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C7: NM and changing MAC addresses
by Tom Yates 11 Oct '21

11 Oct '21

i need a way to stop anything from changing my external MAC address, as my ISP is extremely sensitive to additional MAC addresses appearing on my external NIC. i have done sudo nmcli conn mod eno1 802-3-ethernet.cloned-mac-address permanent and it's improved matters, but here's an example of it going wrong even so, from "tcpdump -n -n -e -i eno1 src 185.219.108.121" (which is my ipv4): 10:23:58.210653 ac:1f:6b:6c:5a:6e > bc:30:5b:f7:3e:c8, ethertype IPv4 (0x0800), length 114: 185.219.108.121.53002 > 198.252.206.25.443: Flags [P.], seq 2018:2066, ack 5333, win 501, options [nop,nop,TS val 4035938817 ecr 1709670339], length 48 10:23:58.405154 ac:1f:6b:6c:5a:6e > bc:30:5b:f7:3e:c8, ethertype IPv4 (0x0800), length 66: 185.219.108.121.44534 > 216.58.212.234.443: Flags [.], ack 21641, win 501, options [nop,nop,TS val 805137946 ecr 1062125308], length 0 10:23:58.447030 ac:1f:6b:6c:58:2d > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 60: Request who-has 185.219.108.1 tell 185.219.108.121, length 46 10:23:58.447466 ac:1f:6b:6c:58:2d > bc:30:5b:f7:3e:c8, ethertype IPv4 (0x0800), length 342: 185.219.108.121.68 > 185.219.108.1.67: BOOTP/DHCP, Request from ac:1f:6b:6c:58:2d, length 300 10:23:58.629131 ac:1f:6b:6c:5a:6e > bc:30:5b:f7:3e:c8, ethertype IPv4 (0x0800), length 98: 185.219.108.121 > 8.8.8.8: ICMP echo request, id 105, seq 67, length 64 note the first two frames coming from ac:1f:6b:6c:5a:6e, the real MAC address, which has been happily all over the headers of the previous several thousand frames, but then two frames from ac:1f:6b:6c:58:2d, which *utterly* screw up my connection to my ISP. the old MAC address continues to be on some of the outgoing traffic. i have some grounds for thinking that the first or second frame with the "bad" mac address is always a BOOTP/DHCP frame, so i'm open to the idea that this is dhclient being "helpful", rather than NM. does anyone have any idea which daemon or service is responsible for this MAC-rebadging, and/or how i might stop it? -- Tom Yates - https://www.teaparty.net

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Postfix and virtual mail boxes.
by Rob Kampen 11 Oct '21

11 Oct '21

Hi, not sure this is the best place to go for my problem, but hoping someone can point me to the correct or better place. I have two currently working CentOS 7 based email servers that host a number of virtual domains and users and delivers mail just fine - for correctly addressed vmail inboxes AND for alias addressed emails and domains. These all use postfix, dovecot, amavisd, clamAV, spamassassin, mysql (mariadb) and roundcubemail I use port 25 for the world email delivery - no auth needed as only accepts hosted virtual domain addressed email. and port 587 for user client MUA to send mail - smtp with STARTTLS auth needed port 993 for MUA IMAP access to account mail boxes A couple of weeks ago I rolled up a new minimal virtual server (also CentOS 7) and basically copied the same setup as the other two and have now spent far too long trying to get it going. My initial problem was that I set up mydestination to include $mydomain - this has the consequence of seeing any mail@$mydomain as local email and trying to deliver to the local machine rather than the vmail inboxes. So after setting up a new domain just for the MX we moved on. All three installations use mysql (mariadb) as the data store for domains, alias domains, user vmail accounts, and forwardings (virtual alias mapping) The mysql bits work just fine as I can send mail from an MUA client and they deliver correctly via an authenticated session on port 587 - i.e to any world email address AND to local vmail boxes, including those addressed via an alias and/or alias domain. What fails to work on the new installation, but works fine on my two legacy servers, is mail addressed via an alias. Specifically an alias domain. Even adding the complete alias email address to the forwardings table doesn't work. e.g. let's say we have an email domain '@example.com' and an alias domain '@example.org'. Needed so I can migrate my clients from one server to the other in a staged manner. Thus the new server is set up to operate as the MX for @example.org and @example.com but needs to alias redirect the incoming emails being sent to fred(a)example.org and deliver them to the vmail location for fred(a)example.com (i.e. we have no vmail locations for @example.org only for @example.com So if I send a test email via my MUA (using port 587 and hence authenticated) it does the alias lookups and translations needed and correctly delivers the mail. However if I send an email to fred(a)example.org from say a gmail account, it arrives at my new server and promptly gets bounced with a 550 5.7.1 error - no such email address. After doing diff on the main.cf and master.cf from all three servers the only differences are the myhostname, mynetworks (new one is dual stack IP4/IPv6 and thus includes [::1]/128), smtpd_tls certificate names, and the virtual_uid_maps - all expected and accounted for. master.cf are identical Many dozens of google searches and reading far too many pages, has left me with no idea why my new server doesn't accept alias directed emails via port 25. All the documentation indicates that alias lookups and translations are performed by postfix - all the time. receive_override_options is not set. Any suggestions of things to check or test would be welcome. TIA Rob

