Linux Administration

Backing up stuff to the cloud is all the rage, and I wanted to give it a try. Since I don’t really want to spend any money on it, I decided to go with the best free provider I could find. I haven’t done too much research, but MEGA’s 50 free GB seems to be the best offer around. They also have a simple CLI tool called megatools (manual). Since I couldn’t find megatools in the official debian repo, I decided to use it from docker. There is no official docker container either, so I just grabbed one at the top (tomzo/megatools-docker). He has added two scripts of his own, which may be helpful if you want to see how megatools work (github), but I feel they are too clunky to use. ...

location ~ ^/(data|html|css|js)/ { try_files $uri $uri/ =404; } location / { try_files $uri $uri/ /index.html; }

Implementation: Login on server as root Install spamassassin through aptitude In /etc/default/spamassassin: Set ENABLED=1 Add/uncomment in /etc/spamassassin/local.cf: rewrite_header Subject *****SPAM***** report_safe 0 In /etc/postfix/master.cf: smtp inet n - - - - smtpd -o content_filter=spamassassin spamassassin unix - n n - - pipe user=debian-spamd argv=/usr/bin/spamc -f -e /usr/sbin/sendmail -oi -f ${sender} ${recipient} Restart services service spamassassin start service postfix reload Verification: Email sent to server with body XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X should have subject rewritten to ****SPAM**** $header

Description: Add greylisting to postfix through postgrey Implementation: Login to server as root Install postgrey through aptitude Append to /etc/postgrey/whitelist-clients: d4.sysinst.ida.liu.se Restart service: service postgrey reload Add to/edit in /etc/postfix/main.cf: smtpd_recipient_restrictions = permit_mynetworks reject_unauth_destination check_policy_service inet:127.0.0.1:10023 Restart service: service postfix reload Verification: Email from any local host should not be greylisted Email from unknown address should be greylisted

Description: Criterias: Accept mail from any SMTP server in the world. Be able to send mail to any SMTP server in the world. Not accept mail for any other destinations than your domain. Meet the requirements of RFC 2821, section 4.5.1 concerning the postmaster address. Should rewrite local usernames to real names through LDAP lookups Forwarded email from satellite systems should have their FQDN rewritten to this server’s Implementation (Main server): Login on server as root: Install postfix through aptitude Select type Internet Site Set System Mail Name to d4.sysinst.ida.liu.se In /etc/postfix/main.cf, add the following lines: mynetworks = 127.0.0.0/8 130.236.179.88/29 [::ffff:127.0.0.0]/104 [::1]/128 masquerade_domains = $mydomain local_header_rewrite_clients = permit_mynetworks sender_canonical_maps = ldap:/etc/postfix/canonical_sender recipient_canonical_maps = ldap:/etc/postfix/canonical_recipent Create /etc/postfix/canonical_sender: search_base = ou=People,dc=d4,dc=sysinst,dc=ida,dc=liu,dc=se server_host = server.d4.sysinst.ida.liu.se bind = no version = 3 domain = d4.sysinst.ida.liu.se query_filter = uid=%u result_attribute = mail Create /etc/postfix/canonical_recipent: search_base = ou=People,dc=d4,dc=sysinst,dc=ida,dc=liu,dc=se server_host = server.d4.sysinst.ida.liu.se bind = no version = 3 domain = d4.sysinst.ida.liu.se query_filter = mail=%s result_attribute = uid Set MX record. Add line to /etc/bind/db.d4.sysinst.ida.liu.se: @ IN MX 10 server.d4.sysinst.ida.liu.se. Restart the services: service postfix restart service bind9 restart Implementation (Satellite Systems/Clients): Install postfix through aptitude Select type Satellite System Set System Mail Name to d4.sysinst.ida.liu.se Set SMTP Relay Host to server.d4.sysinst.ida.liu.se Verification: Test that the server can receive email from generic server outside of LAN Test that the server can send email to generic server outside of LAN Test that the server does not accept email for other domains than d4.sysinst.ida.liu.se Test that all clients can send email to *@d4.sysinst.ida.liu.se and they should end up on server Test that all clients do not have smtp open to LAN/WAN

Description: Install the NFS Kernel Server and allow mappings from the subnet 130.236.179.88/29 Implementation (Server-side): Login as root Install package nfs-kernel-server Add the following line to /etc/hosts.allow: portmap: 130.236.179.88/255.255.255.248 Add the following line to /etc/exports: /usr/local 130.236.179.88/29(ro,root_squash,subtree_check) Restart the services service portmap restart service nfs-kernel-server restart Implementation (Client-side): Login as root Install package nfs-common Attempt a mount: mount -o ro,vers=3 -t nfs server.d4.sysinst.ida.liu.se:/usr/local /usr/local If it works, add the following line to /etc/fstab: server.d4.sysinst.ida.liu.se:/usr/local /usr/local nfs ro,vers=3 0 0 Verification: Create file /usr/local/bin/hello which echoes hello. Run hello on client, should echo hello. Make sure it’s not possible to mount from other host