Re: my logs is flooding with snort w/ some weird message about port 53

[Ramin Alidousti <ramin () cannon eng us uu net>]

I think that your dns server (named) has been told to send
out queries with port (53). These are the responses coming
back. Take a look at "/etc/named.conf" and see if you have
such an entry:

options {
        ...
        query-source address * port 53;
        ...
};

If you comment this out then the queries sent out by your
server will be from the unprivileged ports (>1023) and sort
will not complain. Otherwise, take a look at:

misc.rules:

alert udp $EXTERNAL_NET 53 -> $HOME_NET :1023 (msg:"MISC source port 53 to <1024"; classtype:bad-unknown; sid:515; 
rev:2;)

Hope it helps,
Ramin



On Tue, Sep 04, 2001 at 02:47:19PM -0400, alexus wrote:

> hello
>
> for some reason i get a lot of traffic on my port 53, even though my
> nameserver is closed for public, can someone explain me what does that mean?
>
> Sep  4 14:44:05 box snort[11565]: [1:515:2] MISC source port 53 to <1024
> [Classification: Potentially Bad Traffic] [Priority: 2]: {UDP}
> 24.69.255.195:53 -> 66.92.98.145:53
> Sep  4 14:44:08 box snort[11565]: [1:515:2] MISC source port 53 to <1024
> [Classification: Potentially Bad Traffic] [Priority: 2]: {UDP}
> 194.67.2.114:53 -> 66.92.98.145:53
> Sep  4 14:44:08 box snort[11565]: [1:515:2] MISC source port 53 to <1024
> [Classification: Potentially Bad Traffic] [Priority: 2]: {UDP}
> 207.236.57.98:53 -> 66.92.98.145:53
> Sep  4 14:44:08 box snort[11565]: [1:515:2] MISC source port 53 to <1024
> [Classification: Potentially Bad Traffic] [Priority: 2]: {UDP}
> 207.236.57.98:53 -> 66.92.98.145:53
>
> just for example right now it's 2:45pm and since morning i already got
>
> su-2.05# grep -c "MISC source port 53" /var/log/all.log
> 9222
> su-2.05#
>
> of those entryes in my log
>
> please help
>
> if this a legit traffic which rule i can comment out so it wont show in my
> logs? and if this traffic is legit why is it shows as "potentially bad
> traffic"?
>
> thanks in advance
>
>
>
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