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Re: [CentOS] Infiniband
by Mark Woolfson 09 Oct '21

09 Oct '21

Hello, Please can someone help. I have a large server cluster running CentOS 6.4 and CentOS 6.6 using 10GbE. I want to upgrade to Infiniband. What Mellanox ConnectX VPI is supported natively on these OS's? What Mellanox ConnectX VPI is supported using an additional device driver on these OS's? Mark -- This email has been checked for viruses by AVG. https://www.avg.com

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Re: [CentOS] Postfix and virtual mail boxes.
by Gionatan Danti 08 Oct '21

08 Oct '21

Il 2021-10-07 12:40 Rob Kampen ha scritto: > mydestination = localhost localhost.localdomain > mydomain = example.org > myhostname = mx.example.org > mynetworks = 127.0.0.0/8, [::1]/128 Not that I expect it to be the cause, but you need a coma between "localhost" and "localhost.localdomain" in mydestination. > I had originally only used "postconf -n" as it is MUCH smaller than > postconf , however it still shows no material differences. Yeah, it seem the config are very similar (with the exception of virtual_alias_maps, which you explained). Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti(a)assyoma.it - info(a)assyoma.it GPG public key ID: FF5F32A8

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how to set a directory to system_u?
by hw 04 Oct '21

04 Oct '21

Hi, I'm trying to a lable a directory for ejabberd to store files that were uploaded with the http_upload module. Apparently I should set this to 'system_u:object_r:ejabberd_var_lib_t:s0' since all the files in /var/lib/ejabberd are. So: ls -laZ /srv/data/ unconfined_u:object_r:ejabberd_var_lib_t:s0 320 Jul 29 23:55 ejabberd semanage fcontext -a -t ejabberd_var_lib_t -s system_u '/srv/data/ejabberd(/.*)?' restorecon -R /srv/data/ejabberd/ ls -laZ /srv/data/ unconfined_u:object_r:ejabberd_var_lib_t:s0 320 Jul 29 23:55 ejabberd Why doesn't this work? Why can't they finally write some decent tool to use selinux that allows us to keep it enabled??? How can I set up the directory for ejabberd to store files in?

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Installing openLDAP on Centos 7
by Gary Stainburn 03 Oct '21

03 Oct '21

I am following the howto on https://linuxhostsupport.com/blog/how-to-install-ldap-on-centos-7/ which matches a number of other howto's. I have tried this on two Centos 7 boxes and both fail in the same way when trying to set the certificates. I have tried <insert search engine here> without success. I found that by adding '-d 1' you enable debugging, but the debugging did not help. Anyone got any suggestions? All steps prior to this worked successfully. Gary [root@eddie ldap]# ldapmodify -Y EXTERNAL -H ldapi:/// -f certs.ldif SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 modifying entry "cn=config" ldap_modify: Other (e.g., implementation specific) error (80) [root@eddie ldap]# cat certs.ldif dn: cn=config changetype: modify replace: olcTLSCertificateFile olcTLSCertificateFile: /etc/openldap/certs/myldap.ringways.com.cert dn: cn=config changetype: modify replace: olcTLSCertificateKeyFile olcTLSCertificateKeyFile: /etc/openldap/certs/myldap.ringways.com.key [root@eddie ldap]# ll /etc/openldap/certs/ total 72 -rw-r--r--. 1 ldap ldap 65536 Sep 30 11:19 cert8.db -rw-r--r--. 1 ldap ldap 16384 Sep 30 11:19 key3.db -rw-r--r--. 1 ldap ldap 1493 Sep 30 12:16 myldap.ringways.com.cert -rw-r--r--. 1 ldap ldap 1704 Sep 30 12:16 myldap.ringways.com.key -r--r-----. 1 ldap ldap 45 Jul 29 2020 password -rw-r--r--. 1 ldap ldap 16384 Jul 29 2020 secmod.db [root@eddie ldap]#

