I'm trying to make a mailserver with postfix/dovecot but I'm stuck. The problem is I cannot connect to some of the ports I want open, for example 587. As far as I can tell the port is open and listening, and the firewall has the port opened. I know that some years ago the ISP blocked all ports except those explicitly requested as opened, but now they swear that they're not blocking anything anymore.
If I try to connect locally via telnet localhost 587 I get a proper connection. The same if I replace localhost with the external IP address (don't know if it matters).
Here's some diagnostic information showing that it should work:
> netstat -an4
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:4190 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:993 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:995 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:587 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:110 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:465 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
udp 0 0 127.0.0.1:323 0.0.0.0:*
> firewall-cmd --list-all
public (active)
target: default
icmp-block-inversion: no
interfaces: enp5s0
sources:
services: dhcpv6-client ssh
ports: 21/tcp 443/tcp 80/tcp 49152-65534/tcp 25/tcp 110/tcp 143/tcp 993/tcp 995/tcp 465/tcp 587/tcp
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
> ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp5s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
inet xxx.xxx.xxx.xxx/24 brd xxx.xxx.xxx.255 scope global noprefixroute enp5s0
valid_lft forever preferred_lft forever
inet6 xxxx::xxxx:xxxx:xxxx:xxxx/64 scope link noprefixroute
valid_lft forever preferred_lft forever
And last but not least, the raw dump from iptables - this one I'm not skilled enough to decipher, but perhaps someone can notice a problem there.
> iptables --list -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
INPUT_direct all -- 0.0.0.0/0 0.0.0.0/0
INPUT_ZONES_SOURCE all -- 0.0.0.0/0 0.0.0.0/0
INPUT_ZONES all -- 0.0.0.0/0 0.0.0.0/0
DROP all -- 0.0.0.0/0 0.0.0.0/0 ctstate INVALID
REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
FORWARD_direct all -- 0.0.0.0/0 0.0.0.0/0
FORWARD_IN_ZONES_SOURCE all -- 0.0.0.0/0 0.0.0.0/0
FORWARD_IN_ZONES all -- 0.0.0.0/0 0.0.0.0/0
FORWARD_OUT_ZONES_SOURCE all -- 0.0.0.0/0 0.0.0.0/0
FORWARD_OUT_ZONES all -- 0.0.0.0/0 0.0.0.0/0
DROP all -- 0.0.0.0/0 0.0.0.0/0 ctstate INVALID
REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
OUTPUT_direct all -- 0.0.0.0/0 0.0.0.0/0
Chain FORWARD_IN_ZONES (1 references)
target prot opt source destination
FWDI_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
FWDI_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
Chain FORWARD_IN_ZONES_SOURCE (1 references)
target prot opt source destination
Chain FORWARD_OUT_ZONES (1 references)
target prot opt source destination
FWDO_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
FWDO_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
Chain FORWARD_OUT_ZONES_SOURCE (1 references)
target prot opt source destination
Chain FORWARD_direct (1 references)
target prot opt source destination
Chain FWDI_public (2 references)
target prot opt source destination
FWDI_public_log all -- 0.0.0.0/0 0.0.0.0/0
FWDI_public_deny all -- 0.0.0.0/0 0.0.0.0/0
FWDI_public_allow all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
Chain FWDI_public_allow (1 references)
target prot opt source destination
Chain FWDI_public_deny (1 references)
target prot opt source destination
Chain FWDI_public_log (1 references)
target prot opt source destination
Chain FWDO_public (2 references)
target prot opt source destination
FWDO_public_log all -- 0.0.0.0/0 0.0.0.0/0
FWDO_public_deny all -- 0.0.0.0/0 0.0.0.0/0
FWDO_public_allow all -- 0.0.0.0/0 0.0.0.0/0
Chain FWDO_public_allow (1 references)
target prot opt source destination
Chain FWDO_public_deny (1 references)
target prot opt source destination
Chain FWDO_public_log (1 references)
target prot opt source destination
Chain INPUT_ZONES (1 references)
target prot opt source destination
IN_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
IN_public all -- 0.0.0.0/0 0.0.0.0/0 [goto]
Chain INPUT_ZONES_SOURCE (1 references)
target prot opt source destination
Chain INPUT_direct (1 references)
target prot opt source destination
REJECT tcp -- 0.0.0.0/0 0.0.0.0/0 multiport dports 22 match-set fail2ban-sshd src reject-with icmp-port-unreachable
Chain IN_public (2 references)
target prot opt source destination
IN_public_log all -- 0.0.0.0/0 0.0.0.0/0
IN_public_deny all -- 0.0.0.0/0 0.0.0.0/0
IN_public_allow all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
Chain IN_public_allow (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:21 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:443 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpts:49152:65534 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:25 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:110 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:143 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:993 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:995 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:465 ctstate NEW
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:587 ctstate NEW
Chain IN_public_deny (1 references)
target prot opt source destination
Chain IN_public_log (1 references)
target prot opt source destination
Chain OUTPUT_direct (1 references)
target prot opt source destination
My question is - after all this, is there still some doubt that my server might be blocking the connections on its own? If yes, how do I find that out? Or is this conclusive enough that I need to go raise hell with the ISP?
0 Answers