Why iptables rules does not work when used for passive FTP?

Installing and Using OpenWrt Network and Wireless Configuration
1

iptables v1.6.2 in Openwrt 18.06-SNAPSHOT. I have rules in /etc/firewall.user like this:

# This file is interpreted as shell script.
# Put your custom iptables rules here, they will
# be executed with each firewall (re-)start.

# Internal uci firewall chains are flushed and recreated on reload, so
# put custom rules into the root chains e.g. INPUT or FORWARD or into the
# special user chains, e.g. input_wan_rule or postrouting_lan_rule.

iptables -F 
iptables -X
iptables -Z


iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP


iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -p icmp -j ACCEPT
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

iptables -A INPUT -p udp --dport 15002 -j ACCEPT
iptables -A INPUT -p udp --dport 15001 -j ACCEPT
iptables -A INPUT -p udp --dport 15000 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 23 -j ACCEPT
iptables -A INPUT -p tcp --dport 9001 -j ACCEPT

iptables -A INPUT -p udp --dport 8005 -j ACCEPT
iptables -A INPUT -p udp --dport 8006 -j ACCEPT
iptables -A INPUT -p udp --dport 8011 -j ACCEPT
iptables -A INPUT -p udp --dport 7002 -j ACCEPT
iptables -A INPUT -p udp --dport 7102 -j ACCEPT
iptables -A INPUT -p udp --dport 123 -j ACCEPT
iptables -A OUTPUT -j ACCEPT

keep the file /etc/config/firewall default:

config defaults
	option syn_flood	1
	option input		ACCEPT
	option output		ACCEPT
	option forward		REJECT
# Uncomment this line to disable ipv6 rules
#	option disable_ipv6	1

config zone
	option name		lan
	list   network		'lan'
	option input		ACCEPT
	option output		ACCEPT
	option forward		ACCEPT

config zone
	option name		wan
	list   network		'wan'
	list   network		'wan6'
	option input		REJECT
	option output		ACCEPT
	option forward		REJECT
	option masq		1
	option mtu_fix		1

config forwarding
	option src		lan
	option dest		wan

# We need to accept udp packets on port 68,
# see https://dev.openwrt.org/ticket/4108
config rule
	option name		Allow-DHCP-Renew
	option src		wan
	option proto		udp
	option dest_port	68
	option target		ACCEPT
	option family		ipv4

# Allow IPv4 ping
config rule
	option name		Allow-Ping
	option src		wan
	option proto		icmp
	option icmp_type	echo-request
	option family		ipv4
	option target		ACCEPT

config rule
	option name		Allow-IGMP
	option src		wan
	option proto		igmp
	option family		ipv4
	option target		ACCEPT

# Allow DHCPv6 replies
# see https://dev.openwrt.org/ticket/10381
config rule
	option name		Allow-DHCPv6
	option src		wan
	option proto		udp
	option src_ip		fc00::/6
	option dest_ip		fc00::/6
	option dest_port	546
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-MLD
	option src		wan
	option proto		icmp
	option src_ip		fe80::/10
	list icmp_type		'130/0'
	list icmp_type		'131/0'
	list icmp_type		'132/0'
	list icmp_type		'143/0'
	option family		ipv6
	option target		ACCEPT

# Allow essential incoming IPv6 ICMP traffic
config rule
	option name		Allow-ICMPv6-Input
	option src		wan
	option proto	icmp
	list icmp_type		echo-request
	list icmp_type		echo-reply
	list icmp_type		destination-unreachable
	list icmp_type		packet-too-big
	list icmp_type		time-exceeded
	list icmp_type		bad-header
	list icmp_type		unknown-header-type
	list icmp_type		router-solicitation
	list icmp_type		neighbour-solicitation
	list icmp_type		router-advertisement
	list icmp_type		neighbour-advertisement
	option limit		1000/sec
	option family		ipv6
	option target		ACCEPT

