EdgeRouter L2TP VPN can't pass IKE phase 1

JaredBusch

This is a working configuration I use on many routers.

L2TP config:

set vpn l2tp remote-access authentication local-users username SomeUsername password 'SomeUserPassword'
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access client-ip-pool start 10.254.203.2
set vpn l2tp remote-access client-ip-pool stop 10.254.203.10
set vpn l2tp remote-access dhcp-interface eth0
set vpn l2tp remote-access dns-servers server-1 1.1.1.1
set vpn l2tp remote-access dns-servers server-2 8.8.8.8
set vpn l2tp remote-access idle 1800
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret SomeGoodPSK
set vpn l2tp remote-access ipsec-settings ike-lifetime 3600
set vpn l2tp remote-access ipsec-settings lifetime 3600
set vpn l2tp remote-access mtu 1492

If your WAN port is not DHCP, then you use this line instead of the dhcp-interface line above.

set vpn l2tp remote-access outside-address your.wan.IP.add

IPSEC Config:

set vpn ipsec auto-firewall-nat-exclude enable
set vpn ipsec esp-group bnaesp compression disable
set vpn ipsec esp-group bnaesp lifetime 3600
set vpn ipsec esp-group bnaesp mode tunnel
set vpn ipsec esp-group bnaesp pfs enable
set vpn ipsec esp-group bnaesp proposal 1 encryption aes256
set vpn ipsec esp-group bnaesp proposal 1 hash sha1
set vpn ipsec ike-group bnaike ikev2-reauth no
set vpn ipsec ike-group bnaike key-exchange ikev1
set vpn ipsec ike-group bnaike lifetime 28800
set vpn ipsec ike-group bnaike proposal 1 dh-group 19
set vpn ipsec ike-group bnaike proposal 1 encryption aes256
set vpn ipsec ike-group bnaike proposal 1 hash sha1
set vpn ipsec ipsec-interfaces interface eth0
<snip about 8 tunnels>

Firewall Config:
Note, by using this firewall configuration, I do not need any other rules for L2TP. But this could be tighter as noted in the guide you followed.

set firewall name WAN_LOCAL rule 40 action accept
set firewall name WAN_LOCAL rule 40 description 'Allow IPSEC'
set firewall name WAN_LOCAL rule 40 ipsec match-ipsec
set firewall name WAN_LOCAL rule 40 log disable
set firewall name WAN_LOCAL rule 40 protocol all
set firewall name WAN_LOCAL rule 40 state established disable
set firewall name WAN_LOCAL rule 40 state invalid disable
set firewall name WAN_LOCAL rule 40 state new enable
set firewall name WAN_LOCAL rule 40 state related disable

Romo

Thanks for responding @jared

@jaredbusch said in EdgeRouter L2TP VPN can't pass IKE phase 1:

This is a working configuration I use on many routers.

L2TP config:

set vpn l2tp remote-access authentication local-users username SomeUsername password 'SomeUserPassword'
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access client-ip-pool start 10.254.203.2
set vpn l2tp remote-access client-ip-pool stop 10.254.203.10
set vpn l2tp remote-access dhcp-interface eth0
set vpn l2tp remote-access dns-servers server-1 1.1.1.1
set vpn l2tp remote-access dns-servers server-2 8.8.8.8
set vpn l2tp remote-access idle 1800
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret SomeGoodPSK
set vpn l2tp remote-access ipsec-settings ike-lifetime 3600
set vpn l2tp remote-access ipsec-settings lifetime 3600
set vpn l2tp remote-access mtu 1492

L2TP config is pretty much the same, I saw your other post and used it as well, I had the MTU set to 1492 before but on your other guide I believe I saw it at 1400 so currently have that.

