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* Help on IPTABLES
@ 2003-10-09 12:20 info
  2003-10-11 14:32 ` Leonardo Rodrigues Magalhães
  0 siblings, 1 reply; 12+ messages in thread
From: info @ 2003-10-09 12:20 UTC (permalink / raw)
  To: netfilter

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hi all,

 Can somebody explain to me why is when i changed my Chain INPUT Rules 
from ACCEPT to DROP, i cannot browse the internet despite opening port 
80 in the INPUT rule.
However, when Chain INPUT is changed to ACCEPT, browsing the internet 
works fine. (Note: CHAIN Output is accept for ALL)


The configurations on my IPTABLES are as follows

_*Chain INPUT (policy DROP)*_
target     prot opt source               destination
RH-Lokkit-0-50-INPUT  all  --  anywhere             anywhere
ACCEPT     tcp  --  anywhere             anywhere           tcp spt:http
ACCEPT     udp  --  anywhere             anywhere           udp spt:http

Note that my OUTPUT Rules are as follows:

_*Chain OUTPUT (policy ACCEPT)*_
target     prot opt source               destination

I have two network cards installed on my pc - running Red Hat 9.0

Routing for static routes are follows:

xx.yy.zz.aa        0.0.0.0         255.255.255.0       U     0      
0        0 eth0
xx.0.0.0           0.0.0.0         255.0.0.0           U     0      
0        0 eth1
127.0.0.0          0.0.0.0         255.0.0.0           U     0      
0        0 lo
0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      
0        0 eth0
0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      
0        0 eth1

where zz.zz.zz.zz is my gateway to the internet.
eth0 - Interface with local address
eth1 - Interface with Internet address.

By the way, is there a way to save static routes because when i reboot 
my pc, all routes are lost.

Thanks for any help.

guy



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* Help on IPTABLES
@ 2003-10-09 12:24 Gilles Yue
  2003-10-09 13:54 ` Rob Sterenborg
  2003-10-14  6:59 ` Joel Newkirk
  0 siblings, 2 replies; 12+ messages in thread
From: Gilles Yue @ 2003-10-09 12:24 UTC (permalink / raw)
  To: netfilter

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Hi all,

Can somebody explain to me why is when i changed my Chain INPUT Rules
from ACCEPT to DROP, i cannot browse the internet despite opening port
80 in the INPUT rule.
However, when Chain INPUT is changed to ACCEPT, browsing the internet
works fine. (Note: CHAIN Output is accept for ALL)


The configurations on my IPTABLES are as follows

Chain INPUT (policy DROP)
target     prot opt source               destination
RH-Lokkit-0-50-INPUT  all  --  anywhere             anywhere
ACCEPT     tcp  --  anywhere             anywhere           tcp spt:http
ACCEPT     udp  --  anywhere             anywhere           udp spt:http

Note that my OUTPUT Rules are as follows:

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I have two network cards installed on my pc - running Red Hat 9.0

Routing for static routes are follows:

xx.yy.zz.aa        0.0.0.0         255.255.255.0       U     0      0
0 eth0
xx.0.0.0           0.0.0.0         255.0.0.0           U     0      0
0 eth1
127.0.0.0          0.0.0.0         255.0.0.0           U     0      0
0 lo
0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      0
0 eth0
0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      0
0 eth1

Where zz.zz.zz.zz is my gateway to the internet.
eth0 - Interface with local address
eth1 - Interface with Internet address.

By the way, is there a way to save static routes because when i reboot
my pc, all routes are lost.

Thanks for any help.

gilles



 

  _____  

 

 


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^ permalink raw reply	[flat|nested] 12+ messages in thread
* RE: Help on IPTABLES
@ 2003-10-10  6:43 Gilles Yue
  0 siblings, 0 replies; 12+ messages in thread
From: Gilles Yue @ 2003-10-10  6:43 UTC (permalink / raw)
  To: Rob Sterenborg, netfilter

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Hi Rob, 

 

I have made changes just like you said. And I still I cannot browse! 

Is there something wrong with my other chain rules or with the routing
with my network cards?(Note I have two network cards) Please help.
Thanks. 

 

 

Chain INPUT (policy DROP)

 

target     prot opt source               destination

 

RH-Lokkit-0-50-INPUT  all  --  0.0.0.0/0            0.0.0.0/0

ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:80

ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0          udp dpt:80

 

Chain FORWARD (policy ACCEPT)

 

target     prot opt source               destination

RH-Lokkit-0-50-INPUT  all  --  0.0.0.0/0            0.0.0.0/0

 

Chain OUTPUT (policy ACCEPT)

 

target     prot opt source               destination

 

Chain RH-Lokkit-0-50-INPUT (2 references)

target     prot opt source               destination

ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp 

dpts:0:1023 flag                                            s:0x16/0x02 

reject-with icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:2049


flags:0                                            x16/0x02 reject-with 

icmp-port-unreachable

REJECT     udp  --  0.0.0.0/0            0.0.0.0/0          udp 

dpts:0:1023 reje                                            ct-with 

icmp-port-unreachable

REJECT     udp  --  0.0.0.0/0            0.0.0.0/0          udp dpt:2049


reject-                                            with 

icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp 

dpts:6000:6009 f                                            

lags:0x16/0x02 reject-with icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:7100


flags:0                                            x16/0x02 reject-with 

icmp-port-unreachable

 

