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Asked: 2015-04-16 11:51:22 +0800 CST

What I have to modify to have SELinux allow nginx to act as an IMAP/POP3 proxy?

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By default nginx under CentOS 7 will fail to start if used as an IMAP/POP proxy. This is because of SELinux.

How can SELinux's configuration be altered, without disabling its protections, to allow nginx to act as desired?

audit.log

type=AVC msg=audit(1429125129.833:2286): avc:  denied  { name_bind } for  pid=26451 comm="nginx" src=143 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:pop_port_t:s0 tclass=tcp_socket

nginx.conf

mail {
        auth_http                       unix:/run/nginx-mailauth.sock;
        ssl_prefer_server_ciphers       on;
        ssl_session_cache               shared:mail-TLSSL:16m;
        ssl_session_timeout             10m;
        ssl_session_tickets             on;
        ssl_certificate                 /etc/pki/tls/certs/mail.example.com.cer;
        ssl_certificate_key             /etc/pki/tls/private/mail.example.com.key;
        ssl_session_ticket_key          /etc/pki/tls/private/mail.example.com-session_ticket.key;
        ssl_protocols                   TLSv1 TLSv1.1 TLSv1.2;

        #For antimony-webmail
        imap_capabilities               "IMAP4rev1" "ACL" "BINARY" "CATENATE" "CHILDREN" "CONDSTORE" "ENABLE" "ESEARCH" "ID" "IDLE" "LIST-EXTENDED" "LITERAL+" "MULTIAPPEND" "NAMESPACE" 
        server {
                protocol        imap;
                listen          143;
                starttls        only;
        }
        server {
                protocol        imap;
                listen          993;
                ssl             on;
        }

        #For antimony-webmail
        pop3_capabilities       "EXPIRE 31 USER" "TOP" "UIDL" "USER" "XOIP";
        server {
                protocol        pop3;
                listen          110;
                starttls        only;
                pop3_auth       plain;
        }
        server {
                protocol        pop3;
                listen          995;
                ssl             on;
                pop3_auth       plain;
        }
}

systemctl

[root@mail ~]# systemctl start nginx
Job for nginx.service failed. See 'systemctl status nginx.service' and 'journalctl -xn' for details.
[root@mail ~]# systemctl status nginx.service
nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled)
   Active: failed (Result: exit-code) since Wed 2015-04-15 12:12:09 PDT; 5s ago
  Process: 26446 ExecStop=/bin/kill -s QUIT $MAINPID (code=exited, status=0/SUCCESS)
  Process: 25373 ExecReload=/bin/kill -s HUP $MAINPID (code=exited, status=0/SUCCESS)
  Process: 26400 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 26451 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=1/FAILURE)
 Main PID: 26402 (code=exited, status=0/SUCCESS)

Apr 15 12:12:09 mail.dev.example.com nginx[26451]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Apr 15 12:12:09 mail.dev.example.com nginx[26451]: nginx: [emerg] bind() to 0.0.0.0:143 failed (13: Permission denied)
Apr 15 12:12:09 mail.dev.example.com nginx[26451]: nginx: configuration file /etc/nginx/nginx.conf test failed
Apr 15 12:12:09 mail.dev.example.com systemd[1]: nginx.service: control process exited, code=exited status=1
Apr 15 12:12:09 mail.dev.example.com systemd[1]: Failed to start The nginx HTTP and reverse proxy server.
Apr 15 12:12:09 mail.dev.example.com systemd[1]: Unit nginx.service entered failed state.
nginx

1 Answers

  1. Nginx is being stopped from binding to SELinux pop_port_t ports.

    It possible is to alter the desired ports to be a type that nginx can bind to, e.g. http_port_t.

    # for port in {143,993,110,995} ; do semanage port -m -t http_port_t -p tcp $port ; done && semanage port -l -C
SELinux Port Type              Proto    Port Number
http_port_t                    tcp      143, 993, 110, 995
    • 4