Qualsiasi tentativo di connessione a un server sulla porta 143 è bloccato dal sistema operativo. Ho verificato che non è la mia connessione; altri computer sulla rete possono vedere bene la porta. Ho replicato il problema su una rete diversa, oltre alle interfacce Ethernet e Wifi.
Sul mio MacBook, ottengo questo:
$ telnet mail.xxxx.com 143
Trying xxx.xxx.xxx.xxx...
telnet: connect to address xxx.xxx.xxx.xxx: Permission denied
telnet: Unable to connect to remote host
$ telnet mail.xxxx.com 110
Trying xxx.xxx.xxx.xxx...
Connected to mail.xxxx.com.
Escape character is '^]'.
+OK Welcome to MailEnable POP3 Server
su un altro computer sulla stessa rete:
$ telnet mail.xxxx.com 143
Trying xxx.xxx.xxx.xxx...
Connected to mail.xxxx.com.
Escape character is '^]'.
* OK IMAP4rev1 server ready at 07/28/11 19:53:15
Il problema è dovuto a molte regole ipfw estranee:
$ sudo ipfw show
00010 1166 210912 allow ip from any to any via lo*
00100 0 0 deny ip from 127.0.0.0/8 to any in
00110 0 0 deny ip from any to 127.0.0.0/8 in
00120 0 0 deny ip from 224.0.0.0/3 to any in
00130 0 0 deny tcp from any to 224.0.0.0/3 in
10010 0 0 check-state
10020 163 12011 deny ip from any to any established in
10030 0 0 deny ip from any to any frag in
20000 14 784 skipto 50000 icmp from any to any out keep-state
20010 227761 225019565 skipto 50000 tcp from any to any dst-port 80,8080 out setup keep-state
20011 7994 1700223 skipto 50000 tcp from any to any dst-port 443,8443 out setup keep-state
20020 0 0 skipto 50000 tcp from any to any dst-port 53 out setup keep-state
20020 1359 125457 skipto 50000 udp from any to any dst-port 53 out keep-state
20030 150 17801 skipto 50000 tcp from any to any dst-port 110,993 out setup keep-state
20031 0 0 skipto 50000 tcp from any to any dst-port 25,465,587 out setup keep-state
20040 501 54357 skipto 50000 tcp from any to any dst-port 22 out setup keep-state
20050 0 0 skipto 50000 tcp from any to any dst-port 21 out setup keep-state
20060 0 0 skipto 50000 tcp from any to any dst-port 123 out setup keep-state
20060 12 912 skipto 50000 udp from any to any dst-port 123 out keep-state
20070 0 0 skipto 50000 tcp from any to any dst-port 113 out setup keep-state
20070 0 0 skipto 50000 udp from any to any dst-port 113 out keep-state
20080 0 0 skipto 50000 tcp from any to any dst-port 194 out setup keep-state
20080 0 0 skipto 50000 udp from any to any dst-port 194 out keep-state
20090 0 0 skipto 50000 tcp from any to any dst-port 137-139,445 out setup keep-state
20090 214 28854 skipto 50000 udp from any to any dst-port 137-139,445 out keep-state
20100 0 0 skipto 50000 tcp from any to any dst-port 1194 out setup keep-state
20100 0 0 skipto 50000 udp from any to any dst-port 1194 out keep-state
20110 0 0 skipto 50000 tcp from any to any dst-port 111,2049 out setup keep-state
20110 0 0 skipto 50000 udp from any to any dst-port 111,2049 out keep-state
20120 0 0 skipto 50000 tcp from any to any dst-port 6881-6999 out setup keep-state
30000 0 0 allow tcp from any to me dst-port 22 in setup keep-state
30010 0 0 allow udp from any to me dst-port 67,68 in keep-state
30020 0 0 allow icmp from 192.168.0.2 to any in keep-state
40000 1284 289790 deny ip from any to any
50000 238005 226947953 allow ip from any to any
65535 25 7914 allow ip from any to any
Non riesco a trovare da dove provengano queste impostazioni, la disattivazione del firewall non ha alcun effetto.