Bug 3010

Summary:	sshd_config ListenAddress: Netmask is misinterpreted as Port
Product:	Portable OpenSSH	Reporter:	Kurt Stieger <kurt>
Component:	sshd	Assignee:	Assigned to nobody <unassigned-bugs>
Status:	CLOSED DUPLICATE
Severity:	enhancement	CC:	jjelen
Priority:	P5
Version:	7.6p1
Hardware:	Other
OS:	Linux

Description Kurt Stieger 2019-05-16 00:23:41 AEST

Seen on Ubuntu 18.04 (openssh-server, 1:7.6p1-4ubuntu0.2, amd64)

If an IPv4 ListenAddress is configured with netmask suffix (eg. 10.0.0.1/24) the netmask part is used as listening port.

```
$ cat /tmp/sshd_test_conf 
ListenAddress 10.0.0.1/24

$ /usr/sbin/sshd -d -f /tmp/sshd_test_conf 
debug1: sshd version OpenSSH_7.6, OpenSSL 1.0.2n  7 Dec 2017
debug1: private host key #0: ssh-rsa SHA256:...
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:...
debug1: private host key #2: ssh-ed25519 SHA256:...
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-d'
debug1: rexec_argv[2]='-f'
debug1: rexec_argv[3]='/tmp/sshd_test_conf'
debug1: Set /proc/self/oom_score_adj from 0 to -1000
debug1: Bind to port 24 on 10.0.0.1.
Server listening on 10.0.0.1 port 24.
```
For sure, this configuration is wrong, in this case it should be ignored. Starting the service on a port wich was (wrongly) meant as netmask seems to be wrong.

Comment 1 Jakub Jelen 2019-05-16 01:15:56 AEST


*** This bug has been marked as a duplicate of bug 2335 ***

Comment 2 Damien Miller 2021-04-23 15:04:37 AEST

closing resolved bugs as of 8.6p1 release