Forum Discussion
PInkFloyd
Nimbostratus
NimbostratusPassive FTP using FTP profile
Hi Community,
I have an F5 Big-IP 16.0.1.1 running on AWS with a FTP server behind running vsftpd.
The idea is balance passive ftp publically. So, clients should hit public IP of the F5 for passive ftp. This scenario is running perfectly without an FTP profile, just a tcp profile (all ports) and the option pasv_address on the ftp server pointing to the public IP address of the F5. But I need to have this working with the FTP profile in order to implement extra security for FTP on the F5.
I've tried to implement FTP passive load balancing using official documentations like (https://techdocs.f5.com/en-us/bigip-15-0-0/big-ip-local-traffic-manager-implementations/load-balancing-passive-mode-ftp-traffic.html ) , but no matter what combination or configuration is implemented on the F5 & the ftp server, if I have the ftp profile the message ("passive mode refused") is always received after request PASV and only works if I use this for internal passive ftp, meaning that I not configure a "pasv_address" on the ftp server, and the client that request the connection is in the same Lan than the F5 & ftp server, resolving everything internally.
As a said, i've tried a lot of combinations and settings on the F5 and ftp servers, but nothing works. Could someone give me a little of guidance here?
Thanks in advance.
richard_polyakAltocumulus
Daniel - I have had issues setting up FTP virtual servers on F5 versions. My solution is the following:
ltm profile ftp prof_ftp_mydefault {
app-service none
defaults-from ftp
inherit-parent-profile enabled. <--------- Enabling this allowed the VS to use passive FTP.Thx
Rich
- kimbn
It's just my personal opinion right here but as for me, I strongly believe that you need to get more information about this free secure ftp server because it seems to me that you won't face this problem using that one there. If you still have any issues, you can read more reviews on the Internet as well.
- Daniel_Wolf
MVP
Did you add the iRule from my example too?
Do you really have destination address set to any?
I would compare my lab config again later today, to see if I did any further "magic" on the vsftp, or maybe I have a setting in my FTP Client that is important... I set that up 3 years ago and never touched it ever since, except of installing Linux updates.
- Daniel_Wolf
I checked this further and I cannot find any difference. I checked if I missed something in my vsftpd.conf... nope.
Your VS config seems OK, too. Can you check for the destination 0.0.0.0:0 (any) and the iRule? That seems off....
In my Wireshark capture it looks like this:
vsftp server ----> floating self-IP >> ftp.passive.ip==<IP address of the vsftp server> virtual server ----> client >> ftp.passive.ip==<IP address of the F5 virtual>So the value for ftp.passive.ip get's updated and replaced properly.
I tried with FileZilla and WinSCP, no special config required there either. Just works.
- PInkFloyd
you are right, Nat is done outside Big-ip at AWS level.
i've found an IRULE here in the forum that is used to preserve the ephemeral ports on passive FTP ( https://clouddocs.f5.com/api/irules/Passive-FTP-Preserve-Pool-Member-Ephemeral-Port.html ) and I changed it to always send the Public IP address assigned to the F5 By aws, doing this the client receives the correct IP to connect, bypassing whatever translation that ftp profile tries to make.
Anyway, it doesnt work, the client receives "227 connection to {{aws public ip. ephemeral ports}} (i've checked that the ftp server really sent those) , but the connection died there....
I'm really stuck with this, I will keep you posted if i found something, but i'm not seeing another option that contacts F5 and check if they have a workaround for this.
- Daniel_Wolf
Can you share your config? This works for me out of the box.
I am using the default FTP profile.
root@(ffive01)(cfg-sync Standalone)(Active)(/Common)(tmos)# list ltm profile ftp ftp ltm profile ftp ftp { app-service none }I have a virtual listening on port 21 and the following iRule attached.
when SERVER_CONNECTED { FTP::port 40000 40200 }And this is my vsftpd.conf
listen=NO listen_ipv6=YES xferlog_enable=YES secure_chroot_dir=/var/run/vsftpd/empty anonymous_enable=NO local_enable=YES write_enable=YES chroot_local_user=YES user_sub_token=$USER local_root=/home/$USER/ftp pasv_min_port=40000 pasv_max_port=40200 userlist_enable=YES userlist_file=/etc/vsftpd.userlist userlist_deny=NONo issues at all, see tcpdump.
- PInkFloyd
Hi Daniel,
First thanks for share this information with me.
I duplicate your configs, just to prevent missconfigurations.
Here is my config.
admin@(TESTING01)(cfg-sync Standalone)(Active)(/Common)(tmos)# list ltm profile ftp ftp ltm profile ftp ftp { app-service none }FTP config
listen=NO listen_ipv6=YES local_enable=NO anonymous_enable=YES write_enable=NO anon_root=/ftp/test xferlog_enable=YES dual_log_enable=YES log_ftp_protocol=YES vsftpd_log_file=/ftp/logs/vsftpd.log xferlog_file=/ftp/logs/xferlog.log pasv_min_port=40000 pasv_max_port=40200 anon_umask=022 banner_file=/etc/vsftpd/banner.txtVIP config ( config not listed below has been kept as default)
source address: any destination address: any Service Port: 21 ftp Protocol: tcp ftp profile: ftp Vlan and Tunnel traffic: all VLANs and tunnels Source Address Translation: auto map Address translation: enabled port translation: enabled Default Pool: FTP POOLI've created an FTP monitor that retrieves a file on the ftp server , attach it to the ftp pool and its working ok.
The issue start when a remote source (whitelisted to access) connects to the FTP using the F5 public ip, everything looks good until the remote source request PASV
if my ftp pool member is configured with it Public IP, the error recieved after PASV is
421 Service not available, remote server has closed connection Passive mode refused.If my FTP pool member is configured using its private IP, the client receives ( "227 Entering Passive Mode (private VIP ip , Ephemeral Port ")
obviously can not be resolved by the remote source.
I downloaded an Irule that i found in this forum, that preserve ephemeral ports and i modified it to sent (no matter what) the public IP of the F5 when pasv is requested ( keeping the ephemeral port as it is) but again "passive mode refused" )
I've tried another combinations like use "pasv_address" on the ftp server, pointing to the F5 public & private IP, but only works if I point to Public Ip Address of the F5 and remove the ftp profile from the VIP.
