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Re: [lvs-users] passive ftp configuration issue

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] passive ftp configuration issue
From: Vincent Li <vincent.mc.li@xxxxxxxxx>
Date: Tue, 25 Mar 2014 12:28:26 -0700
Yes, ip_vs_ftp module is loaded properly

# lsmod | grep  nf
nf_conntrack_ipv4      16212  2
nf_defrag_ipv4          1710  1 nf_conntrack_ipv4
nf_nat                 16229  1 ip_vs_ftp
nf_conntrack_ipv6      10295  2
nf_defrag_ipv6         27851  1 nf_conntrack_ipv6
nf_conntrack           93079  5
nf_conntrack_ipv4,nf_nat,ip_vs,nf_conntrack_ipv6,xt_state
ipv6                  359467  53
bridge,ip_vs,ip6t_REJECT,nf_conntrack_ipv6,nf_defrag_ipv6,[permanent]

# lsmod | grep  ftp
ip_vs_ftp               6731  0
nf_nat                 16229  1 ip_vs_ftp
ip_vs                 157311  6 ip_vs_ftp,ip_vs_rr

it looks to me when client start the ftp data connection with SYN with
ephemeral port, the director has no idea how to handle this ftp data
connection, there is no listener 192.168.1.169:11196 on director to
handle the SYN packet, my understanding is that the iptables mangle
rule will set a firewall mark on 192.168.1.169:11196 so director knows
it should be some connection relate to vip 192.168.1.169:21 and LVS
should handle it, or I am missing something?



On Mon, Mar 24, 2014 at 11:52 PM, Malcolm Turnbull
<malcolm@xxxxxxxxxxxxxxxx> wrote:
> Vincent,
>
> In NAT mode, the
> ip_vs_ftp module is used to ensure that the client connects back via
> the load balancer rather than attempting
> to connect directly to the Real Server. Have you got the module loaded?
>
> You only need the firewall rules if you are in DR/gate mode.
>
>
>
>
>
> On 25 March 2014 04:40, Vincent Li <vincent.mc.li@xxxxxxxxx> wrote:
>> Hi,
>>
>> I am following http://www.centos.org/docs/4/html/rh-cs-en-4/s1-lvs-ftp.html
>> to set ftp virtual server,  passive ftp not working , the active ftp
>> works fine:
>>
>> -----LVS config
>>
>>
>> -A -t 192.168.1.169:21 -s rr
>> -a -t 192.168.1.169:21 -r 192.168.3.2:21 -m
>> -a -t 192.168.1.169:21 -r 192.168.3.3:21 -m
>>
>> # ipvsadm -L
>> IP Virtual Server version 1.2.1 (size=4096)
>> Prot LocalAddress:Port Scheduler Flags
>>   -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
>> TCP  192.168.1.169:ftp rr
>>   -> 192.168.3.2:ftp              Masq    1      0          0
>>   -> 192.168.3.3:ftp              Masq    1      0          0
>>
>>
>> iptables rules
>>
>> /sbin/iptables -t mangle -A PREROUTING -p tcp -d 192.168.1.169/32
>> --dport 21 -j MARK --set-mark 21
>> /sbin/iptables -t mangle -A PREROUTING -p tcp -d 192.168.1.169/32
>> --dport 10000:20000 -j MARK --set-mark 21
>>
>> -----real server vsftpd related config
>>
>> pasv_address=192.168.1.169
>> pasv_min_port=10000
>> pasv_max_port=20000
>>
>>
>> tcpdump for passive ftp data connection shows :
>>
>> 21 0.420062 192.168.1.9 192.168.1.169 TCP 74 50641 > 11196 [SYN] Seq=0
>> Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=1491521 TSecr=0 WS=32
>>
>> 25 3.425842 192.168.1.169 192.168.1.9 ICMP 102 Destination unreachable
>> (Host unreachable)
>>
>> Transmission Control Protocol, Src Port: 50641 (50641), Dst Port:
>> 11196 (11196), Seq: 4055858902
>>
>> I extracted out the tcp part of the icmp host unreachable message
>> above, as you can see, it indicates that LVS seems has no
>> listener/virtual for the client ftp data connection '50641 > 11196
>> [SYN]',  I thought the iptable mangle rules should  handle the passive
>> ftp data connection, it appears not. am I miss anything?
>>
>> I am running the latest Linux 3.14.0-rc7+, all the related
>> netfilter/ipvs ftp modules are loaded properly, netfilter/ipvs
>> connection tracking are enabled too.
>>
>> Regards,
>>
>> Vincent
>>
>> _______________________________________________
>> Please read the documentation before posting - it's available at:
>> http://www.linuxvirtualserver.org/
>>
>> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
>> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
>> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>
>
>
> --
> Regards,
>
> Malcolm Turnbull.
>
> Loadbalancer.org Ltd.
> Phone: +44 (0)870 443 8779
> http://www.loadbalancer.org/
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users

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