Re: [44net] SMTP port 25

Turns out you have to specify the interface address for sendmail to respond to, 127.0.0.1 is default so that is why that always worked. I never ran into that one before, That explains this weirdness.. Two boxes on my local LAN with no iptables software firewalls or hardware firewalls between them, and selinux off on both: [root@kb9mwr ~]# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:21:85:9C:60:42 inet addr:192.168.1.100 Bcast:192.168.255.255 Mask:255.255.0.0 inet6 addr: fe80::221:85ff:fe9c:6042/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5421757 errors:0 dropped:0 overruns:0 frame:0 TX packets:4042659 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1012253009 (965.3 MiB) TX bytes:2506193160 (2.3 GiB) Interrupt:58 Base address:0xe000 [root@kb9mwr ~]# telnet localhost 25 Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape character is '^]'. 220 kb9mwr.host.org ESMTP Sendmail 8.13.8/8.13.8; Mon, 11 Aug 2014 19:59:42 -0500 ^] telnet> root@pbx:~ $ telnet 192.168.1.100 25 Trying 192.168.1.100... telnet: connect to address 192.168.1.100: Connection refused telnet: Unable to connect to remote host: Connection refused I was well aware that most ISP's block that port but was really stumped as to why to PC's on the same network could not talk to each other on that port yet could on all other ports. You learn something new every day.