Hello Friends:
The following had no issues when running atop Fedora-33. It began after an upgrade to Fedora-36. Perhaps there was a networking change (I haven’t kept track lately).
I have two Linux computers running Fedora-36, as follows:
- 192.168.0.16 – host01 (Open ports: 22, 443)
- 192.168.0.31 – host02
On my ISP ROUTER, I PORT-FORWARD requests to port 22 & 443 to host01.
Here is my issue issue:
From within host02, there are no access issues:
user@host02$ nc -vz MY-ISP-WAN-IP 443
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connected / succeeded to MY-ISP-WAN-IP:443.
Ncat: 0 bytes sent, 0 bytes received in 0.04 seconds.
user@host02$ nc -vz MY-ISP-WAN-IP 22
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connected / succeeded to MY-ISP-WAN-IP:22.
Ncat: 0 bytes sent, 0 bytes received in 0.04 seconds.
But from within host01, itself the destination of the PORT-FORWARDS, it gets stuck:
user@host01$ nc -vz MY-ISP-WAN-IP 443
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: TIMEOUT.
user@host01$ nc -vz MY-ISP-WAN-IP 22
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: TIMEOUT.
The same succeeds when specifying it’s own name host01:
root@host01# nc -vz host01 443
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connected / succeeded to 192.168.0.16:443.
Ncat: 0 bytes sent, 0 bytes received in 0.03 seconds.
root@host01# nc -vz host01 22
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connected / succeeded to 192.168.0.16:22.
Ncat: 0 bytes sent, 0 bytes received in 0.03 seconds.
Additional information that may be helpful:
user@host01$ sudo ifconfig -a
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether aa:bb:cc:dd:ee:ff txqueuelen 1000 (Ethernet)
RX packets 261 bytes 22155 (21.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 84 bytes 10593 (10.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 18 memory 0xfb100000-fb120000
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 8 bytes 648 (648.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 8 bytes 648 (648.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lxcbr0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.16 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 ****::****:***:****:**** prefixlen 64 scopeid 0x20<link>
ether aa:bb:cc:dd:ee:ff txqueuelen 1000 (Ethernet)
RX packets 261 bytes 17457 (17.0 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 88 bytes 11397 (11.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
user@host01$ sudo brctl show
bridge name bridge id STP enabled interfaces
lxcbr0 8000.aabbccddeeff no eth0
So PORT-FORWARD requests succeed in getting to the destination Host & Ports, except when the requests originate from that destination Host itself.
Again, on Fedora-33 this worked well. It may have to do with source and destination IPs and/or MACs being the same, but I don’t want to steer anyone’s thoughts necessarily in any direction. Just mentioning it.
Any ideas? Thank you!