fixsrcip 0.1 review
Downloadfixsrcip is a tool for binding outgoing TCP and UDP client sockets (IPv4) to specific source IP addresses on multi-homed hosts
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fixsrcip is a tool for binding outgoing TCP and UDP client sockets (IPv4) to specific source IP addresses on multi-homed hosts. It requires a current Linux system. fixsrcip tool uses LD_PRELOAD for preloading a small shared object to executables. The shared object overwrites the connnect() (for TCP) and sendto()/sendmsg() (for UDP) functions.
If you don't understand the short description above, fixsrcip is probably not what you're looking for.
For compiling and installing just run "make" and copy the newly created shared object "fixsrcip.so" and the shell script "fixsrcip" to some suitable places. (i.e. /usr/local/lib resp. /usr/local/bin) Edit fixsrcip and adjust the path to the shared object in the variable FIXSRCIP. (For building fixsrcip you have to install gcc, make and the glibc header files.)
After that you may use fixsrcip like this:
fixsrcip 47.11.8.15 telnet heise.de 80
(This will start telnet for a connction to heise.de on port 80 using the source address 47.11.8.15.)
You may use fixsrcp.so without using the supplied shell script. The shared object relies on $LD_PRELOAD set to the path of the shared object and $FIXSRCIP set to the source IP address to use. This is especially useful for assigning different IP adresses for different users: just put
export LD_PRELOAD=/path/to/fixsrcip.so FIXSRCIP=47.11.8.15
into the respective ~/.bashrc file. Whenever the user logs in he'll make his connections from 47.11.8.15.
No, there's no protection that the user disables fixsrcip at his own will.
No, fixsrcip doesn't work on SETUID programs. This is a limitation of LD_PRELOAD.
No, fixsrcip doesn't work for ICMP. This is a limitation of BSD sockets. Yes, that means that ping doesn't care about $FIXSRCIP.
fixsrcip 0.1 keywords