If your WAN port is not DHCP, then you use this line instead of the dhcp-interface line above.
set vpn l2tp remote-access outside-address your.wan.IP.add

Static ip so outside address set.
outside-address XXX.XXX.XXX.33

IPSEC Config:

set vpn ipsec auto-firewall-nat-exclude enable
set vpn ipsec esp-group bnaesp compression disable
set vpn ipsec esp-group bnaesp lifetime 3600
set vpn ipsec esp-group bnaesp mode tunnel
set vpn ipsec esp-group bnaesp pfs enable
set vpn ipsec esp-group bnaesp proposal 1 encryption aes256
set vpn ipsec esp-group bnaesp proposal 1 hash sha1
set vpn ipsec ike-group bnaike ikev2-reauth no
set vpn ipsec ike-group bnaike key-exchange ikev1
set vpn ipsec ike-group bnaike lifetime 28800
set vpn ipsec ike-group bnaike proposal 1 dh-group 19
set vpn ipsec ike-group bnaike proposal 1 encryption aes256
set vpn ipsec ike-group bnaike proposal 1 hash sha1
set vpn ipsec ipsec-interfaces interface eth0
<snip about 8 tunnels>

IPSEC config the only thing different is I have the DH group set as 14

What seems strange is I can't even get swanctl to show me a connection attempt to see what could be wrong. This appears as if somehow I would be blocking the connection.

taurex

@jaredbusch Jared, I was talking about @Romo's site-to-site VPN config. He has two tunnels and I suggested to use a route based VPN instead. I also asked if @Romo was using public IPs on both ends or not. Because if he's behind CG-NAT, the current config wouldn't work.

taurex

@romo Could you show your firewall rules in the config output, please?

Romo

@taurex here it is

show firewall name WAN_LOCAL
 default-action drop
 description "WAN to router"
 rule 10 {
     action accept
     description "Allow established/related"
     state {
         established enable
         related enable
     }
 }
 rule 20 {
     action drop
     description "Drop invalid state"
     state {
         invalid enable
     }
 }
 rule 30 {
     action accept
     description "Allow iCMP"
     disable
     log disable
     protocol icmp
 }
 rule 40 {
     action accept
     description "Allow IKE for VPN"
     destination {
         port 500
     }
     log disable
     protocol udp
 }
 rule 50 {
     action accept
     description "Allow L2TP for VPN"
     destination {
         port 1701
     }
     log disable
     protocol udp
 }
 rule 60 {
     action accept
     description "Allow ESP for VPN"
     log disable
     protocol esp
 }
 rule 70 {
     action accept
     description "Allow NAT-T for VPN"
     destination {
         port 4500
     }
     log disable
     protocol udp
 }

taurex

@romo I don't see ipsec match-ipsec set in your L2TP rule.

Do you also have WAN_IN firewall rules set up?

Romo

@taurex said in EdgeRouter L2TP VPN can't pass IKE phase 1:

@romo I don't see ipsec match-ipsec set in your L2TP rule.

Do you also have WAN_IN firewall rules set up?

WAN_IN

name WAN_IN {
     default-action drop
     description "WAN to internal"
     rule 10 {
         action accept
         description "Allow established/related"
         state {
             established enable
             related enable
         }
     }
     rule 20 {
         action drop
         description "Drop invalid state"
         state {
             invalid enable
         }
     }
     rule 21 {
         action accept
         description "Web Traffic to Help Desk"
         destination {
             group {
                 address-group Helpdesk_internal
                 port-group HTTP_and_HTTPS
             }
         }
         log disable
         protocol tcp
         state {
             established enable
             invalid disable
             new enable
             related enable
         }
     }
     rule 22 {
         action accept
         description "Web Traffic to DevTestWeb"
         destination {
             group {
                 address-group DevTestWeb_internal
                 port-group HTTP_and_HTTPS
             }
         }
         log disable
         protocol tcp
         state {
             established enable
             invalid disable
             new enable
             related enable
         }
     }
     rule 23 {
         action accept
         description "Web Traffic to Demo"
         destination {
             group {
                 address-group Demo_internal
                 port-group HTTP_and_HTTPS
             }
         }
         log disable
         protocol tcp
         state {
             established enable
             invalid disable
             new enable
             related enable
         }
     }
     rule 24 {
         action accept
         description "Web Traffic to QB"
         destination {
             group {
                 address-group QB_Int
                 port-group RDP
             }
         }
         log disable
         protocol tcp
         state {
             established enable
             invalid disable
             new enable
             related enable
         }
     }
 }

Added the ipsec match-ipsec on WAN_LOCAL still nothing.

