pcap shared libraries: inconsistencies across Linux machines

[Jonathan Gruenhut <jonathan () zetapoint com>]

I am working on 2 Linux machines, compiling the same source code, and linking with -lpcap.  The programs work fine on 
the machines they were compiled on; one uses libpcap.so.0.8.3, and the other uses libpcap.so.0.9.4.

 

The problem is that I would like to run binaries from each one on the other.  I get output such as:

[jonathan@computer83 ~]$ ./program94

./ program94: error while loading shared libraries: libpcap.so.0.9.4: cannot open shared object file: No such file or 
directory

 

(I get the exactly analogous behavior on the other machine, obviously substituting 0.8.3 for 0.9.4.)

 

To be honest, at this point I’m totally mystified.  My (naive) understanding of shared objects in Linux was that as 
long as the major version number was the same, the loader should look up whatever is present on the system.

 

Since I don’t know exactly what information would be most helpful, I’m going to put in one version of everything that 
seems relevant.  This is without loss of generality: the corresponding data from the other way around is exactly what 
one might assume.

 

First, the system:

[jonathan@computer94 ~]$ uname -a

Linux localhost.localdomain 2.6.18-1.2798.fc6 #1 SMP Mon Oct 16 14:54:20 EDT 2006 i686 i686 i386 GNU/Linux

 

ldd output:

[jonathan@computer94 ~]$ ldd program83

        linux-gate.so.1 =>  (0x00422000)

        libnsl.so.1 => /lib/libnsl.so.1 (0x001f6000)

        libpcap.so.0.8.3 => /usr/lib/libpcap.so.0.8.3 (0x00195000)

        libc.so.6 => /lib/libc.so.6 (0x00b47000)

        /lib/ld-linux.so.2 (0x00178000)

 

The so files:

[jonathan@computer94 ~]$ ls -l /usr/lib/*pcap*

lrwxrwxrwx 1 root root     12 Jun 13 20:27 /usr/lib/libpcap.so -> libpcap.so.0

lrwxrwxrwx 1 root root     14 Jun 13 21:22 /usr/lib/libpcap.so.0 -> libpcap.so.0.9

lrwxrwxrwx 1 root root     16 May  3 19:03 /usr/lib/libpcap.so.0.9 -> libpcap.so.0.9.4

-rwxr-xr-x 1 root root 168544 Jul 13  2006 /usr/lib/libpcap.so.0.9.4

 

As it turns out, I’ve gotten it to work by putting libpcap.so.0.8.3 as a symbolic link to libpcap.so.0, but that 
strikes me as a thoroughly displeasing solution esthetically.

 

Thoughts?

 

Many thanks for any help.

Jonathan

 

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