Permission problem writing to /proc/sys/net/ipv4/conf/ethXX/proxy_arp

commers · 08-28-2010, 04:45 PM

I am trying to enable proxy ARP on Ethernet devices on the fly from user mode scripts, e.g. echo 1 > /proc/sys/net/ipv4/conf/eth0.2/proxy_arp. It has to be dynamic ( I am making VLAN subinterfaces on the fly) and it has to run from user shell, even if I have to use sudo. The problem is if I try sudo echo 1 > ..... or even sudo -s echo > 1 it denies permission. The only way I can make it work is sudo -s<CR>, followed by echo >1...., then exit the root shell. Is there an easier way?

rayfordj · 08-28-2010, 04:54 PM

try this:

Code:

sudo -s 'echo 1 > /proc/sys/net/ipv4/conf/eth0.2/proxy_arp'

The problem stems from the user losing sudo once the command has executed (echo) and then that user that ran sudo does not have permission to write to the file (proxy_arp). When you run the entire command in quote as exampled above the permissions are still escalated when the write to the file (proxy_arp) is attempted so it should succeed.

commers · 08-28-2010, 07:06 PM

That was it...thanks a lot.

corp769 · 08-28-2010, 07:08 PM

Good to know, thanks!