No persistent /dev/net/tun in xen Linux domU… Hacky workaround is adding
mkdir /dev/net && mknod /dev/net/tun c 10 200
while booting (for example in rc.local or in your init.d script which need it).
For example tun device is useful for SSH VPN. Without it, you will have errors like:
channel 0: open failed: administratively prohibited: open failed
I use Nokia E65 phone and SFR (french mobile phone provider). Note there is at least two possibilities for access: wapsfr (for WAP browsing and AFAIK illimited) and websfr (less restricted but with high-cost level). I will only speak about wapsfr here. For connecting, it’s the same method like Orange SFR with Debian excepted you set wapfr instead of orange.fr in /etc/ppp/peers/gprs-wvdial.conf file. Then you are now connected but access seems restricted to 80 and 443 ports via proxy (NetApp/6.0.7 NetCache appliance announced by HTTP headers). For HTTP browsing, you must change your User-Agent to Vodafone/1.0/HTC_Mercury/1.23.163.5/Mozilla/4.0 for HTTP browsing. Of course, no problem for HTTPS browsing. And for SSH (for example SSH tunnel to have a full Internet access), you can use corkscrew and a SSH server reachable on tcp/443 to bypass the proxy. Just “apt-get” it and launch:
ssh -o "ProxyCommand /usr/bin/corkscrew %h %p %h %p" -p 443 login@your_ssh_server