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message with show conn in pix

bma
Level 1
Level 1

Hi

Following is message with show conn in the pix525,ver 7.0. x.x.x.x is email server ip address. I don't think have 4g email send out in that time. How to understand this message? that source ip address is changed as time.

"TCP out 62.37.236.x:25 in x.x.x.x:28626 idle 0:07:05 bytes 4294967280 flags UO"

thanks

ben

8 Replies 8

palomoj
Level 1
Level 1

It's possible your mail server has sent 4GB+ of email over time. If you haven't modified the 'conn timeout' then the TCP session will terminate in 1 hour (inactivity) including the idle-time, byte count, and flags. The idle-time is probably throwing you off here.

Thanks.

Following is message from syslog:

2007-05-10 21:43:55 UTC Local0.Info 192.168.252.1 May 10 2007 14:42:18 : %PIX-6-302014: Teardown TCP connection -1810930958 for outside:62.37.236.x/25 to inside:x.x.x.x/24856 duration 0:10:32 bytes 4294967280 TCP Reset-O

It looks finish send, but sometime show up again in the log file.

Ben

What version are you running and are you running fixup for smtp or esmtp or do you have it disabled?

PIX version is 7.0(1), no fixup for smtp or esmtp running. Only inspect esmtp in the configuration.

I was referring to the same thing, I have a hard time referring to the newer inspection method. Try turning the esmtp inspection (disable fixup smtp for older OS) off.

Thanks, it's very helpful. What is risk if turn inspection off for esmtp or http?

Your SMTP server banner will be exposed and you won't be able to inspect RFC eSMTP commands. Most customers who run IIS or Exchange servers keep the inspection off anyways since in most cases causes problems with inbound and outbound email.

It seems as pointed out earlier that a inside host x.x.x.x did send a mail 4GB or more, however the connection was not a normal finish, it was torn down becuse the mail server on the outside RESET the connection. Notice the flags in the syslog-

TCP Reset-O

Regards,

Vibhor.

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