Discuss June 2020

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103 participants
90 discussions

firewalld / iptables / nftables
by Leon Fauster 09 Jun '20

09 Jun '20

Despite that the migration of our applications comes with a significant workload. It seems that also every aspect of common services had changed with EL8. In EL8 firewalld uses nftables as backend. I wonder why iptables does not list any rules while also configured to use nftables as backend. # iptables -V iptables v1.8.2 (nf_tables) # firewall-cmd --list-all |egrep -o '22|ssh' ssh # nft list ruleset | egrep -o '22|ssh' ssh # iptables -L -n | egrep -o '22|ssh' <EMPTY> Any hints? -- Leon

4 4

Trying to get bride network on CentOS 7 working with virt-manager
by Jerry Geis 09 Jun '20

09 Jun '20

I have these interfaces listed. eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.8 netmask 255.255.252.0 broadcast 192.168.3.255 inet6 fe80::e2d5:5eff:fe63:abe5 prefixlen 64 scopeid 0x20<link> ether e0:d5:5e:63:ab:e5 txqueuelen 1000 (Ethernet) RX packets 42411243 bytes 4701898681 (4.3 GiB) RX errors 0 dropped 156 overruns 0 frame 0 TX packets 78372982 bytes 34946337897 (32.5 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 16 memory 0x92f00000-92f20000 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:fc:34:af txqueuelen 1000 (Ethernet) RX packets 132792 bytes 337411780 (321.7 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 138593 bytes 742263806 (707.8 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.100.1 netmask 255.255.255.0 broadcast 192.168.100.255 ether 52:54:00:9c:39:02 txqueuelen 1000 (Ethernet) RX packets 206217 bytes 132308800 (126.1 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 105448 bytes 197008661 (187.8 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0-nic: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 ether 52:54:00:fc:34:af txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 When I bring up virt-manager, got settings for my VM, and for "Network Source" I select "Specify Shared Device Name" and I have tried the virbr0 and clicked apply and boot the machine. I get networking but not bridged networking - not a 192.168.1.X address. Is there something I missed ? Thanks, Jerry

2 2

Postfix restrictions
by Nicolas Kovacs 09 Jun '20

09 Jun '20

Hi, I'm currently fine-tuning my mail server (Postfix and Dovecot on CentOS 7). SPF, DKIM and DMARC work fine, now I'd like to limit the spam tsunami. Besides the official Postfix documentation, I've read a few articles about Postfix spam restrictions, namely these : https://www.linuxbabe.com/mail-server/block-email-spam-postfix https://wiki.centos.org/HowTos/postfix_restrictions After some experimenting, here's what I currently have on my test server: --8<----- /etc/postfix/main.cf ----------------------------- ... smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks, permit_sasl_authenticated, check_helo_access hash:/etc/postfix/helo_access reject_invalid_helo_hostname, reject_non_fqdn_helo_hostname, reject_unknown_helo_hostname smtpd_sender_restrictions = permit_mynetworks, permit_sasl_authenticated, check_sender_access hash:/etc/postfix/sender_access, reject_unknown_sender_domain, reject_unknown_reverse_client_hostname, reject_unknown_client_hostname smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, check_client_access hash:/etc/postfix/rbl_override, reject_rhsbl_helo dbl.spamhaus.org, reject_rhsbl_reverse_client dbl.spamhaus.org, reject_rhsbl_sender dbl.spamhaus.org, reject_rbl_client zen.spamhaus.org --8<-------------------------------------------------------- Before committing this configuration to my main server, I thought I'd share this configuration on the list. Maybe the Postfix gurus among you have the odd comment to make. My aim is simply to eliminate as much spam as possible (that is, before adding SpamAssassin) while keeping false positives to a minimum. Any suggestions ? Niki -- Microlinux - Solutions informatiques durables 7, place de l'église - 30730 Montpezat Site : https://www.microlinux.fr Mail : info(a)microlinux.fr Tél. : 04 66 63 10 32 Mob. : 06 51 80 12 12

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EPEL repository: Failure to download metadata
by Jay Hart 08 Jun '20

