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New Member

Error Reset-O Reset-I

Hi all,

i have a strange error on my ASA5515-X and I can not understand what can be.

I natted server-mail with services https:

object network Owa_10.0.1.4


object network Owa_10.0.1.4

    nat (INSIDE,OUTSIDE) static interface service tcp https https

access-list INSIDE_access_in extended permit ip any any

access-list OUTSIDE_access_in extended permit ip any any

access-group INSIDE_access_in in interface INSIDE

access-group OUTSIDE_access_in in interface OUTSIDE

interface GigabitEthernet0/0

nameif INSIDE

security-level 100

ip address


interface GigabitEthernet0/1

nameif OUTSIDE

security-level 0

ip address


If i send a mail from inside to outside mail reaches the receiver, if mail is sent from outside (such as from to internal mailbox) mail does not arrive. Attached there are logs with TCP Reset-O.

what could be the issue? I have something wrong in the configuration?

Thanks in advance.


Everyone's tags (3)
New Member

Error Reset-O Reset-I

Hello Marco,

Your configuration looks all right, I would say "permit ip any any"

is okay on this case for troubleshooting purposes but do not remember later change rules on outside and only  allow services you  need to. Besides your configuration is fine. Also in log provided connection looks okay from firewall perspective.

Here is meaning of Reset-O and Reset-I according title on this post:

- TCP Reset-I - The client tear down the connection (typical in an SMTP or IMAP exchange -I = inside interface).

- TCP Reset-O - The server was not listening on that protocol at that time (usually seen as coming from SMTP servers -O = Outside interface).

I would suggest you to check if server is listening on ports required (netstat works on this), run some captures on your server maybe using wireshark in order to confirm if server is resetting connection and check out for incoming traffic.

Run  some captures on the firewall in order to confirm the reset is comming from Outside.

capture inside interface inside match tcp any host eq 443

capture outside interface outside match tcp  any host  eq 443

capture asp type asp all  >>> in order to check packets firewall has dropped.

show capture asp | inc

show capture asp  | inc

show capture inside >>>> check for tcp reset flag (R)



New Member

Error Reset-O Reset-I

Hi Jhn,

thanks a lot for reply.

Sure my acl any\any is only for this stage of troubleshhoting :-)

Later i will check on server mail with "netstat" commant for listening ports.

I take this opportunity to ask you: if i nat service https server mail on same ip address of outside interface of firewall, and if i setup a vpn anyconnect it may not work right? (overlaps https anyconnect\server mail)

Paste configuration of Anyconnect Vpn:

interface GigabitEthernet0/1

nameif OUTSIDE

security-level 0

ip address

crypto ikev2 enable OUTSIDE

crypto ikev2 remote-access trustpoint ASDM_TrustPoint0


enable OUTSIDE


anyconnect image disk0:/anyconnect-win-3.1.04072-k9.pkg 1

anyconnect profiles VpnAnyConnect_client_profile disk0:/VpnAnyConnect_client_profile.xml

anyconnect enable

tunnel-group-list enable

group-policy GroupPolicy_VpnAnyConnect internal

group-policy GroupPolicy_VpnAnyConnect attributes

wins-server none

dns-server value

vpn-tunnel-protocol ikev2

split-tunnel-policy tunnelspecified

split-tunnel-network-list value Reti_Interne

default-domain value bdossf.local


  anyconnect profiles value VpnAnyConnect_client_profile type user

tunnel-group VpnAnyConnect type remote-access

tunnel-group VpnAnyConnect general-attributes

address-pool PoolVpnAnyConnect

authentication-server-group RADIUS

default-group-policy GroupPolicy_VpnAnyConnect

tunnel-group VpnAnyConnect webvpn-attributes

group-alias VpnAnyConnect enable


I should change port of AnyConnect? or do anything else?



New Member

Re: Error Reset-O Reset-I

Hi Jhn,

i attached output of command "netstat" of server mail.

Let me know if you can.



Re: Error Reset-O Reset-I


Yes, the Anyconnect will use port 443 (this is used as it will be open on almost any location) but if you want to forward traffc to a internal webserver while having this configuration then you are in troubles.

Proposed Configuration

config te


no enable outside

port 442

enable outside


write mem

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Julio Carvajal Segura

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