Quick IPFW Question Concerning Sendmail

[Sereciya Kurdistani]

Earlier...
       
> > Hello,
> >
> >   I have a quick question for you ipfw/firewall experts out there.
> >
> >   I've have set up an elaborate firewall only to have trouble with
> >   Sendmail.
> >
> >   I have opened port 25 incoming, and also allow outgoing to another
> >   port 25, but I always find stuck mail when I use "mailq".
> >
> >   Using tcpdump -- and no firewall -- I've found that between the
> >   dns lookups and smtp connections there are in fact some auth
> >   lookups too.
> >
> >   I opened incoming port 113 and outgoing to 113 but I still have
> >   stuck mail!
> >
> >   Any help would be greately appreciated, many thanks in advance!
> >
> > -Sereciya Kurdistani
> >
> > PS
> > My basic rules look like:
> >
> > ipfw add NNNN allow \{ tcp or udp \}     from any to any smtp,smtps out
> > ipfw add NNNN allow \{ tcp \}        log from any to any smtp,smtps in
> >
> > ipfw add NNNN allow \{ tcp or udp \}     from any to any auth out
> > ipfw add NNNN allow \{ tcp \}        log from any to any auth in
> >
       
  Later I found out that I had to allow connections to my high port from
  outside low ports incoming:
       
  ipfw allow tcp from any 1-1024 to any 1025-65535 in via ${oif_1}...
       
  The reason for this was that I forgot to add a "keep-state" ;))
       
  Here's my final solution:
       
  vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
  ipfw add NNNN check-state
  ipfw add NNNN allow      { udp or tcp } from any to any dst-port smtp,auth,smtps out via tun0 keep-state
  ipfw add NNNN allow  log   tcp          from any to any dst-port smtp,smtps      in  via tun0
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       
  This way, you don't have to allow any ports open for any incoming traffic not matched
  by the stateful rules, ;)

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