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IPSec Troubleshooting

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IPSec Troubleshooting

Last adaptation to the version: 12.6.0

New:
  • Updated to Redesign of the webinterface
  • The log level can be set directly in the admin interface
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This article refers to a Resellerpreview
Access: UTM-IP:Port or UTM-URL:Port
Port as configured at Network / Appliance Settings / Webserver
Default-Port: 11115
i.e.: https://utm.ttt-point.de:11115
Default: https://192.168.175.1:11115 VPN IPSec  Area Log Button
IPSec Log


Preparation - Increase log level

Log

As a prerequisite for successful troubleshooting, the log level must first be increased.

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When the log level is changed, the IPSec service is restarted. All IPSec connections are interrupted once during this process.
Log-Level: Rudimentary (recommended) Default IPSec UTMuser@firewall.name.fqdnVPN IPSec Log Save and restart UTM v12.6 IPSec Log-en.png
Log
Section Log with
General
 and expanded
[–] Advanced Settings
Detailed Suitable for detailed troubleshooting
very detailed May be required for specific troubleshooting
  • This setting generates an excessive number of messages, so that the log will reach its limit within a very short time and, as a result, messages will have to be deleted more quickly. Important messages (from other services) may be overlooked. It is recommended not to use this setting or to use it only for a short time.
    • User-defined All values can be logged in the
    [–] Advanced Settings
     section in 5 different levels
    Save the changed settings with
    Save and restart
  • This restarts the IPSec service and briefly interrupts all IPSec connections once.
    • Alternative option to change the log level:

    CLI command

    Extras CLI extc value set application "ipsec" variable "DBG_LVL_IKE" value [ "2" ]
  • IPSec service must then be restarted. This interrupts all IPSec connections!

    appmgmt restart application ipsec

    • Alternative option to change the log level:

    Set extc-variable

    In the advanced settings:
    Displayable via Strg + Alt + A

    Extras Advanced Settings  Area extc-variables search for variable DBG_LVL_IKE and change value to »2
  • IPSec service must then be restarted. This interrupts all IPSec connections!

    Menu Applications Application status Application IPSec Button

    • Alternative option to change the log level:

    SSH

    via SSH at runtime as root
  • Here the IPSec service does not have to be restarted.
    • * (only up to version 12.1.8):
    ipsec stroke loglevel ike 2
    This command returns the setting to its original value after a restart!

    * (as of version 12.2):
    spcli extc value set application ipsec variable DBG_LVL_IKE value 2
    spcli appmgmt config
    swanctl --reload-settings



    IKEv1 Troubleshooting

    The establishment of an IPSec connection using IKEv1 takes place in two phases. In phase 1, both gateways are authenticated against each other. This can be done in two different ways: The "Aggressive Mode" or the "Main Mode". The aggressive mode encrypts the Pre Shared Key (PSK) using a simple hash algorithm.

    Apart from this PSK, no further identification is provided. This results in the following disadvantages:

    • When several remote stations are connected, they cannot be distinguished from each other in phase 1. Therefore, the same PSK must be used in all connections. The probability of being compromised increases with the number of remote stations.
    • The simple hash encryption of the PSK makes it vulnerable to dictionary attacks, and more so the simpler it is. Since no other identification feature is provided besides the PSK, such attacks can be carried out by any computer with Internet access.

    For these reasons, the aggressive mode of IPSec does not find any use in connection with Securepoint NextGen UTM. Only the secure main mode is used. In addition to the PSK, this requires a further identification feature, the so-called ID. Furthermore, the transmission of the PSK is secured by the Diffie-Hellman key exchange method. This makes it mathematically impossible to intercept a transmitted key. In addition to PSKs, the main mode also allows RSA keys or X.509 certificates for authentication.