 

 

 

 

 

 

 

 

 

-----Original Message-----
From: Rob Sterenborg [mailto:rob@sterenborg.info] 
Sent: Thursday, October 09, 2003 5:55 PM
To: Gilles Yue; netfilter@lists.netfilter.org
Subject: RE: Help on IPTABLES

 

> Can somebody explain to me why is when i changed my Chain 

> INPUT Rules from ACCEPT to DROP, i cannot browse the internet 

> despite opening port 80 in the INPUT rule.

...

> Chain INPUT (policy DROP)

> target     prot opt source               destination

> RH-Lokkit-0-50-INPUT  all  --  anywhere             anywhere

> ACCEPT     tcp  --  anywhere             anywhere           

> tcp spt:http

> ACCEPT     udp  --  anywhere             anywhere           

> udp spt:http

 

Because you used sport. You are trying to reach servers that are

*listening* on port 80/443 so you should use dport (destination = port

80/443). You are most likely not sending from port 80/443.

 

 

Gr,

Rob

 


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^ permalink raw reply	[flat|nested] 12+ messages in thread
* RE: Help on IPTABLES
@ 2003-10-13 12:09 Gilles Yue
  2003-10-13 13:23 ` Ralf Spenneberg
  0 siblings, 1 reply; 12+ messages in thread
From: Gilles Yue @ 2003-10-13 12:09 UTC (permalink / raw)
  To: Leonardo Rodrigues Magalhães; +Cc: netfilter

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Dear Leonardo,

                        Thanks for your reply.

 

I've just allowed port 53/443 as well. Still cannot browse. Do u think it's got something to do with the routing of my two network cards.

 

                        When I change my INPUT chain to accept all, browsing works. (Note I am talking about browsing on the host where iptables has been installed)

 

                        Or do I have to insert a new rule to enable NAT. Below is my chain rules. Thanks for replying.

 

gilles

 

 

Chain INPUT (policy DROP)

target     prot opt source               destination

RH-Lokkit-0-50-INPUT  all  --  0.0.0.0/0            0.0.0.0/0

ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:80

ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0          udp dpt:80

ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:443

ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0          udp dpt:443

ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp spt:53

ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0          udp spt:53

 

Chain FORWARD (policy ACCEPT)

target     prot opt source               destination

RH-Lokkit-0-50-INPUT  all  --  0.0.0.0/0            0.0.0.0/0

 

Chain OUTPUT (policy ACCEPT)

target     prot opt source               destination

 

Chain RH-Lokkit-0-50-INPUT (2 references)

target     prot opt source               destination

ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp 

dpts:0:1023 flags:0x16/0x02 reject-with icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:2049 

flags:0x16/0x02 reject-with icmp-port-unreachable

REJECT     udp  --  0.0.0.0/0            0.0.0.0/0          udp 

dpts:0:1023 reject-with icmp-port-unreachable

REJECT     udp  --  0.0.0.0/0            0.0.0.0/0          udp dpt:2049 

reject-with icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp 

dpts:6000:6009 flags:0x16/0x02 reject-with icmp-port-unreachable

REJECT     tcp  --  0.0.0.0/0            0.0.0.0/0          tcp dpt:7100 

flags:0x16/0x02 reject-with icmp-port-unreachable

 

 

 

 

-----Original Message-----
From: Leonardo Rodrigues Magalhães [mailto:leolistas@solutti.com.br] 
Sent: Saturday, October 11, 2003 6:33 PM
To: info; netfilter@lists.netfilter.org
Subject: Re: Help on IPTABLES

 

 

    You'll probably browse with no problems if you use IP addresses. If you try to browse using names (www.something.com), you'll need to do a DNS request for the IP of that hostname. The request will go out with no problems, as OUTPUT is ACCEPT. But DNS reply will be blocked, as INPUT only allows port 80 traffic.

 

    For allowing web browsing ONLY, you'll have to allow AT LEAST packets with source port 53 (TCP and UDP - almost all will be UDP but TCP can be also used). Dont forget HTTPS too, which is port 443.

 

    You should also analyse the RH-Lokkit-0-50-INPUT chain. As packets are getting to this chain BEFORE reaching your rules, if something gets blocked there, it will NEVER reach YOUR rules.

 

    For static rules, you can create them on /etc/rc.d/rc.local. This file will be executed after ALL daemons got UP on the reboot process.

