question on SYN_SENT

[Chad Leigh Shire.Net LLC]

On May 11, 2012, at 4:08 PM, Chuck Swiger wrote:

> On May 11, 2012, at 2:09 PM, Chad Leigh Shire.Net LLC wrote:
>> it is my understanding that SYN_SENT is when MY SIDE sends out a request and is awaiting a reply?
> 
> That's right.
> 
>> One of the jails we run for a customer had hundreds (if not thousands) of attempts to connect from the 147. address you see below.   It was exhausting resources so that new tcp connections could not be made until some closed.
> 
> You have/had your jail opening connections to the webserver at IP 147.237.76.155, not that IP trying to connect to you.
> 
>> I added that address to a "pf" block statement to stop it but now we get a rolling connections in a "netstat -a" as show below (host. being a generic name used in place of actual host on our side).   I am wondering if this shows something on our side trying to connect out?  That is what it appears to me to be, which does not make sense.
>> 
>> 
>> tcp4       0      0 host.52562         147.237.76.155.http    SYN_SENT
>> tcp4       0      0 host.52561         147.237.76.155.http    SYN_SENT
> 
> Yes, your side is trying to connect out.
> Unless you know better, it seems reasonable to gather that it's doing a DoS attack against:

Hi Chuck!

Thanks.  I am investigating as this side should not be going out at all, but the SYN_SENT made me think it was.

Thanks
Chad

> 
> % whois 147.237.76.155
> [ ... ]
> inetnum:      147.237.0.0 - 147.237.255.255
> netname:      IL-GOVT-NET
> descr:        Israeli Government Network
> country:      IL
> admin-c:      AT979-RIPE
> tech-c:       TT441-RIPE
> status:       ASSIGNED PI
> mnt-by:       GOV-IL-DNS
> mnt-lower:    GOV-IL-DNS
> mnt-routes:   AS8867-MNT { ANY }
> mnt-routes:   AS9116-MNT { 147.237.232.0/24^24-24 }
> source:       RIPE # Filtered
> 
> person:         Admin Tehila
> address:        Israel Ministry Of Finance
> address:        1 Netanel Lorech st
> address:        Jerusalem  Israel
> phone:          +972 2 6664666
> fax-no:         +972 2 6664650
> remarks:        For ABUSE and security issues please contact
> remarks:        email: abuse at tehila.gov.il
> remarks:        or contact CERT.gov.il at report at CERT.gov.il
> nic-hdl:        AT979-RIPE
> source:         RIPE # Filtered
> 
> Regards,
> -- 
> -Chuck
>