netdev - Re: ebtables on a stick

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 1 Dec 2011 08:14:56 +0100
From:	David Lamparter <equinox@...c24.net>
To:	Greg Scott <GregScott@...rasupport.com>
Cc:	David Lamparter <equinox@...c24.net>, netdev@...r.kernel.org
Subject: Re: ebtables on a stick

On Wed, Nov 30, 2011 at 11:46:02PM -0600, Greg Scott wrote:
> Well this is frustrating.  Now my public host can communicate anywhere it wants internally but nothing outside. Maddening - the exact opposite problem I had before.  
> 
> Here is the config as it sits right now:
> 
> Public IP host (a Windows XP system placeholder for now)
> IP 1.2.115.157, default gw 1.2.115.146.

Note that since the IP should be 1.2.115.157/_32_, it doesn't make any
difference whether you use 1.2.115.146 for the defgw or 192.168.10.1,
since both are out-of-subnet.

> Firewall eth0 - 1.2.115.146/28
> Firewall eth1 - 192.168.10.1. 
> 
> /sbin/ip neigh add proxy 1.2.115.157 dev eth0
> /sbin/ip route add 1.2.115.157/32 dev eth1
> 
> As a troubleshooting step, I also put in:
> /sbin/ip addr add 1.2.115.146/28 dev eth1; so now both eth0 and eth1 have the same IP Address.  This feels ugly and I think I'll take it out because it made no difference.  

I agree, please remove.

> And the relevant iptables rules:
> 
> $IPTABLES -t nat -A POSTROUTING -s $1.2.115.157 -j ACCEPT
> $IPTABLES -t nat -A PREROUTING -d 1.2.115.157 -j ACCEPT
> 
> $IPTABLES -A FORWARD -s 1.2.115.157 -j ACCEPT

Where is the reverse rule of this? -d 1.2.115.157 -j ACCEPT

> $IPTABLES -A FORWARD -s 192.168.10.0/24 -d 1.2.115.157 -j ACCEPT
> $IPTABLES -A FORWARD -p TCP --dport 1720 -d $ADR -j allowed
> $IPTABLES -A FORWARD -p TCP -s $MGMT_IP -d $ADR -j allowed

(what's $ADR?)
[...]
> The ICMP echo reply comes back on eth0, still good.  But I never forward it over to eth1 and it dies right there.  The public host never sees the reply. 

Firewall rules?


-David
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html