DIVER OSINT CTFでメール送信を設定した

FROM ubuntu:24.04

# postfixをインストールする為に、パッケージを更新
RUN apt update && apt upgrade -y

# postfixをインストール
RUN DEBIAN_FRONTEND=noninteractive apt install postfix -y
RUN apt install libsasl2-modules -y

# コンテナ起動時のスクリプト
COPY ./entrypoint.sh /
ENTRYPOINT ["/entrypoint.sh"]

#!/bin/bash

# postfixの起動
postfix start

# Postfixは/var/spool/postfixにchrootするので、
# 名前解決に際して、/etc/resolv.confではなく/var/spool/postfix/etc/resolv.confを見に行く。
# 従って、/etc/resolv.confをコピーする。
cp /etc/resolv.conf /var/spool/postfix/etc/resolv.conf

# SASL認証用のテーブル作成
chown root:root /etc/postfix/sasl_passwd
postmap /etc/postfix/sasl_passwd

# postfixの設定変更を反映させる
postfix reload

# コンテナの起動を維持するため
tail -f /dev/null

$ docker build -t postfix-with-sasl .
$ docker images
REPOSITORY                   TAG       IMAGE ID       CREATED       SIZE
postfix-with-sasl   latest    e5d80896a6b3   2 min ago   213MB

  postfix:
    # 自分でイメージをビルドした場合は`postfix-with-sasl:latest`に設定
    image: ychandev/postfix-with-sasl:latest
    restart: always
    volumes:
      - ./conf/postfix/main.cf:/etc/postfix/main.cf
      - ./conf/postfix/sasl_passwd:/etc/postfix/sasl_passwd
    depends_on:
      - ctfd
    networks:
        default:
        internal:

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 3.6 on
# fresh installs.
compatibility_level = 3.6

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level=may

smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level=may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = localhost.lan
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = $myhostname, localhost, localhost.localdomain, , localhost
# 他のコンテナからのアクセスを許可する
mynetworks_style = subnet
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
# ipv6が解決できないことがあるのでipv4のみを使用する
inet_protocols = ipv4

# ログファイルの設定
maillog_file = /var/log/mail.log

relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_sasl_mechanism_filter = plain
smtp_use_tls = yes

[smtp.gmail.com]:587 [email protected]:aaaabbbbccccdddd

$ docker compose up -d