HON95-wiki/config/linux-servers/applications.md

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title: Linux Server Applications breadcrumbs:

• title: Configuration
• title: Linux Servers --- {% include header.md %}

TODO Migrate the rest of the config notes from the old Google Doc.

Using

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• Debian 10 Buster

Ceph

See Storage: Ceph.

Certbot

Setup

1. Install: apt install certbot
2. (Optional) Add post-update hook: In /etc/letsencrypt/cli.ini, add renew-hook = systemctl reload nginx or equivalent.

Usage

• Create using HTTP challenge (auto-renewable): certbot -d <domain> --preferred-challenges=http --webroot --webroot-path=<webroot> certonly
• Create using DNS channelge (not auto-renewable): certbot -d <domain> --preferred-challenges=dns --manual certonly
• Dry-run renew: certbot renew --dry-run [--staging]
• Revoke certificate: certbot revoke --cert-path <cert>

Docker & Docker Compose

TODO

Setup

1. Install Docker (Debian).
2. Install Docker Compose.
3. Install Docker Compose command completion.
4. (Optional) Setup swap limit:
   • If docker info contains WARNING: No swap limit support, it's not working and should maybe be fixed.
   • It incurs a small performance degredation and is optional but recommended.
   • In /etc/default/grub, add cgroup_enable=memory swapaccount=1 to GRUB_CMDLINE_LINUX.
   • Run update-grub and reboot.

Docker Compose No-Exec Tmp-Dir Fix

Docker Compose will fail to work if /tmp has noexec.

1. Move /usr/local/bin/docker-compose to /usr/local/bin/docker-compose-normal.
2. Create /usr/local/bin/docker-compose with the contents below and make it executable.

3. Create the new TMPDIR dir.

   #!/bin/bash
   # Some dir without noexec
   export TMPDIR=/var/lib/docker-compose-tmp
   /usr/local/bin/docker-compose-normal "$@"
   

Fail2ban

Setup

1. Install fail2ban.
2. Fix the firewall first so it configures itself correctly wrt. firewall blocking.
3. Check the status with fail2ban-client status [sshd].

Intel SSD Data Center Tool (isdct)

Setup

1. Download the ZIP for Linux from Intel's site.
2. Install the AMD64 deb package.

Usage

• Command syntax: isdct <verb> [options] [targets] [properties]
  • Target may be either index (as seen in show) or serial number.
• Show all SSDs: isdct show -intelssd
• Show SSD properties: isdct show -all -intelssd [target]
• Show health: isdct show -sensor
• Upgrade firmware: isdct load -intelssd <target>
• Set physical sector size: isdct set -intelssd <target> PhysicalSectorSize=<512|4096>
  • 4k is generally the most optimal choice.
• Prepare a drive for removal by putting it in standby: isdct start -intelssd <target> -standby
• Show speed: isdct show -a -intelssd [target] | grep -i speed
• Fix SATA 3.0 speed: isdct set -intelssd <target> PhySpeed=6
  • Check before and after either with isdct or smartctl.

Change the Capacity

1. Remove all partitions from the drive.
2. Remove all data: isdct delete -intelssd <target>
3. (Optional) Set the physical sector size: isdct set -intelssd <target> PhysicalSectorSize=<512|4096>
4. Set the new size: isdct set -intelssd <target> MaximumLBA=<size>
   • If this fails, run isdct set -system EnableLSIAdapter=true. It will add another "version" of the SSDs, which you can try again with.
   • The size can be specified either as "native", the LBA count, percent (x%) or in gigabytes (xGB). Use "native" unless you have a reason not to.
5. Prepare it for removal: isdct start -intelssd <target> -standby
6. Reconnect the drives or restart the system.

ISC DHCP Server

Notes

• DHCPv4 uses raw sockets, so it bypasses the firewall (i.e. no firewall rules are needed). DHCPv6, however, does not. This includes the respective clients as well.
• The DHCPv6 server is typically used with radvd for router advertisements.

Setup

1. Install and enable isc-dhcp-server.
2. Setup config files:
   • DHCPv4: /etc/dhcp/dhcpd.conf
   • DHCPv6 (optional): /etc/dhcp/dhcpd6.conf
3. If using systemd-networkd, fix wrong startup order:
   • TODO

Configuration

• Always specify the authorative statement in subnet declarations so that the server will reply with DHCPNAK for misconfigured clients. This may significantly reduce reconfiguration delay when a client moves between subnets.
• For range6, prefer using CIDR notation. If using range notation, try to align the start and end on a CIDR block to avoid excessive memory usage.
• DHCPv6 uses lease pools of 9973 entries, so using range sizes below this number may be preferable as a very general reference. /116 gives 8191 addresses.

NFS

The instructions below use NFSv4 without Kerberos. This is not considered secure at all and should only be used on trusted networks and systems.

