linux/unix system administration

* security: openvpn, ssh plumbing, wireless
* lowlevel network: bind, dhcp, bootp, routing, tunneling, vpn, firewall
* highlevel network: nfs, samba, exim, mailman, spamassasin, pop&imap, apache+cgi
* source package & linux kernel compilation
* debian system administration

programming languages

* C, C++, forth, assembler
* perl, bash+sed+awk
* python
* clisp, scheme

embedded systems

* typical 8bit bare microcontroller work: assembler & forth
* typical 32bit unix/linux embedded work: C

math skills

* basic university level math
* abstract algebra (groups, rings, fields, vector spaces and linear transforms)
* real and complex analysis
* basic numerical methods (solving and optimization)
* applied linear algebra, basics and subspace methods
* discrete signal processing, linear/nonlinear difference equations
* basic nonlinear methods (neural nets and support vector machines)