: 0
[Input statistics]
Input packets: 523436
Input bytes: 128675042
Input hashed packets: 357595
Input hashed bytes: 81336891
Decrypted packets: 523439
Decrypted bytes: 96027422
[Output statistics]
Output packets: 230669
Output bad packets: 0
Output bytes: 442975336
Output hashed packets: 32674
Output hashed bytes: 9898376
Encrypted packets: 230677
Encrypted bytes: 228312109
[Diffie-Hellman statistics]
Keys generated: 216
Secret keys derived: 55
[RSA statistics]
Keys generated: 0
Signatures: 1
Verifications: 1
Encrypted packets: 2
Encrypted bytes: 63
Decrypted packets: 2
Decrypted bytes: 512
[ECDSA statistics]
Keys generated: 0
Signatures: 0
Verifications: 0
[SSL statistics]
Outbound records: 198027
Inbound records: 165862
[RNG statistics]
Random number requests: 235
Random number request failures: 0
[HMAC statistics]
HMAC requests: 99983
on the 5525x side, I see traffic leaving outbound is encrypted ok, but nothing is being decrypted inbound, from the 5510. There is only one IPSEC VPN configured on each ASA and in essence , there isn't much to go wrong it would appear.
The crypto IPSEC SA on the 5525x looks like this... again ok, apart from the obvious lack of inbound decryption...
interface: outside
Crypto map tag: outside_map, seq num: 1, local addr: 1.1.1.1
access-list outside_cryptomap_1 extended permit ip 10.1.64.0 255.255.240.0 10.20.0.0 255.255.255.0
local ident (addr/mask/prot/port): (10.1.64.0/255.255.240.0/0/0)
remote ident (addr/mask/prot/port): (10.20.0.0/255.255.255.0/0/0)
current_peer: 2.2.2.2
#pkts encaps: 607, #pkts encrypt: 607, #pkts digest: 607
#pkts decaps: 0, #pkts decrypt: 0, #pkts verify: 0
#pkts compressed: 0, #pkts decompressed: 0
#pkts not compressed: 607, #pkts comp failed: 0, #pkts decomp failed: 0
#pre-frag successes: 0, #pre-frag failures: 0, #fragments created: 0
#PMTUs sent: 0, #PMTUs rcvd: 0, #decapsulated frgs needing reassembly: 0
#TFC rcvd: 0, #TFC sent: 0
#Valid ICMP Errors rcvd: 0, #Invalid ICMP Errors rcvd: 0
#send errors: 0, #recv errors: 0
local crypto endpt.: 1.1.1.1/0, remote crypto endpt.: 2.2.2.2/0
path mtu 1500, ipsec overhead 58(36), media mtu 1500
PMTU time remaining (sec): 0, DF policy: copy-df
ICMP error validation: disabled, TFC packets: disabled
current outbound spi: A60AA787
current inbound spi : 1CDEA655
<--- More --->
inbound esp sas:
spi: 0x1CDEA655 (484353621)
transform: esp-3des esp-sha-hmac no compression
in use settings ={L2L, Tunnel, PFS Group 2, IKEv1, }
slot: 0, conn_id: 495616, crypto-map: outside_map
sa timing: remaining key lifetime (kB/sec): (3915000/26998)
IV size: 8 bytes
replay detection support: Y
Anti replay bitmap:
0x00000000 0x00000001
outbound esp sas:
spi: 0xA60AA787 (2785716103)
transform: esp-3des esp-sha-hmac no compression
in use settings ={L2L, Tunnel, PFS Group 2, IKEv1, }
slot: 0, conn_id: 495616, crypto-map: outside_map
sa timing: remaining key lifetime (kB/sec): (3914877/26998)
IV size: 8 bytes
replay detection support: Y
Anti replay bitmap:
0x00000000 0x00000001
And this is the show ipsec accelerator from the 5525x... It shows the same, apart from on accelerator 1, it actually appears to show inbound packets are being received, but none of them are subject to hashing, Im not sure if this is the problem itself or just symptomatic of something else, but it does suggest to me that the traffic is arriving ok, but just not being decrypted properly for some reason, there are no errors noted on either side either
Crypto Accelerator Status
-------------------------
[Capability]
Supports hardware crypto: True
Supports modular hardware crypto: False