# Allow essential forwarded IPv6 ICMP traffic
config rule
	option name		Allow-ICMPv6-Forward
	option src		wan
	option dest		*
	option proto		icmp
	list icmp_type		echo-request
	list icmp_type		echo-reply
	list icmp_type		destination-unreachable
	list icmp_type		packet-too-big
	list icmp_type		time-exceeded
	list icmp_type		bad-header
	list icmp_type		unknown-header-type
	option limit		1000/sec
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-IPSec-ESP
	option src		wan
	option dest		lan
	option proto		esp
	option target		ACCEPT

config rule
	option name		Allow-ISAKMP
	option src		wan
	option dest		lan
	option dest_port	500
	option proto		udp
	option target		ACCEPT

# include a file with users custom iptables rules
config include
	option path /etc/firewall.user


### EXAMPLE CONFIG SECTIONS
# do not allow a specific ip to access wan
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option dest		wan
#	option proto	tcp
#	option target	REJECT

# block a specific mac on wan
#config rule
#	option dest		wan
#	option src_mac	00:11:22:33:44:66
#	option target	REJECT

# block incoming ICMP traffic on a zone
#config rule
#	option src		lan
#	option proto	ICMP
#	option target	DROP

# port redirect port coming in on wan to lan
#config redirect
#	option src			wan
#	option src_dport	80
#	option dest			lan
#	option dest_ip		192.168.16.235
#	option dest_port	80
#	option proto		tcp

# port redirect of remapped ssh port (22001) on wan
#config redirect
#	option src		wan
#	option src_dport	22001
#	option dest		lan
#	option dest_port	22
#	option proto		tcp

### FULL CONFIG SECTIONS
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port	80
#	option dest		wan
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp
#	option target	REJECT

#config redirect
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port		1024
#	option src_dport	80
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp

when i start the firewall: /etc/init.d/firewall start ,it runs like this:

Warning: Unable to locate ipset utility, disabling ipset support
Warning: Section @zone[1] (wan) cannot resolve device of network 'wan'
Warning: Section @zone[1] (wan) cannot resolve device of network 'wan6'
 * Populating IPv4 filter table
   * Rule 'Allow-DHCP-Renew'
   * Rule 'Allow-Ping'
   * Rule 'Allow-IGMP'
   * Rule 'Allow-IPSec-ESP'
   * Rule 'Allow-ISAKMP'
   * Forward 'lan' -> 'wan'
   * Zone 'lan'
   * Zone 'wan'
Warning: iptc_commit(): No chain/target/match by that name
 * Populating IPv4 nat table
   * Zone 'lan'
   * Zone 'wan'
Warning: iptc_commit(): No chain/target/match by that name
 * Populating IPv4 mangle table
   * Zone 'lan'
   * Zone 'wan'
 * Flushing conntrack table ...
 * Set tcp_ecn to off
 * Set tcp_syncookies to on
 * Set tcp_window_scaling to on
 * Running script '/etc/firewall.user'
Warning: Cannot get interface addresses: Input/output error

check the status of firewall: iptables -nL -v

Chain INPUT (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  312 26248 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0           
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0           
  148  6627 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
 5885 1202K ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:15002
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:15001
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:15000
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:21
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:22
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:23
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:9001
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:8005
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:8006
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:8011
  295 16520 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:7002
    4  1536 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:7102
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:123

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 4592  319K ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0

but when connect the divice with passive FTP , the random port does not work.

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what did i miss? any idea? Thx

2

In your other thread, I said you should upgrade to a modern version of OpenWrt. 18.06 is unsupported.

3

thx, but the system can not upgrade at the moment :joy:

4

Why not? Is the hardware too old/limited? What is the device you are using?

5

the device has been used for control in the factory, i want to know that any problems with iptables rules above :joy:

6

Ok. You’ll have to wait for someone who remembers the nuances of 18.06 (snapshot, no less) and is willing to help you debug this. Because that version is so old and unsupported, there may or may not be many users who will be able/willing to help.

2 Likes
7

Thx. I think there is something wrong with system setting or iptables. the module -m state is not supported by iptables v1.6.2. but i cannot figure it out.