我知道已经有一个帖子提到如何只允许 postfix 通过端口 25 发送邮件。 防火墙规则仅允许 Postfix 通过端口 25 上的 SMTP 发送电子邮件
我的问题是，如果我指定链接线程中提到的 iptables 规则，我就无法再发送电子邮件。
iptables -I OUTPUT -m owner ! --uid-owner postfix -m tcp -p tcp --dport 25 -j REJECT --reject-with icmp-admin-prohibited
ip6tables -I OUTPUT -m owner ! --uid-owner postfix -m tcp -p tcp --dport 25 -j REJECT --reject-with icmp6-adm-prohibited
但是，如果我指定root它，--uid-owner它又可以工作了。因此，我通过以下方式查找了 Postfix 在哪个用户下运行ps aux | grep postfix：
postfix 8508 0.0 0.0 67476 4524 ? S 13:35 0:00 pickup -l -t fifo -u -c
postfix 13069 0.0 0.0 67472 4404 ? S 14:47 0:00 anvil -l -t unix -u -c
postfix 13266 0.0 0.0 105164 10444 ? S 14:55 0:00 smtpd -n smtp -t inet -u -c -o stress= -s 2
postfix 13267 0.0 0.0 67476 4452 ? S 14:55 0:00 proxymap -t unix -u
postfix 13274 0.0 0.0 35584 4200 ? S 14:55 0:00 plesk_saslauthd -l -t unix -u -c status=5 listen=6 dbpath=/plesk/passwd.db
root 13335 0.0 0.0 16976 988 pts/0 S+ 14:55 0:00 grep --color=auto postfix
root 14608 0.0 0.0 65408 4564 ? Ss Apr19 0:17 /usr/lib/postfix/sbin/master
postfix 25855 0.0 0.0 67648 4640 ? S 10:17 0:01 qmgr -l -t fifo -u
postfix 25908 0.0 0.0 80836 6772 ? S 10:18 0:00 tlsmgr -l -t unix -u -c
postfix 26156 0.0 0.0 398972 3484 ? Ssl Apr18 0:05 /usr/lib/plesk-9.0/psa-pc-remote -p inet:[email protected] -t 7210 -P /run/psa-pc-remote.pid -u postfix -g popuser -n
我知道 postfix 有一个主进程，需要以 运行，root否则就无法绑定到端口 25。但是，我认为 postfix 确实会在 user 下生成子进程postfix来实际发送电子邮件（通过 smtp）。您知道为什么 iptables 规则不起作用吗？用户postfix不发送电子邮件吗（它们是通过 user 发送的吗root）？我在这里遗漏了什么？
编辑：postfix 配置 -主配置文件
# 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
# TLS parameters
smtpd_tls_cert_file = /etc/postfix/postfix.pem
smtpd_tls_key_file = $smtpd_tls_cert_file
smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = zeus.lotsearch.de
alias_maps = hash:/etc/aliases, hash:/var/spool/postfix/plesk/aliases
alias_database = hash:/etc/aliases
#myorigin = /etc/mailname
mydestination = localhost.lotsearch.de, localhost, localhost.localdomain
relayhost =
mynetworks = , 127.0.0.0/8, [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
mailman_destination_recipient_limit = 1
virtual_mailbox_domains = $virtual_mailbox_maps, hash:/var/spool/postfix/plesk/virtual_domains
virtual_alias_maps = $virtual_maps, hash:/var/spool/postfix/plesk/virtual
virtual_mailbox_maps = , hash:/var/spool/postfix/plesk/vmailbox
transport_maps = , hash:/var/spool/postfix/plesk/transport
smtpd_tls_security_level = may
smtp_tls_security_level = may
smtp_use_tls = no
smtpd_timeout = 3600s
smtpd_proxy_timeout = 3600s
disable_vrfy_command = yes
smtpd_sender_restrictions = check_sender_access hash:/var/spool/postfix/plesk/blacklists, permit_sasl_authenticated
smtpd_client_restrictions = permit_mynetworks, permit_sasl_authenticated
smtp_send_xforward_command = yes
smtpd_authorized_xforward_hosts = 127.0.0.0/8 [::1]/128
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
virtual_mailbox_base = /var/qmail/mailnames
virtual_uid_maps = static:30
virtual_gid_maps = static:31
smtpd_milters = , inet:127.0.0.1:12768
sender_dependent_default_transport_maps = hash:/var/spool/postfix/plesk/sdd_transport_maps
virtual_transport = plesk_virtual
plesk_virtual_destination_recipient_limit = 1
virtual_mailbox_limit = 0
smtpd_tls_ciphers = medium
smtpd_tls_mandatory_ciphers = medium
tls_medium_cipherlist = HIGH:!aNULL:!MD5
smtpd_tls_mandatory_protocols = TLSv1 TLSv1.1 TLSv1.2