    		Ipsec troubleshooting01.png

    Phase 1

    The normal connection setup
    If no errors occur in phase 1, this is indicated by an entry in the LiveLog that reports the successful establishment of an IKE_SA. If this entry is found in both the initiator's log and the responder's log, phase 1 has been configured without errors and any configuration error should be looked for in phase 2.
    Service Message
    IPSec 10[IKE] IKE_SA Standort_1_2[1] established between 198.51.100.75[198.51.100.75]...198.51.100.1[198.51.100.1]
    False proposal
    If both sides cannot agree on encryption parameters acceptable to both sides, the responder reports this in its livelog.
    The initiator gets the message "NO_PROPOSAL_CHOSEN".
    Initiator-Log
    Service Message
    IPSec 10[IKE] received NO_PROPOSAL_CHOSEN notify error
    Responder-Log
    Service Message
    IPSec 05[CFG] selecting proposal:
    IPSec 05[CFG] no acceptable ENCRYPTION_ALGORITHM found
    IPSec 05[CFG] selecting proposal:
    IPSec 05[CFG] received proposals: IKE: BLOWFISH_CBC_256 / HMAC_SHA2_512_256 / PRF_HMAC_SHA2_512 / MODP_8192
    IPSec 05[CFG] configured proposals: IKE: AES_CBC_128 / HMAC_SHA2_256_128 / PRF_HMAC_SHA2_256 / MODP_2048, IKE: AES_CBC_128 / AES_CBC_192 / AES_CBC_256 / 3DES_CBC / CAMELLIA_CBC_128 / CAMELLIA_CBC_192 / CAMELLIA_CBC_256 / AES_CTR_128 / AES_CTR_192 / AES_CTR_256 / CAMELLIA_CTR_128 / CAMELLIA_CTR_192 / CAMELLIA_CTR_256 / HMAC_MD5_96 / HMAC_SHA1_96 / HMAC_SHA2_256_128 / HMAC_SHA2_384_192 / HMAC_SHA2_512 / AES_XCBC_96 / AES_CMAC_96 / PRF_HMAC_MD5 / PRF_HMAC_SHA1 / PRF_HMAC_SHA2_256 / PRF_HMAC_SHA2_512 / 256 / AES_XCBC_96 / AES_CMAC_96 / PRF_AES128_CMAC / MODP_2048 / MODP_2048_224 / MODP_2048_256 / MODP_1536 / MODP_3072 / MODP_4096 / MODP_8192 / MODP_1024 / MODP_1024_160 / ECP_256 / ECP_384 / ECP_512 / ECP_224 / ECP_192 / ECP_224_BP / ECP_256_BP / ECP_384_BP_ECP_512_BP , IKE: AES_GCM_8_128 / AES_GCM_8_192 / AES_GCM_8_256 / AES_GCM_12_128 / AES_GCM_12_192 / AES_GCM_12_256 / AES_GCM_16_128 / AES_GCM_16_192 / AES_GCM_16_256 / PRF_HMAC_MD5 / PRF_HMAC_SHA1 / PRF_HMAC_SHA2_256 / PRF_HMAC_SHA2_384 / PRF_HMAC_SHA2_512 / PRF_AES128_XCBC / PRF_AES128_CMAC / MODP_2048 / MODP_2048_224 / MODP_2048_256 / MODP_1536 / MODP_3072 / MODP_4096 / MODP_8192 / MODP_1024 / MODP_1024_160 / ECP_256 / ECP_384 / ECP__521 / ECP_224 / ECP_192 / ECP_224_BP / ECP_256_BP / ECP_384_BP / ECP_512_BP
    IPSec 10[IKE] received proposals inacceptable
    Incorrect remote gateway address
    If the initiator attempts to establish a connection from a gateway address other than the one configured on the responder side, the responder cannot classify this connection. This is reported accordingly in the LiveLog.
    The initiator gets the message NO_PROPOSAL_CHOSEN.
    Responder-Log
    Service Message
    IPSec 11[CFG] looking for an ike config for 198.51.100.75...195.51.100.1
    IPSec 11[IKE] no IKE config found for 198.51.100.75...195.51.100.1, sending NO_PROPOSAL_CHOSEN
    Incorrect ID Initiator
    If the initiator logs in with an identifier (ID) other than the one stored in the responder's configuration, the responder cannot determine a PSK configuration for this connection attempt and reports this accordingly in the LiveLog.
    The initiator receives the error message AUTHENTICATION_FAILED.
    Initiator-Log
    Service Message
    IPSec 09[IKE] received AUTHENTICATION_FAILED error notify
    Responder-Log
    Service Message
    IPSec 07[CFG] looking for pre-shared key peer configs matching 198.51.100.75...198.51.100.1[blubb]
    IPSec 07[IKE] no peer config found
    Incorrect ID Responder
    If the responder reports with a different ID than in the initiator's configuration, then this is reported accordingly in the initiator's log.
    Initiator-Log
    Service Message
    IPSec 05[IKE] IDir 'blubb' does not match to '198.51.100.75'
    Incorrect PSK
    In contrast to older software versions, there is no clearly readable hint in the log for mismatched PSKs when using IKEv1. Indirectly, the indication of "malformed" packets points to this error.
    Initiator-Log
    Service Message
    IPSec 15[IKE] message parsing failed
    IPSec 15[IKE] ignore malformed INFORMATIONAL request
    IPSec 15[IKE] INFORMATIONAL_V1 request with message ID 1054289493 processing failed
    Responder-Log
    Service Message
    IPSec 14[IKE] message parsing failed
    IPSec 14[IKE] ID_PROT request with message ID 0 processing failed
    Incorrect RSA key initiator
    If the initiator of the connection uses a different RSA key than the one set in the responder configuration, authentication cannot take place.
    The initiator receives the error message "AUTHENTICATION_FAILED".
    Initiator-Log
    Service Message
    IPSec 15[IKE] authentication of 'Filiale' (myself) succesful
    IPSec 16[IKE] received AUTHENTICATION_FAILED error notify
    Responder-Log
    Service Message
    IPSec 14[CFG] looking for RSA signature peer configs matching 198.51.100.75...198.51.100.1[Filiale]
    IPSec 14[CFG] candidate "Standort1_4", match: 1/20/28 (me/other/ike)
    IPSec 14[CFG] selected peer config "Standort1_4"
    IPSec 14[CFG] using trusted certificate "Filiale"
    IPSec 14[IKE] ignature validation failed, looking for another key
    IPSec 14[IKE] no trusted RSA public key found for 'Filiale'
    Incorrect RSA key responder
    If the responder uses a different RSA key than the one specified in the initiator's configuration, the authentication fails again on the initiator's side. The responder that has already established an IKE_SA is instructed to delete it again.
    Initiator-Log
    Service Message
    IPSec 16[CFG] authentication of 'Filiale' (myself) succesful
    IPSec 16[IKE] using trusted certificate "Zentrale"
    IPSec 16[IKE] signature validation failed, looking for another key
    IPSec 15[IKE] no trusted RSA public key found for 'Zentrale'
    Responder-Log
    Service Message
    IPSec 10[CFG] looking for RSA signature peer configs matching 198.51.100.75...198.51.100.1[Filiale]
    IPSec 10[CFG] candidate "Standort1_4", match: 1/20/28 (me/other/ike)
    IPSec 10[CFG] selected peer config "Standort1_4"
    IPSec 10[CFG] using trusted certificate "Filiale"
    IPSec 10[IKE] authentication of 'Filiale' with RSA succesful
    IPSec 10[IKE] authentication of 'Zentrale' (myself) succesful
    IPSec 10[IKE] IKE_SA Standort1_4[1] established between 198.51.100.75[Zentrale]...198.51.100.1[Filiale]
    IPSec 10[IKE] IKE_SA Standort1_4[1] established between 198.51.100.75[Zentrale]...198.51.100.1[Filiale]
    IPSec 10[IKE] scheduling reauthentication in 2593s
    IPSec 10[IKE] maximum IKE_SA lifetime 3133s
    IPSec 13[IKE] received DELETE for IKE_SA Standort_4[1]

