重启 VPS 后，我最近设置的电子邮件服务器无法正常工作。具体来说，它无法接受端口 25 上的连接。重启之前可以。我尝试了几种方法，但不确定哪里出了问题。我希望问题很简单，但我担心可能是 SystemD、FirewallD 和 OpenVZ（使用的虚拟化类型）之间不兼容*。
需要澄清的是，在重启之前，我能够使用 telnet 向我的服务器发送邮件。我还能够从我的 gmail 帐户向服务器发送邮件/从服务器接收邮件。
我希望有人能帮助我诊断这个问题。
我认为问题出在防火墙上。以下是从 VPS 到其自身的成功 telnet 连接：
[root@VPS ~]# telnet mydomain.com 25
Trying <Server IP>...
Connected to mydomain.com.
Escape character is '^]'.
220 mail.mydomain.com ESMTP Exim 4.84_2 Mon, 13 Jun 2016 00:38:39 -0400
> HELO test
250 mail.mydomain.com Hello mydomain.com [Server IP]
> QUIT
221 mail.mydomain.com closing connection
Connection closed by foreign host.
从其他机器尝试连接时失败。请注意，域名确实解析了，这是我用来连接ssh到 VPS的 Windows 机器。ssh [email protected]
C:\Users\Liam>telnet mydomain.com 25
Connecting To mydomain.com...Could not open connection to the host, on port 25: Connect failed
以下是防火墙区域信息：
[root@VPS ~]# firewall-cmd --zone=public --list-all
public (default)
interfaces:
sources:
services: dhcpv6-client imaps pop3s smtp ssh
ports: 25/udp 587/udp 80/tcp 465/udp 465/tcp 25/tcp 587/tcp 9418/tcp 53/tcp 53/udp
masquerade: no
forward-ports:
icmp-blocks:
rich rules:
以下是 FirewallD 的当前状态
[root@VPS~]# systemctl status firewalld
* firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2016-06-12 23:14:35 EDT; 1h 30min ago
Main PID: 941 (firewalld)
CGroup: /system.slice/firewalld.service
`-941 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid
Jun 12 23:14:34 hostname systemd[1]: Starting firewalld - dynamic firewall daemon...
Jun 12 23:14:35 hostname systemd[1]: Started firewalld - dynamic firewall daemon.
Jun 12 23:14:35 hostname firewalld[941]: 2016-06-12 23:14:35 ERROR: ebtables not usable, disabling ethernet bridge firewall.
我不确定重启之前是否存在该错误，但是*这个帖子有一些关于错误以及 FirewallD + OpenVZ 的相关信息。
以下是 exim 和 dovecot 的状态，以及命名。
[root@VPS~]# systemctl status {exim,dovecot,named}
* exim.service - Exim Mail Transport Agent
Loaded: loaded (/usr
* List item
/lib/systemd/system/exim.service; enabled; vendor preset: disabled)
Active: active (running) since Sun 2016-06-12 22:08:27 EDT; 2h 38min ago
Main PID: 172 (exim)
CGroup: /system.slice/exim.service
`-172 /usr/sbin/exim -bd -q1h
Jun 12 22:08:27 hostname systemd[1]: Starting Exim Mail Transport Agent...
Jun 12 22:08:27 hostname systemd[1]: Started Exim Mail Transport Agent.
* dovecot.service - Dovecot IMAP/POP3 email server
Loaded: loaded (/usr/lib/systemd/system/dovecot.service; enabled; vendor preset: disabled)
Active: active (running) since Sun 2016-06-12 22:08:27 EDT; 2h 38min ago
Main PID: 182 (dovecot)
CGroup: /system.slice/dovecot.service
|-182 /usr/sbin/dovecot -F
|-205 dovecot/anvil
|-206 dovecot/log
|-866 dovecot/auth
`-869 dovecot/ssl-params
Jun 12 22:08:27 hostname systemd[1]: Starting Dovecot IMAP/POP3 email server...
Jun 12 22:08:27 hostname systemd[1]: Started Dovecot IMAP/POP3 email server.
* named.service - Berkeley Internet Name Domain (DNS)
Loaded: loaded (/usr/lib/systemd/system/named.service; enabled; vendor preset: disabled)
Active: active (running) since Sun 2016-06-12 22:08:27 EDT; 2h 38min ago
Main PID: 191 (named)
CGroup: /system.slice/named.service
`-191 /usr/sbin/named -u named
Jun 12 22:08:27 hostname named[191]: zone 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa/IN: loaded serial 0
Jun 12 22:08:27 hostname named[191]: zone localhost.localdomain/IN: loaded serial 0
Jun 12 22:08:27 hostname 967277 named[191]: zone localhost/IN: loaded serial 0
Jun 12 22:08:27 hostname named[191]: zone mydomain.com/IN: loaded serial 0
Jun 12 22:08:27 hostname named[191]: all zones loaded
Jun 12 22:08:27 hostname systemd[1]: Started Berkeley Internet Name Domain (DNS).
Jun 12 22:08:27 hostname named[191]: running
Jun 12 22:08:27 hostname named[191]: zone domain.com/IN: sending notifies (serial 0)
Jun 12 22:15:21 hostname systemd[1]: Started Berkeley Internet Name Domain (DNS).
Jun 12 23:08:27 hostname named[191]: listening on IPv4 interface venet0:0, <VPS IP>#53
摘自我的exim.conf文件：
[root@VPS~]# cat /etc/exim/exim.conf | grep daemon_smtp
daemon_smtp_ports = 25 : 465 : 587
而且，我不确定这是否相关，但这里有一些iptables信息。
[root@VPS~]# iptables -L | grep smtp
ACCEPT tcp -- anywhere anywhere tcp dpt:smtp ctstate NEW
ACCEPT udp -- anywhere anywhere udp dpt:smtp ctstate NEW
ACCEPT tcp -- anywhere anywhere tcp dpt:smtp ctstate NEW
[root@VPS~]# iptables -L -n | grep 25
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:25 ctstate NEW
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:25 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:25 ctstate NEW
我很乐意提供更多可能相关的信息。另外，这是我在网站上的第一篇帖子。我认为这是主题，但我也简要讨论了 Unix 或 Superuser。
更新
我关闭了防火墙：
[root@domain~]# systemctl stop firewalld
[root@domain~]# systemctl status firewalld
* firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Mon 2016-06-13 01:52:47 EDT; 4s ago
Process: 941 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
Main PID: 941 (code=exited, status=0/SUCCESS)
Jun 12 23:14:34 hostname systemd[1]: Starting firewalld - dynamic fire....
Jun 12 23:14:35 hostname systemd[1]: Started firewalld - dynamic firew....
Jun 12 23:14:35 hostname firewalld[941]: 2016-06-12 23:14:35 ERROR: eb....
Jun 13 01:52:47 hostname systemd[1]: Stopping firewalld - dynamic fire....
Jun 13 01:52:47 hostname systemd[1]: Stopped firewalld - dynamic firew....
Hint: Some lines were ellipsized, use -l to show in full.
然后我检查了iptables服务
[root@domain~]# systemctl status iptables
* iptables.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
[root@domain~]# service iptables status
Redirecting to /bin/systemctl status iptables.service
* iptables.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
当我尝试通过 25 端口 telnet 到 VPS 时仍然出现同样的错误。
答案1
问题可能出在您的机器之外。您可以尝试远程登录您的 ISP SMTP 服务器或 Gmail 服务器，以测试它是否正常工作。
有些 ISP 会阻止 SMTP 连接，以阻止病毒从非托管计算机传播。对于这种情况，您可以要求 ISP 打开从您的计算机到服务器的连接。