show firewall name WAN_LOCAL
 default-action drop
 description "WAN to router"
 rule 10 {
     action accept
     description "Allow established/related"
     state {
         established enable
         related enable
     }
 }
 rule 20 {
     action drop
     description "Drop invalid state"
     state {
         invalid enable
     }
 }
 rule 30 {
     action accept
     description "Allow iCMP"
     disable
     log disable
     protocol icmp
 }
 rule 40 {
     action accept
     description "Allow IKE for VPN"
     destination {
         port 500
     }
     log disable
     protocol udp
 }
 rule 50 {
     action accept
     description "Allow ESP for VPN"
     log disable
     protocol esp
 }
 rule 60 {
     action accept
     description "Allow NAT-T for VPN"
     destination {
         port 4500
     }
     log disable
     protocol udp
 }
 rule 70 {
     action accept
     description "Allow L2TP for VPN"
     destination {
         port 1701
     }
     ipsec {
         match-ipsec
     }
     log disable
     protocol udp
 }

taurex

@romo Have you defined ipsec interfaces with set vpn ipsec ipsec-interfaces interface eth[.]? I don't see it in your VPN config output. Also, If your static IP address gets issued by your ISP via PPPoE, you'll need to change the outside L2TP address to 0.0.0.0.

Romo

@taurex just added the ipsec-interfaces setting even though it is deprecated according to the documentation and still nothing :disappointed_face:

taurex

@romo Your site-to-site VPN doesn't work either, correct? Are you sure none of the routers is behind a Carrier Grade NAT (CG-NAT)? Are they all public IPs you have on both ends? L2TP doesn't work if its server is behind a NAT.

When you use a policy based VPN you need to start passing some traffic through the tunnel to bring it up. Have you tried pinging a device on the other router's network tunnelled through the VPN?

What's the output of show log | match 'xl2tpd|pppd'?

Romo

@taurex Site to site is working properly

Romo

Downgraded to 1.10.5 and still can't establish a proper connection or get any other type of log.

Version:      v1.10.5
Build ID:     5098915
Build on:     06/22/18 13:55
Copyright:    2012-2018 Ubiquiti Networks, Inc.
HW model:     EdgeRouter Lite 3-Port
HW S/N:       788A2041AA25
Uptime:       01:19:49 up 1 day,  4:46,  1 user,  load average: 0.23, 0.16, 0.14

Could this mean the device is having some sort of problem or could it be Internet Service Provider caused????

JaredBusch

I would have to go dig around my posts on the UBNT community to find all the various ways I got logs when troubleshooting L2TP 6 months ago.

Romo

What's really strange is that with the downgrade, it even returned to the original configuration the one that was properly working before and still nothing.

JaredBusch

@romo said in EdgeRouter L2TP VPN can't pass IKE phase 1:

What's really strange is that with the downgrade, it even returned to the original configuration the one that was properly working before and still nothing.

That is normal behavior. When you downgrade, it also reverts to the config.boot file that was used. Because obviously new firmware could potentially have config changes required that would not work with older firmware.

Romo

Yeah, I didn't find strange it reverted to using the old config, what seems strange is that it is not even working on a firmware version it used to work with and with a config that used to work as well.

Really thought the downgrade would have made it work again.

Romo

A DNAT rule was the culprit of everything, it was redirecting the traffic and not letting it reach WAN_LOCAL.

FINALLY SOLVED!!!!!!!!!!!!!!!!!!!!!!!!!

As reminder for anyone that could encounter a similar issue:
DNAT rules are evaluated before firewall rules.

scottalanmiller

@romo said in EdgeRouter L2TP VPN can't pass IKE phase 1:

A DNAT rule was the culprit of everything, it was redirecting the traffic and not letting it reach WAN_LOCAL.

FINALLY SOLVED!!!!!!!!!!!!!!!!!!!!!!!!!

As reminder for anyone that could encounter a similar issue:
DNAT rules are evaluated before firewall rules.

Also as a remember, don't wait a month before reporting an issue, we weren't looking at rules, as they had not changed for a month!

JaredBusch

@romo said in EdgeRouter L2TP VPN can't pass IKE phase 1:

A DNAT rule was the culprit of everything, it was redirecting the traffic and not letting it reach WAN_LOCAL.

FINALLY SOLVED!!!!!!!!!!!!!!!!!!!!!!!!!

As reminder for anyone that could encounter a similar issue:
DNAT rules are evaluated before firewall rules.

Yes, this is a known function of VyOS/EdgeOS. But nothing was ever posted baout DNAT rules in use, so I assumed there were none. There are not by default.