IPtables slowing down my proftpd server.

Discussion in 'Installation/Configuration' started by Tohubohu, Mar 15, 2007.

  1. Tohubohu

    Tohubohu New Member


    I've been working on a new linux box with proftpd server and im at the point where I need to secure the server.

    Iptables is set to block everything incoming and outgoing expect a few services like SSH INPUT, ICMP INPUT & OUTPUT, DNS OUTPUT and FTP INPUT

    Here is the rule that seem to be causing problems:

    -A INPUT -i eth0 -d -p tcp -m tcp --sport 1024:65535 --dport 21 -j ACCEPT

    If ip tables tables is off, I get a prompt for a username in less then a second. When ip tables is turned on, it takes a good 5-10 seconds.

    I also have 4 stateful rules:

    -A INPUT -i eth0 -p tcp -m state --state RELATED,ESTABLISHED -j ACCEPT
    -A INPUT -i eth0 -p udp -m state --state RELATED,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p udp -m state --state RELATED,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m state --state RELATED,ESTABLISHED -j ACCEPT

    Anyone ever encountered a smilar problem? Anyone has any idea of what can possibly be wrong in this case?

    Many thanks! :D
  2. Tohubohu

    Tohubohu New Member

    I just found the solution to my problem. I spammed netstats and packet-sniffed myself to finally see that the authentication was tried on port 113 first, then timed out and tried on port 21.

    So if anyone is having a similar problem, opening tcp port 113 in iptables worked for me. It might be a different port for other services, its just a matter of finding which one.
  3. edge

    edge Active Member Moderator

    Sorry for this late reply, but if you add IdentLookups off within the <Global></Global> option than this will also fix the "slow" login.

    I'm not 100% sure, but I used to have this problem also (with my IPtables), and doing the "IdentLookups off" fixed the problem for me.
  4. Tohubohu

    Tohubohu New Member

    Thanks a lot, I will try that with the port 113 removed port from iptables and see what happens.

    EDIT: Yep, that made it and I prefer that solution too. Thank you very much!
    Last edited: Mar 19, 2007

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