Server

Setup

1. (Recommended) Use NTP on both server and clients to make sure the clocks are synchronized.
2. Install: apt install nfs-kernel-server portmap
   • "portmap" is only required for NFSv2 and v3, not for NFSv4.
3. See which versions are running: cat /proc/fs/nfsd/versions

4. (Recommended) Enable only v4:

   1. In /etc/default/nfs-common, set:

      NEED_STATD="no"
      NEED_IDMAPD="yes"
      

   2. In /etc/default/nfs-kernel-server, set:

      RPCNFSDOPTS="-N 2 -N 3"
      RPCMOUNTDOPTS="--manage-gids -N 2 -N 3"
      

   3. Mask "rpcbind":

      systemctl mask rpcbind.service
      systemctl mask rpcbind.socket
      

Usage

1. Setup a new directory contain all exports in:
   1. Create the container: mkdir /export
   2. Create the export mount dirs within the container.
   3. Mount the exports in the container using bind mounts.
      • Example fstab entry using ZFS: /mnt/zfspool /srv/nfs4/music none bind,defaults,nofail,x-systemd.requires=zfs-mount.service 0 0
   4. Remember to set appropriate permissions.
2. Add filesystems to export in /etc/exports.
   1. (Optional) For NFSv4, the container directory can be set as the root export by specifying option fsid=root.
   2. For a list of options, see exports(5).
3. Update the NFS table: exportfs -ra
   • Or, restart the service: systemctl restart nfs-server
4. (Optional) Show exports: exportfs -v
5. (Optional) Update the firewall:
   • NFSv4 uses only TCP port 2049.

Client

Setup

1. Install: apt install nfs-common

Usage

1. Create a dir to mount the export to.
2. (Optional) Try to mount it: mount -t nfs4 <server-hostname>:<export> <mountpoint>
   • Note that for NFSv4 with a root export, the export path is relative to the root export.
3. (Optional) Make it permanent by adding it to fstab.

ntopng

Setup

1. Install ntopng.
2. Make sure service ntopng is enabled and running.
3. Fix log dir owner: chown nobody:nogroup /var/log/ntopng
4. Configure:
   1. Open /etc/ntopng.conf.
   2. Add -W=<new_port> to enable HTTPS.
   3. (Optional) Set -w=0 to disable HTTP.
5. Restart it (takes a while).

ntpd

Setup

1. Disable systemd-timesyncd NTP client by disabling and stopping systemd-timesyncd.
2. Install ntp.
3. In /etc/ntp.conf, replace existing servers/pools with ntp.justervesenet.no with the iburst option.
4. Test with ntpq -pn (it may take a minute to synchronize).

Postfix

Satellite system

Notes

• When using an SMTP relay, the original IP address will likely be found in the mail headers.
• Make sure DNS is configured correctly (SPF, DKIM, DMARC).

Setup

1. Install: postfix libsasl2-modules mailutils
   • If asked, choose to configure Postfix as a satellite system.
2. Set the FQDN:
   1. Update it in /etc/postfix/main.cf.
   2. Link mailname to hostname (must be FQDN): ln -sf /etc/hostname /etc/mailname
3. Update the root alias in /etc/aliases and run newaliases.
4. Update the main.cf config (example not provided here).
   1. Only listen to localhost: Set “inet_interfaces = loopback-only”
   2. Disable relaying: Set “mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128”
   3. Anonymize banner: “smtpd_banner = $myhostname ESMTP”
5. Relay guides:
   1. Mailgun:
      1. How To Start Sending Email (Mailgun)
      2. How to Set Up a Mail Relay with Postfix and Mailgun on Ubuntu 16.04 (DigitalOcean)
   2. SendGrid:
      1. Postfix (SendGrid)
      2. Use API-key with permission to send mail only.
      3. The API-key username is apikey.
6. Setup address rewrite rules:
   • For fixing the To and From fields, which is typically from root to root.
   • Add the rewrite config (see example below).
   • Reference the config using smtp_header_checks in the main config.
   • Test: postmap -fq "From: root@<FQDN>" regexp:smtp_header_checks
7. Setup relay credentials (SASL):
   1. Credentials file: /etc/postfix/sasl_passwd
   2. Add your credentials using format: [relay_domain]:port user@domain:password
   3. Run: postmap sasl_passwd
   4. Fix permissions: chmod 600 sasl_passwd*
8. Restart postfix.
9. Try sending an email: echo "Test from $(hostname) at time $(date)." | mail -s "Test" root

Examples

# File: smtp_header_checks

/^From:\s*.*\S+@node\.example\.bet.*.*$/ REPLACE From: "Node" <node@example.net>
/^To:\s*.*\S+@node\.example\.net.*$/ REPLACE To: "Someone" <someone@example.net>

Usage

• Send a test mail: echo "Test from $HOSTNAME at time $(date)." | mail -s "Test" root
• Test the config: postconf > /dev/null
• Print the config: postconf -n
• If mails are stuck in the mail queue (mailq) because of previous errors, run postqueue -f to flush them.

Pterodactyl

General

• The panel must be able to communicate with all daemons and all vice versa. The user must be able to communicate with both the panel and daemons.
• Both the panel and daemons need valid TLS certificates.