    Phase 2

    The normal connection setup
    If phase 2 is also configured correctly, the successful establishment of a CHILD_SA is documented in the livelog of both sides.
    Initiator-Log & Responder-Log
    Service Message
    IPSec 05[IKE] CHILD_SA Zentrale_2{1} established with SPIs ca7520e3_i c562f9d6_o and TS 10.1.10.0/24 === 10.0.0.0/24
    IPSec 05[IKE] CHILD_SA Zentrale_2{1} established with SPIs ca7520e3_i c562f9d6_o and TS 10.1.10.0/24 === 10.0.0.0/24
    Incorrect subnet configuration
    If the configured subnets (the so-called traffic selectors) do not match in phase 2 of the initiator and responder, no tunnel can be set up on the previously established IKE_SA, i.e., no CHILD_SA is established. This information can be found in the responder's livelog.
    Initiator-Log
    Service Message
    IPSec 13[CFH] proposing traffic selectors for us:
    IPSec 13[CFG] 10.1.0.0/24
    IPSec 13[CFG] proposing traffic selectors for other:
    IPSec 13[CFG] 11.0.0.0/24
    IPSec 05[IKE] received INVALID_ID_INFORMATION error notify
    Responder-Log
    Service Message
    IPSec 11[CFG] looking for a child config for 11.0.0.0/24 === 10.1.0.0/24
    IPSec 11[CFG] proposing traffic selectors for us:
    IPSec 11[CFG] 10.0.0.0/24
    IPSec 11[CFG] proposing traffic selectors for other:
    IPSec 11[CFG] 10.1.0.0/24
    IPSec 11[IKE] no matching CHILD_SA config found