 

    Sincerily,

    Leonardo Rodrigues

 

	----- Original Message ----- 

	From: info <mailto:info@novelgmt.intnet.mu>  

	To: netfilter@lists.netfilter.org 

	Sent: Thursday, October 09, 2003 9:20 AM

	Subject: Help on IPTABLES

	 

	hi all,
	
	 Can somebody explain to me why is when i changed my Chain INPUT Rules from ACCEPT to DROP, i cannot browse the internet despite opening port 80 in the INPUT rule.
	However, when Chain INPUT is changed to ACCEPT, browsing the internet works fine. (Note: CHAIN Output is accept for ALL)
	
	
	The configurations on my IPTABLES are as follows
	
	Chain INPUT (policy DROP)
	target     prot opt source               destination
	RH-Lokkit-0-50-INPUT  all  --  anywhere             anywhere
	ACCEPT     tcp  --  anywhere             anywhere           tcp spt:http
	ACCEPT     udp  --  anywhere             anywhere           udp spt:http
	
	Note that my OUTPUT Rules are as follows:
	
	Chain OUTPUT (policy ACCEPT)
	target     prot opt source               destination
	
	I have two network cards installed on my pc - running Red Hat 9.0
	
	Routing for static routes are follows:
	
	xx.yy.zz.aa        0.0.0.0         255.255.255.0       U     0      0        0 eth0
	xx.0.0.0           0.0.0.0         255.0.0.0           U     0      0        0 eth1
	127.0.0.0          0.0.0.0         255.0.0.0           U     0      0        0 lo
	0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      0        0 eth0
	0.0.0.0            zz.zz.zz.zz       0.0.0.0           UG    0      0        0 eth1
	
	where zz.zz.zz.zz is my gateway to the internet.
	eth0 - Interface with local address
	eth1 - Interface with Internet address.
	
	By the way, is there a way to save static routes because when i reboot my pc, all routes are lost.
	
	Thanks for any help.
	
	guy
	
	


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^ permalink raw reply	[flat|nested] 12+ messages in thread
* Re: Help on IPTABLES
@ 2003-10-14 12:50 Gilles Yue
  0 siblings, 0 replies; 12+ messages in thread
From: Gilles Yue @ 2003-10-14 12:50 UTC (permalink / raw)
  To: Joel Newkirk; +Cc: netfilter

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Dear Joel,

Browsing is working now. I have removed all chains in output and forward
and starting with INPUT rules first. (Juat like u told me)

            

But I am now trying to check my mail on the box with iptables installed.
Note I have opened ports 25 and 110 and tried with both sport and dport.
Connection with local mail server cannot be made.  Did I miss something?

 

Sorry to bother you about those basic questions but I am VERY new to
iptables.

 

Thanks & Best Regards

gy

 

 

Chain INPUT (policy DROP 2858 packets, 315K bytes)

pkts bytes target     prot opt in     out     source               

destination

 

0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0           0.0.0.0/0
tcp spt:53

 

1   456 ACCEPT     udp  --  *      *       0.0.0.0/0            

0.0.0.0/0          udp spt:53

 

0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            

0.0.0.0/0          udp spt:80

 

33  6571 ACCEPT     tcp  --  *      *       0.0.0.0/0            

0.0.0.0/0          tcp spt:80

 

0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            

0.0.0.0/0          udp spt:443

 

0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            

0.0.0.0/0          tcp spt:443

 

0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            

0.0.0.0/0          tcp spt:110

 

0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            

0.0.0.0/0          udp spt:110

 

0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            

0.0.0.0/0          tcp spt:25

 

0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            

0.0.0.0/0          udp spt:25

 

 

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)

pkts bytes target     prot opt in     out     source               

destination

 

Chain OUTPUT (policy ACCEPT 664 packets, 67152 bytes)

pkts bytes target     prot opt in     out     source               

destination

 


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^ permalink raw reply	[flat|nested] 12+ messages in thread
* Help on Iptables
@ 2006-12-16 17:04 wlagmay
  2006-12-16 19:20 ` Pascal Hambourg
  0 siblings, 1 reply; 12+ messages in thread
From: wlagmay @ 2006-12-16 17:04 UTC (permalink / raw)
  To: netfilter



Hi all,

I just want to know How am I going to do a blocking of multiple ports on a
single line let say port 700 to 800.

Im trying this command but it is not working

iptables -A OUTPUT -p tcp -m state --state NEW -m tcp --dport 700-800 -j DROP
iptables -A OUTPUT -p tcp -m state --state NEW -m tcp --dport 700 --to 800 -j
DROP

I'm trying the above commands and its not working. Can you help me please?

Thanks,

 Wennie



^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2006-12-17 12:08 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-10-09 12:20 Help on IPTABLES info
2003-10-11 14:32 ` Leonardo Rodrigues Magalhães
2003-10-09 12:24 Gilles Yue
2003-10-09 13:54 ` Rob Sterenborg
2003-10-14  6:59 ` Joel Newkirk
2003-10-10  6:43 Gilles Yue
2003-10-13 12:09 Gilles Yue
2003-10-13 13:23 ` Ralf Spenneberg
2003-10-14 12:50 Gilles Yue
2006-12-16 17:04 Help on Iptables wlagmay
2006-12-16 19:20 ` Pascal Hambourg
2006-12-17 12:08   ` wlagmay

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