wiki:TipAndDoc/network

Version 10 (modified by mitty, 15 years ago) (diff)

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  1. disable ipv6
  2. open relay test
  3. iptables
  4. warning with dhcp3
  5. /etc/ppp/ip-up.local
  6. SYN Cookies
  7. calculate netmask

disable ipv6

  • 以下の一行を、modprobeの設定ファイルに追加 
    install ipv6 /sbin/modprobe -n -i ipv6
    • Ubuntu -> /etc/modprobe.d/blacklist (/etc/modprobe.d/* のどれでも可)
    • RedHat -> /etc/modprobe.conf

open relay test

  • telnet localhost 25 「以外」のIPで繋いで、以下のような例でメール送信できたらOpen relayになっているので注意 
    HELO mitty.jp
MAIL FROM: hoge@mitty.jp
RCPT TO: fuga@example.org
DATA
From: hoge@mitty.jp
Subject: test
relay testmail
.
QUIT

iptables

warning with dhcp3

/etc/ppp/ip-up.local

SYN Cookies

  • to enable
    • sysctl -w net.ipv4.tcp_syncookies=1
    • /etc/sysctl.conf > net.ipv4.tcp_syncookies=1

calculate netmask

  • ipcount <= perlのNet::IPモジュールに含まれる
    • aptitude install libnet-ip-perl
      • /usr/share/doc/libnet-ip-perl/examples/ipcount 
        Usage:
        ipcount [-r] [-d <prefix>] address

        -r: Print Reverse Ranges
        -d <prefix>: Cut down the original prefix in several prefixes

The address range can be one of:

ipcount IP + size
ipcount IP1 - IP2
ipcount IP/len
  • via ​tool/netmask計算 - Linux Tips

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