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Re: firewall problems
- To: yaniv almog <almog(at-nospam)techunix.technion.ac.il>
- Subject: Re: firewall problems
- From: "Nadav Har'El" <nyh(at-nospam)math.technion.ac.il>
- Date: Tue, 18 Sep 2001 23:21:20 +0300
- Cc: Linux-il(at-nospam)cs.huji.ac.il
- Hebrew-Date: 2 Tishri 5762
- In-Reply-To: <NDBBLMLBHLPPGLGDMBBHGEKNCBAA.almog@tx.technion.ac.il>; from almog@techunix.technion.ac.il on Sun, Sep 16, 2001 at 11:00:26PM +0200
- References: <NDBBLMLBHLPPGLGDMBBHGEKNCBAA.almog@tx.technion.ac.il>
- Sender: linux-il-bounce(at-nospam)cs.huji.ac.il
- User-Agent: Mutt/1.2i
On Sun, Sep 16, 2001, yaniv almog wrote about "firewall problems":
> Shalom,
>
> I have recently installed Red-Hat 7.1 at work. My computer is connected th
> the network via eth0. The problem is that my maschine no longeraccept
> telnet, ftp, or e-mail. I tried to disable the firewall: by the gnome-lokkit
Disabling the firewall (or better yet, punching holes in it for these
services) is a good start but not enough. You also have to be listening
for those services!
Redhat, since version 7.1, don't listen to services by default (this is a
good security decision, to prevent cracking of clueless administrators'
machines). You have to enable them, either by manually editing files
in /etc/xinetd.d (e.g., /etc/xinetd.d/telnet), changing "disable = yes"
to "disable = no", and finally running /etc/init.d/xinetd restart,
or, by using the graphical linuxconf utility.
Do this for telnet and ftp (if you want them open). See hosts_access(5)
for instructions on how to limit which hosts can access them, or configure
a firewall for that.
To enable incoming smtp (if that is what you mean by "accept e-mail" -
note that this is not typically necessary on a personal machine!), you
need to start it (this time not with xinetd - running it one time is done
with /etc/init.d/sendmail start but to enable it to run after every
boot, using linuxconf is the simplest choice), but that is not enough.
You also need to edit /etc/mail/sendmail.mc, comment out a line saying
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')
(the comments explain why), and restart sendmail with
m4 /etc/mail/sendmail.mc > /etc/sendmail.cf
/etc/init.d/sendmail restart
Good luck.
--
Nadav Har'El | Tuesday, Sep 18 2001, 2 Tishri 5762
nyh@math.technion.ac.il |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |Does replacing myself with a shell-script
http://nadav.harel.org.il |make me impressive or insignificant?
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