smtpd_tls_protocols = TLSv1 TLSv1.1 TLSv1.2
message_size_limit = 0
主配置文件
#
# Postfix master process configuration file. For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (no) (never) (100)
# ==========================================================================
smtp inet n - y - - smtpd
#smtp inet n - y - 1 postscreen
#smtpd pass - - y - - smtpd
#dnsblog unix - - y - 0 dnsblog
#tlsproxy unix - - y - 0 tlsproxy
#submission inet n - y - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#smtps inet n - y - - smtpd
# -o syslog_name=postfix/smtps
# -o smtpd_tls_wrappermode=yes
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#628 inet n - y - - qmqpd
cleanup unix n - y - 0 cleanup
#qmgr unix n - n 300 1 oqmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent. See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
# mailbox_transport = lmtp:inet:localhost
# virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
ifmail unix - n n - - pipe
flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe
flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe
flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe flags=R user=list:list argv=/usr/lib/plesk-9.0/postfix-mailman ${nexthop} ${user} ${recipient}
plesk_virtual unix - n n - - pipe flags=DORhu user=popuser:popuser argv=/usr/lib/plesk-9.0/postfix-local -f ${sender} -d ${recipient} -p /var/qmail/mailnames
pickup fifo n - - 60 1 pickup
qmgr fifo n - n 1 1 qmgr
smtps inet n - - - - smtpd -o smtpd_tls_wrappermode=yes
plesk_saslauthd unix y y y - 1 plesk_saslauthd status=5 listen=6 dbpath=/plesk/passwd.db
plesk-94.130.34.42-2a01-4f8-10b-1f55--2 unix - n n - - smtp -o smtp_bind_address=94.130.34.42 -o smtp_bind_address6=2a01:4f8:10b:1f55::2 -o smtp_address_preference=ipv4
plesk-94.130.34.42- unix - n n - - smtp -o smtp_bind_address=94.130.34.42 -o smtp_bind_address6= -o smtp_address_preference=ipv4
submission inet n - - - - smtpd -o smtpd_enforce_tls=yes -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_client_restrictions=permit_sasl_authenticated,reject -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination
答案1
规则：
iptables -A OUTPUT -m owner --gid-owner postfix -p tcp -m tcp --dport 25 -j ACCEPT
iptables -A OUTPUT -m owner --uid-owner root -p tcp -m tcp --dport 25 -j ACCEPT
iptables -A OUTPUT -p tcp -m tcp --dport 25 -j REJECT --reject-with icmp-port-unreachable
仅允许 postfix 和 root 用户发送电子邮件。如果有人拥有 root 访问权限，游戏就结束了。而且我们不会以 root 身份运行服务，对吗？
答案2
您似乎正在通过运行的 smtp 客户端发送外发邮件unpriv=n，该客户端是 postfix master.cf 语言该服务以 root 身份运行。您发布的配置并不能证明这一点 - 但我的猜测是，这就是您的传输图配置所使用的。
name type private unpriv chroot wakeup maxproc command
plesk-.. unix - n n - - smtp -o ..
你需要做的是：仔细检查是谁以及为什么添加了这一行（名字普莱斯克看起来像一个提示），服务的哪一部分实际上需要 root 权限，然后将这些任务与 smtp 客户端分开。经验法则：发送邮件通常不是一项需要很多特殊权限的任务。以 root 身份运行 smtp 客户端通常是疯狂的。
您的 smtp 客户端的 root 权限可能完全没有必要，因此您只需将服务从 更改为unpriv=n即可unpriv=y。
我强烈建议您摆脱 Plesk 后，从您最喜欢的发行版的一组全新配置开始，仅添加您需要的修改。Plesk 因进行配置更改而臭名昭著，这些更改在 Plesk 范围之外很难得到保护和维护，如果可能的话，您应该编写自己的配置，而不是复制 Plesk 的配置。
答案3
我认为这是因为您需要为邮件流量设置 INPUT 规则。这也适用于 GitLab 的 postfix。
iptables -A OUTPUT -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -m multiport --sport 25,110,143 -m state --state NEW,ESTABLISHED -j ACCEPT
您可能需要其他传出规则，但我发现邮件服务器在端口 25 上发送时似乎会 ping 回服务器。
您不必使用多端口，它只是作为示例。如果您只想在该规则上使用 25 个端口，则它将如下所示：
iptables -A INPUT -p tcp --sport 25 -m state --state NEW,ESTABLISHED -j ACCEPT