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kvm/qemu: USB passthrough
by hw 01 Oct '21

01 Oct '21

Hi, I'm trying to pass an USB port (or hub) to a kvm/qemu guest, to no avail. To find out which physical port I can use, I plugged a device into the port, and dmesg on the host says: usb 3-3: new high-speed USB device number 10 using xhci_hcd Which device on the host is that? lspci | grep -i usb 00:14.0 USB controller: Intel Corporation C610/X99 series chipset USB xHCI Host Controller (rev 05) 00:1a.0 USB controller: Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #2 (rev 05) 00:1d.0 USB controller: Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #1 (rev 05) lsusb -t /: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 5000M /: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/15p, 480M |__ Port 6: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M |__ Port 13: Dev 3, If 0, Class=Human Interface Device, Driver=usbhid, 12M |__ Port 14: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 12M /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/3p, 480M |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/3p, 480M |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M I tried to add the USB port to the domain by editing it and adding: <hostdev mode='subsystem' type='usb' managed='yes'> <source> <vendor id='0x1d6b'/> <product id='0x0003'/> </source> </hostdev> The domain (a windows 10) starts with that, but no USB port shows up. The documentation about this totally sucks, and I couldn't find any answer that would work with a search engine, either. When I try to use the bus and port attributes, I'm getting domain verification errors from virsh edit. Is it even possible to pass an usb port or hub through? I just need one USB port in the guest.

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Upgrading CentOS from 7 to 8
by Gestió Servidors 30 Sep '21

30 Sep '21

Hi, I'm doing some tests of upgrading CentOS from 7 to 8 reading this step-by-step guide: https://netshopisp.medium.com/how-to-upgrade-linux-servecentos-7-to-centos-… I'm trying this upgrade in a VM, so I can save "snapshots" and restart in a past saved point. However, all my test ends wrong, exacly in Step 4 when I run "rpm -e `rpm -q kernel`". Then, systems says that some packages are kernel dependencies. After I remove that dependencies, I can't remove kernel... Anybody has tested process upgrade from 7 to 8? Thanks.

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Re: [CentOS] how to display/create DUID?
by hw 30 Sep '21

30 Sep '21

On Thursday, September 30, 2021 2:31:48 AM CEST Kenneth Porter wrote: > --On Wednesday, September 29, 2021 11:59 PM +0200 hw <hw(a)gc-24.de> wrote: > > Is that my lack of understanding or are these DUIDs really a rather > > stupid idea? > > > > And how are we actually supposed to set up static leases with DHCPv6? > > I recommend asking over on the ISC DHCP lists where you're likely to find > much more expertise on the subject in these dark corners of the standards. Hm ok, maybe I'll try that, thanks.

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Re: [CentOS] how to display/create DUID?
by hw 30 Sep '21

30 Sep '21

On Sunday, September 19, 2021 6:53:45 PM CEST Kenneth Porter wrote: > --On Sunday, September 19, 2021 3:02 PM +0200 hw <hw(a)gc-24.de> wrote: > > None of this is working because the server isn't running a DHCPv6 server, > > and there seems to be no file in /var/lib/NetworkManager that would seem > > to be helpful. > > > > Isn't there a tool that creates the DUID and prints it? This can't be > > too difficult ... > > I found this thread that suggests that NetworkManager computes it every > time unless it's manually overridden: > > <https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/135> That might mean that I would need to extract the functions from the soruces of dhclient to make a program that prints DUID(s) for the machine you run it on. ... But that isn't so easy. Maybe I can find out how to create a DUID and write something in perl; it doesn't seem to be too complicated in the source. The comment is interesting: /* * The "best" default DUID, since we cannot predict any information * about the system (such as whether or not the hardware addresses are * integrated into the motherboard or similar), is the "LLT", link local * plus time, DUID. For real stateless "LL" is better. * * Once generated, this duid is stored into the state database, and * retained across restarts. * * For the time being, there is probably a different state database for * every daemon, so this winds up being a per-interface identifier...which * is not how it is intended. Upcoming rearchitecting the client should * address this "one daemon model." */ I don't understand what the point of a DUID is which is /not/ a per-interface identifier. When I assign addresses via DHCP, I don't want them to end up being assigned anywhere else than to the interface they need to be assigned to. What is intended with these DUIDs? > Based on that, nmtui-connect might do what you want. That seems to only allow to bring up or down a connection but doesn't display DUIDs?

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