myrules comment

[Jason Opperisano]

On Wed, 2005-02-02 at 23:58, varun_saa at vsnl.net wrote:
> Hello,
>      My server is Mandrake 10.1
> eth0 is WAN with static IP connected to 512k DSL
> eth1 is LAN.
> 
> Basically I want clients to able to :
> 
> 1. send and recieve mails

internal users sending mail:

  iptables -A FORWARD -i eth1 -o eth0 -p tcp --syn \
    --sport 1024: --dport 25 -j ACCEPT

internal users receiving mail via pop3:

  iptables -A FORWARD -i eth1 -o eth0 -p tcp --syn \
    --sport 1024: --dport 110 -j ACCEPT

> 2. browse the net through squid

internal users connecting to squid:

  iptables -A INPUT -i eth1 -p tcp --syn \
    --sport 1024: --dport 3128 -j ACCEPT

squid proxy fetching content from the internet:

  iptables -A OUTPUT -p udp \
    --sport 1024: --dport 53 -j ACCEPT

  iptables -A OUTPUT -o eth0 -p tcp --syn \
    -m owner --uid-owner squid \
    --sport 1024: --dport 80 -j ACCEPT

> 3. Use MSN or Yahoo

msn:

  iptables -A FORWARD -i eth1 -o eth0 -p tcp --syn \
    --sport 1024: --dport 1863 -j ACCEPT

yahoo:

  iptables -A FORWARD -i eth1 -o eth0 -p tcp --syn \
    --sport 1024: --dport 5050 -j ACCEPT

> My iptables config is as follows :
> 
> # Generated by iptables-save v1.2.9 on Thu Oct 21 05:32:36 2004
> *nat
> :OUTPUT ACCEPT [0:0]
> :PREROUTING ACCEPT [0:0]
> :POSTROUTING ACCEPT [0:0]
> -A POSTROUTING -o eth0 -j MASQUERADE
> COMMIT
> # Completed on Thu Oct 21 05:32:36 2004
> # Generated by iptables-save v1.2.9 on Thu Oct 21 05:32:36 2004
> *mangle
> :PREROUTING ACCEPT [32056:3889577]
> :INPUT ACCEPT [32010:3885659]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [31637:4617585]
> :POSTROUTING ACCEPT [31639:4618071]
> COMMIT
> # Completed on Thu Oct 21 05:32:36 2004
> # Generated by iptables-save v1.2.9 on Thu Oct 21 05:32:36 2004
> *filter
> :FORWARD DROP [0:0]
> :INPUT DROP [0:0]
> :OUTPUT ACCEPT [0:0]
> -A INPUT -j ACCEPT

every INPUT rule after this is ignored, as you have just accepted all
packets,

> -A INPUT -s 127.0.0.1 -j ACCEPT
> -A INPUT -p tcp -m tcp -i eth1 --dport 3128 -j ACCEPT
> -A INPUT -p udp -m udp -i eth1 --dport 3128 --sport 80 -j ACCEPT
> -A INPUT -s 62.0.0.0/255.0.0.0 -i eth0 -j REJECT
> -A INPUT -p tcp -m tcp -s 217.81.0.0/255.255.0.0 -i eth0 -j REJECT
> -A INPUT -i eth0 -j DROP
> -A INPUT -p tcp -m tcp -i eth1 --sport 80 -j DROP
> -A INPUT -m state -i eth1 --state ESTABLISHED,RELATED -j ACCEPT
> -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

excellent.

> -A FORWARD -i eth1 -o eth0 -p tcp --syn --sport 1024 --dport 25 -j ACCEPT
> -A FORWARD -i eth1 -o eth0 -p tcp --syn --sport 1024 --dport 110 -j ACCEPT 

those rules will only match packets that have a source port of exactly
1024--which won't be many packets.  i think you mean "1024:"
   
-j

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