    IKEv2 Troubleshooting

    The establishment of the connection with IKEv2 has been drastically simplified compared to IKEv1. It is now no longer divided into phase 1 (authentication) and phase 2 (tunnel establishment); instead, one message pair is used to exchange first the proposals and DH keys and then the authentication and the traffic selectors (subnets). This makes the connection setup easier and less susceptible to interference. Ipsec troubleshooting10.png
    IKEv2 connection setup

    Connection setup

    Connection is established
    Initiator-Log & Responder-Log
    Service Message
    IPSec 11[CFG] selected proposal_ ESP_AES_CBC_128/HMAC_SHA2_256_128/NO_EXT_SEQ
    IPSec 11[CFG] selecting traffic selectors for us:
    IPSec 11[CFG] config: 10.1.0.0/24, received: 10.1.0.0/24 => match: 10.1.0.0/24
    IPSec 11[CFG] selecting traffic selectors for ther:
    IPSec 11[CFG] config: 10.0.0.0/24, received: 10.0.0.0/24 0 => match: 10.0.0.0/24
    IPSec 11[IKE] CHILD_SA Zentrale_3{2} established with SPIs c24bb346_i c8e52c94_o and T S 10.1.0.0/24 === 10.0.0.0/24
    IPSec 11[IKE] CHILD_SA Zentrale_3{2} established with SPIs c24bb346_i c8e52c94_o and T S 10.1.0.0/24 === 10.0.0.0/24
    Incorrect remote gateway address
    If the gateway address of the initiator and the remote gateway address specified in the responder configuration do not match, the connection attempt cannot be assigned. This is reported in the responder's log.
    The initiator receives the error message "NO_PROPOSAL_CHOSEN".
    Responder-Log
    Service Message
    IPSec 11[CFG] looking for an ike config fo 198.51.100.75...198.51.100.1
    IPSec 11[IKE] no IKE config for 198.51.100.75...198.51.100.1, sending NO_PROPOSAL_CHOSEN
    Incorrect ID Initiator
    If the configured remote ID does not match the ID reported by the initiator, the connection attempt cannot be assigned here either and is documented in the responder log.
    The initiator gets the error message AUTHENTICATION_FAILED.
    Initiator-Log
    Service Message
    IPSec 09[IKE] received AUTHENTICATION_FAILED error notify
    Responder-Log
    Service Message
    IPSec 07[CFG] looking for pre-shared key peer configs matching 198.51.100.75...198.51.100.1[blubb]
    IPSec 07[IKE] no peer config found
    Incorrect ID Responder
    Vice versa, a responder ID other than the one configured at the initiator is reported accordingly in the initiator's log.
    Initiator-Log
    Service Message
    IPSec 05[IKE] IDir 'blubb' does not match to '198.51.100.75'
    Incorrect PSK
    Initiator-Log
    Service Message
    IPSec 13[IKE] received AUTHENTICATION_FAILED notify error
    Responder-Log
    Service Message
    IPSec 10[IKE] tried 2 shared keys for '198.51.100.75' - '198.51.100.1', but MAC mismatched
    Incorrect subnet configuration
    If the configured subnets (the so-called traffic selectors) of initiator and responder do not match in the second step, no tunnel can be set up on the previously established IKE_SA, i.e., no CHILD_SA is established. This information can be found in the responder's livelog.
    Initiator-Log
    Service Message
    IPSec 10[IKE] received T S_UNACCEPTABLE notify, no CHILD_SA built
    IPSec 10[IKE] failed to establish CHILD_SA, keeping IKE_SA
    Responder-Log
    Service Message
    IPSec 05[CFG] looking for a child config for 10.0.0.0/24 === 11.1.0.0/24
    IPSec 05[CFG] proposing traffic selectors for us:
    IPSec 05[CFG] 10.0.0.0/24
    IPSec 05[CFG] proposing traffic selectors for other:
    IPSec 05[CFG] 10.1.0.0/24
    IPSec 10[IKE] traffic selectors 10.0.0.0/24 === 11.1.0.0/24 inacceptable
    IPSec 10[IKE] failed to establish CHILD_SA, keeping IKE_SA
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