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Jaroslav Kucera's questions

Martin Hope
Jaroslav Kucera
Asked: 2022-11-25 10:28:33 +0800 CST
  • 7

On the RHEL 8 and previous it is usual, that the SSH host keys in /etc/ssh are generated automatically by sshd service when missing. Usually there should be:

/etc/ssh/ssh_host_ecdsa_key
/etc/ssh/ssh_host_ecdsa_key.pub
/etc/ssh/ssh_host_ed25519_key
/etc/ssh/ssh_host_ed25519_key.pub
/etc/ssh/ssh_host_rsa_key
/etc/ssh/ssh_host_rsa_key.pub

Restart of the node or even systemctl restart sshd should be sufficient.

But as of the minor version RHEL 8.7 this may not work any more and the sshd crashes complaining about missing host keys in the journal log. Why? How can I solve this?

ssh
Martin Hope
Jaroslav Kucera
Asked: 2017-10-07 02:27:50 +0800 CST
  • 1

We have RHEL 6.5 server which serves as local YUM server and uses httpd for the purpose. It's running on port 6809. And until yesterday it was running fine. One of my colleague was doing some additional deployment on different server which is supposed to use the YUM server, but the yum couldn't connect. He admits, that he was also doing some work on the YUM server, but he's not aware of doing something related to httpd configuration.

So we realized that the httpd on the YUM server isn't running and refuses to start:

# service httpd start
Starting httpd: (98)Address already in use: make_sock: could not bind to address 172.29.84.41:6809
no listening sockets available, shutting down
Unable to open logs
                                                           [FAILED]

We've already checked that the port 6809 isn't occupied with lsof and netstat:

lsof -iTCP -sTCP:LISTEN -P -n

and

netstat -tupan | grep -Ei LISTEN

All clear, no other process.

We've also greped for Listen in /etc/httpd directory and there is only single directive with 6809 port:

httpd# grep -Ri listen *
conf/httpd.conf:# Listen: Allows you to bind Apache to specific IP addresses and/or
conf/httpd.conf:# Change this to Listen on specific IP addresses as shown below to
conf/httpd.conf:#Listen 12.34.56.78:80
conf/httpd.conf:#Listen 80
conf.d/ssl.conf:# When we also provide SSL we have to listen to the
conf.d/ssl.conf:#Listen 443
conf.d/yum.conf:Listen yum-server:6809
logs/test.log:read(4, "Listen yum-server:6809\nServe"..., 4096) = 496
logs/test.log:listen(3, 511)                          = 0
logs/test.log:write(2, "no listening sockets available, "..., 46no listening sockets available, shutting down
Binary file modules/mod_info.so matches
Binary file modules/mod_wsgi.so matches
Binary file modules/mod_proxy_ftp.so matches
Binary file modules/mod_cgid.so matches

So it isn't a duplicate.

The IP is local to the server.

No httpd process is running either.

We've also reinstalled the httpd RPM.

SELinux isn't running:

# sestatus
SELinux status:                 disabled

Please, what else could be wrong?

Thank you very much for your advices.

Add 2:

To @André Fernandes:

# lsof -n -P -i :6809
# find /etc/httpd -type f | xargs grep Listen
/etc/httpd/conf.d/ssl.conf:#Listen 443
/etc/httpd/conf.d/yum.conf:Listen yum-server:6809
/etc/httpd/conf/httpd.conf:# Listen: Allows you to bind Apache to specific IP addresses and/or
/etc/httpd/conf/httpd.conf:# Change this to Listen on specific IP addresses as shown below to
/etc/httpd/conf/httpd.conf:#Listen 12.34.56.78:80
/etc/httpd/conf/httpd.conf:#Listen 80

To @MadHatter I've shortened the output and removed real names. But the alias yum_server is there:

# cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1       localhost.somewhe.re localhost trap-host
172.29.84.41    <FQDN and name> yum-server <other aliases>
...

Add 3:

The ip addr show output:

# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000
    link/ether 3c:4a:92:ed:c0:28 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000
    link/ether 3c:4a:92:ed:c0:28 brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond1 state UP qlen 1000
    link/ether 68:b5:99:c6:42:4c brd ff:ff:ff:ff:ff:ff
5: eth3: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond1 state UP qlen 1000
    link/ether 68:b5:99:c6:42:4c brd ff:ff:ff:ff:ff:ff
6: eth4: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond2 state UP qlen 1000
    link/ether 68:b5:99:c6:42:4e brd ff:ff:ff:ff:ff:ff
7: eth5: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond2 state UP qlen 1000
    link/ether 68:b5:99:c6:42:4e brd ff:ff:ff:ff:ff:ff
8: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
    link/ether 3c:4a:92:ed:c0:28 brd ff:ff:ff:ff:ff:ff
    inet 172.29.84.41/26 brd 172.29.84.63 scope global bond0
9: bond1: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
    link/ether 68:b5:99:c6:42:4c brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.1/24 brd 192.168.1.255 scope global bond1
10: bond2: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
    link/ether 68:b5:99:c6:42:4e brd ff:ff:ff:ff:ff:ff
    inet 10.1.212.71/24 brd 10.1.212.255 scope global bond2
port