Panel

Setup

1. Follow the official guide.

Daemon

1. Follow the official guide.
2. Install unzip.
3. Setup a valid TLS certificate.

Game Servers

General

• You can typically watch the installation progress by watching the docker logs.

CSGO

• Use source ID 740 in Pterodactyl (the default) and app ID 730 in Steam Game Server Account Manager, regardless of which app ID the Pterodactyl uses.
• It uses a ton of storage, between 20 and 30 GB last I checked. If you run out of space, the installer will fail with some useless error message.

Router Advertisement Daemon (radvd)

Setup

1. Install and enable radvd.
2. Setup config file: /etc/radvd.conf

Samba

Server

Setup

1. Install: apt install samba

Usage

• Making changes:
  • Change the configuration file: /etc/samba/smb.conf
  • Test the configuration: testparm -t
  • Restart the service: systemctl restart smbd
• Manage access to a share:
  • Add a Linux group for the share, like "smb-media", to restrict user access.
  • Fix permissions for only that group on the system.
  • Configure the share to only allow that group.
  • Add Linux users to the group.
• Manage users:
  • Samba users are somewhat using Linux users but with a different password.
  • To separate pure Samba users from real users, you can add a "smb-" prefix to its username and make it a system user.
  • Create a new Linux (system) user without shell login: useradd -r <name>
    • Or: useradd
  • Add a user and set its password: smbpasswd -a <user>
  • Show users: sudo pdbedit -L -v

Client

Setup

1. Install: apt install cifs-utils

Usage

• Add permanent share:

  1. Create the mountpoint.

  2. Create a credentials file (/root/.credentials/smb/<whatever>):

     user=<user>
     password=<password>
     

  3. In /etc/fstab, add: //<share> <mountpoint> cifs vers=3.1.1,credentials=<file>,iocharset=utf8 0 0

  4. Test it: mount -a

TFTP-HPA

Setup

1. Install tftpd-hpa.
2. Update /etc/default/tftpd-hpa based on the config below.
3. Create the folder /var/tftp with permissions 777 and user-group pair tftp:tftp.
4. Restart it.
5. If it shouldn't automatically start, disble it.

Files

# File: /etc/default/tftpd-hpa

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/var/tftp"
TFTP_ADDRESS=":69"
TFTP_OPTIONS="--create --secure"

Unbound

Setup

1. Install: unbound dns-root-data
2. Setup the config: /etc/unbound/unbound.conf
3. Add hostname variants to /etc/hosts.
4. Configure it in /etc/resolv.conf:
   1. nameserver 127.0.0.1
   2. search <domain>
   3. domain <domain>
5. Configure it in /etc/systemd/resolved.conf:
   1. DNSStubListener=no
   2. DNS=127.0.0.1
   3. Restart systemd-resolved.
6. Test DNSSEC:
   1. drill sigfail.verteiltesysteme.net should give an rcode of SERVFAIL.
   2. drill sigok.verteiltesysteme.net should give an rcode of NOERROR.
7. Make sure dns-root-data is updating root hints in file /usr/share/dns/root.hints.

Troubleshooting

• It sometimes stops resolving names and responds with "servfail".
  • I don't know why. Restarting it works.

Notes

• Use DNS over HTTPS/TLS.
• Setup private addresses for DNS rebinding prevention.

UniFi

Setup

TODO This is just horrible, just use some unofficial Docker image instead.

1. Install MongoDB:
   • See: MongoDB: Install MongoDB Community Edition on Debian or (MongoDB: Install MongoDB on Debian (v3.0))[https://docs.mongodb.com/v3.0/tutorial/install-mongodb-on-debian/]
   • Download and install libssl1.0.0(Debian Jessie).
   • Install for Debian Jessie and MongoDB version 3.4.
   • Enable and start mongod.
2. Install OpenJDK 8.
   • Somehow ...
3. Install UniFi:
   • See: UniFi: How to Install and Update via APT on Debian or Ubuntu
4. Watch logs:
   • UniFi: /usr/lib/unifi/logs/server.log
   • MongoDB: /usr/lib/unifi/logs/mongod.log
5. Allow the following incoming ports (see UniFi - Ports Used):
   • UDP 3478: STUN
   • TCP 8080: Device-controller communication (for devices)
   • TCP 8443: GUI/API (for admins)
   • TCP 8880: HTTP portal (for guests)
   • TCP 8843: HTTPS portal (for guests)
   • TCP 6789: Mobile speedtest (for admins)
   • UDP 10001: Device discovery (for devices)
   • UDP 1900: L2 adoption (optional, for devices)

Using jacobalberty's Unofficial Docker Image

1. Add a system user named "unifi": useradd -r unifi
2. Allow the ports through the firewall (see above).
3. Add a Docker Compose file. See docker-compose.yml.
   • Use host networking mode for L2 adoption to work (if you're not using L3 or SSH adoption).
4. Start the container, open the webpage and follow the wizard.

ZFS

See Storage: ZFS.

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