08 Jun '20

Trying to install certbot, for Lets Encrypt certificate installation. How do I fix the below repo issue? I have not been successful tracking down this issue using google. [root@dream postfix]# yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm CentOS-8 - AppStream 0.0 B/s | 0 B 00:10 Failed to download metadata for repo 'AppStream' Error: Failed to download metadata for repo 'AppStream' [root@dream postfix]# ^C [root@dream postfix]# ls /etc/yum.repos.d/ CentOS-AppStream.repo CentOS-CR.repo CentOS-Extras.repo CentOS-Media.repo CentOS-Vault.repo CentOS-Base.repo CentOS-Debuginfo.repo CentOS-fasttrack.repo CentOS-PowerTools.repo CentOS-centosplus.repo CentOS-Devel.repo CentOS-HA.repo CentOS-Sources.repo [root@dream postfix]# dnf repolist CentOS-8 - AppStream 0.0 B/s | 0 B 00:25 Failed to download metadata for repo 'AppStream' Error: Failed to download metadata for repo 'AppStream' Thanks, Jay

1 2

Logitech webcam for use with CentOS 7
by H 08 Jun '20

08 Jun '20

I am thinking of buying a Logitech C920S Pro HD or C922 webcam for the necessary video conferencing. Is anyone using that with Zoom or perhaps with Jitsi? Do I need drivers? Any issues? Thank you.

7 6

live centos 8?
by Michael Hennebry 07 Jun '20

07 Jun '20

Is there a live centos 8? If so, where? -- Michael hennebry(a)web.cs.ndsu.NoDak.edu "Sorry but your password must contain an uppercase letter, a number, a haiku, a gang sign, a heiroglyph, and the blood of a virgin." -- someeecards

2 3

perl-Curses in C8?
by Mike McCarthy, W1NR 06 Jun '20

06 Jun '20

Are there any repos that would have perl-Curses for CentOS 8? It was always available in epel but not anymore. Thanks, Mike

2 1

How to disable dhcpv6-client on Centos 8
by Jay Hart 06 Jun '20

06 Jun '20

Machine is an internal server with zero need to provide or receive ip addresses using dhcp (all IPs are hard coded). Question: how do I disable dhcpv6-client on this box? [user@boxname user]# firewall-cmd --list-all public (active) target: default icmp-block-inversion: no interfaces: enp2s0 sources: services: cockpit dhcpv6-client http https ssh ports: protocols: masquerade: no forward-ports: source-ports: icmp-blocks: rich rules: Thanks, Jay

2 2

Bridge network for virt-manager
by Jerry Geis 05 Jun '20

05 Jun '20

Hello. I desire to get bridge network working using virt-manager. Centos 7 and centos 7 guest. >From researching I think I need to have a ifcfg-br0 file like this ? cat ifcfg-br0 DEVICE=nm-bridge0 STP=no TYPE=Bridge BOOTPROTO=none IPADDR=192.168.1.8 PREFIX=32 GATEWAY=192.168.1.1 IPV6INIT=no NAME=br0 ONBOOT=yes DELAY=0 Is that for sure needed ? The use that nm-bridge0 as the network name? I dont want to mess up my current setup. Thanks, Jerry

6 7

Re: [CentOS] migrating from sendmail to postfix, centos 6 to centos 8
by Pete Biggs 05 Jun '20

05 Jun '20

On Fri, 2020-06-05 at 07:32 -0500, Chuck Campbell wrote: > On 6/4/2020 8:58 AM, Pete Biggs wrote: > > > Fair enough, and I now understand the issues with root receiving and > > > handling emails. The problem with the alias is that ALL emails are being > > > sent out to my ISP, and on to the particular user. > > Even for local users that are in /etc/passwd? > Yes, I only have two local users, and email I send on the box ends up at > the outside ISP, then comes back via fetchmail, and procmail. I can read > it with IMAP from outside. I guess I'll live with this. So even if you do something like mail chuck at the command line (with whatever user has a local account) it still gets sent to the ISP? > I'm sure it is the RelayHost or RelayDomains that forwards the email > outbound to my ISP. relay_host is the host that mail is sent to if it can't be delivered elsewhere. relay_domains is a list of domains the host will relay mail to. > If I set up a local only account, those emails try > to go outbound as well, but are rejected as there is no registered user > of that name at my ISP. In /etc/postfix/main.cf what is 'local_recipient_maps' set to? Also, what about 'mydestination' If you look in /var/log/maillog what does a message log for a local user look like when sent using the mail command? P.

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Discuss June 2020