Firewall blocking outbound mails

Firewall blocking outbound mails

Post by sunin.. » Fri, 26 Jan 2001 06:17:17



Hello,

I have a sparc loaded with linux and am using ipchains to secure it. My
default input policy is deny and output policy is accept.

#I Open ssh
/sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x ssh
/sbin/ipchains -A output -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x ssh

#I open http
/sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x www

# Open Domain
/sbin/ipchains -A input -j ACCEPT -p udp -s n.n.n.n domain -d x.x.x.x

my server is x.x.x.x and nameserver is n.n.n.n, I'm hosting vitual mail
domains and am using aliases with those domains.

I tried opening port 25 outbound / inbound but no luck. I get following
in my maillog.

Jan 23 12:24:53 tommy sendmail[11269]: DAA10832:

=08:48:01, xdelay=02:11:30, mailer=esmtp, relay=mc4.law13.hotmail.com.
[64.4.49.
199], stat=Deferred: Connection timed out with mc4.law13.hotmail.com.

when I opened all ports the mail transfers ok. I don't know what local
ports to open for the mail. Any help would be appreciated.

Thanks

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Firewall blocking outbound mails

Post by Bill Hudso » Fri, 26 Jan 2001 08:18:41



> Hello,

> I have a sparc loaded with linux and am using ipchains to secure it. My
> default input policy is deny and output policy is accept.

> #I Open ssh
> /sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x ssh
> /sbin/ipchains -A output -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x ssh

> #I open http
> /sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x www

> # Open Domain
> /sbin/ipchains -A input -j ACCEPT -p udp -s n.n.n.n domain -d x.x.x.x

> my server is x.x.x.x and nameserver is n.n.n.n, I'm hosting vitual mail
> domains and am using aliases with those domains.

> I tried opening port 25 outbound / inbound but no luck. I get following
> in my maillog.

> Jan 23 12:24:53 tommy sendmail[11269]: DAA10832:

> =08:48:01, xdelay=02:11:30, mailer=esmtp, relay=mc4.law13.hotmail.com.
> [64.4.49.
> 199], stat=Deferred: Connection timed out with mc4.law13.hotmail.com.

> when I opened all ports the mail transfers ok. I don't know what local
> ports to open for the mail. Any help would be appreciated.

try adding the '-l' (logging) flag to your 'DENY/REJECT' rules.  If you
don't have a blanket DENY or REJECT rule then add one to gain the
logging capability.  Then you'll *see* which ports to open.

--
Bill Hudson

 
 
 

Firewall blocking outbound mails

Post by sunin.. » Sat, 27 Jan 2001 10:06:25


Thanks. :-)




> > Hello,

> > I have a sparc loaded with linux and am using ipchains to secure
it. My
> > default input policy is deny and output policy is accept.

> > #I Open ssh
> > /sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x ssh
> > /sbin/ipchains -A output -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x
ssh

> > #I open http
> > /sbin/ipchains -A input -j ACCEPT -p tcp -s 0.0.0.0/0 -d x.x.x.x www

> > # Open Domain
> > /sbin/ipchains -A input -j ACCEPT -p udp -s n.n.n.n domain -d
x.x.x.x

> > my server is x.x.x.x and nameserver is n.n.n.n, I'm hosting vitual
mail
> > domains and am using aliases with those domains.

> > I tried opening port 25 outbound / inbound but no luck. I get
following
> > in my maillog.

> > Jan 23 12:24:53 tommy sendmail[11269]: DAA10832:

> > =08:48:01, xdelay=02:11:30, mailer=esmtp,

relay=mc4.law13.hotmail.com.
Quote:> > [64.4.49.
> > 199], stat=Deferred: Connection timed out with

mc4.law13.hotmail.com.

Quote:

> > when I opened all ports the mail transfers ok. I don't know what
local
> > ports to open for the mail. Any help would be appreciated.

> try adding the '-l' (logging) flag to your 'DENY/REJECT' rules.  If
you
> don't have a blanket DENY or REJECT rule then add one to gain the
> logging capability.  Then you'll *see* which ports to open.

> --
> Bill Hudson

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http://www.deja.com/
 
 
 

1. using iptables to block OUTBOUND port 25?

Using linux as a gateway router, how does one do this?  I'd like to
prevent internal computers from making outbound port 25 connections,
but still allow them to the linux box on port 25.

So, I have eth0 as the outside network and eth1 as the inside
network.  Computers on the eth1 network need to be able to hit the
linux box on port 25, but those computers should NOT be allowed to go
out to the internet on port 25.  This is the only port I want to block
for now.

eth0:  public ip...5.6.7.8/255.255.252.0
eth1:  internal ips:  172.16.0.0/255.255.255.0

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