Max accelerators: 2
Max crypto throughput: 750 Mbps
Max crypto connections: 750
[Global Statistics]
Number of active accelerators: 2
Number of non-operational accelerators: 0
Input packets: 840012
Input bytes: 128403377
Output packets: 1658183
Output error packets: 0
Output bytes: 1212761705
[Accelerator 0]
Status: OK
Software crypto engine
Slot: 0
Active time: 1051309 seconds
Total crypto transforms: 48246
Total dropped packets: 0
<--- More --->
[Input statistics]
Input packets: 0
Input bytes: 118048
Input hashed packets: 0
Input hashed bytes: 0
Decrypted packets: 0
Decrypted bytes: 118048
[Output statistics]
Output packets: 0
Output bad packets: 0
Output bytes: 462400
Output hashed packets: 0
Output hashed bytes: 0
Encrypted packets: 0
Encrypted bytes: 462608
[Diffie-Hellman statistics]
Keys generated: 0
Secret keys derived: 0
[RSA statistics]
Keys generated: 4
Signatures: 12
Verifications: 1
Encrypted packets: 1
Encrypted bytes: 28
<--- More --->
Decrypted packets: 1
Decrypted bytes: 256
[ECDSA statistics]
Keys generated: 12
Signatures: 12
Verifications: 15
[SSL statistics]
Outbound records: 0
Inbound records: 0
[RNG statistics]
Random number requests: 300
Random number request failures: 0
[HMAC statistics]
HMAC requests: 11438
[Accelerator 1]
Status: OK
Encryption hardware device : Cisco ASA-55xx on-board accelerator (revision 0x1)
Boot microcode : CNPx-MC-BOOT-2.00
SSL/IKE microcode : CNPx-MC-SSL-PLUS-T020
IPSec microcode : CNPx-MC-IPSEC-MAIN-0026
Slot: 1
Active time: 1051314 seconds
Total crypto transforms: 3032742
<--- More --->
Total dropped packets: 0
[Input statistics]
Input packets: 840077
Input bytes: 249823866
Input hashed packets: 0
Input hashed bytes: 0
Decrypted packets: 840077
Decrypted bytes: 128290297
[Output statistics]
Output packets: 1658289
Output bad packets: 0
Output bytes: 2316734504
Output hashed packets: 377909
Output hashed bytes: 89053304
Encrypted packets: 1658294
Encrypted bytes: 1191185759
[Diffie-Hellman statistics]
Keys generated: 225
Secret keys derived: 65
[RSA statistics]
Keys generated: 0
Signatures: 1
Verifications: 1
Encrypted packets: 2
<--- More --->
Encrypted bytes: 63
Decrypted packets: 2
Decrypted bytes: 512
[ECDSA statistics]
Keys generated: 0
Signatures: 0
Verifications: 0
[SSL statistics]
Outbound records: 1280408
Inbound records: 840095
[RNG statistics]
Random number requests: 4010
Random number request failures: 0
[HMAC statistics]
HMAC requests: 106437
Not sure whats going on here but I have tried tearing stuff down, removing and reapplying cryptos, entire VPN configs removed and replaced, different transform sets, quadruple checked routing and nats and it all looks ok.
So to summarise, it looks like traffic is leaving the 5525x through the tunnel, arriving at the 5510, being successfully decrypted and turned around by the host (have proved this with a traffic capture on the 5510 LAN side), encrypted by the 5510, sent the the 5525x where it fails to be decrypted correctly. The same goes for traffic which originates from the LAN side of the 5510.
Any ideas would be gratefully appreciated.
Cheers
Shaun
09-18-2014 11:17 AM
Anyone have any suggestions ?
09-22-2014 02:20 AM
Hi,
Can you take a capture on the device where decaps is 0, between the source and destination peer IP(outside IPs) on the outside interface( an interface where VPN terminates). Check if you have ESP packets recieved. if you don't see an ESP packets then it might be an ISP issue( blocking ESP ) on the remote end.
-Altaf
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