Package: squashfs-tools

"squashfs-tools" package binaries on CentOS:

/sbin/mksquashfs /usr/sbin/unsquashfs

You may install this package on CentOS with yum install squashfs-tools

"squashfs-tools" package binaries on Debian:

/usr/bin/mksquashfs /usr/bin/unsquashfs

You may install this package on Debian with apt-get install squashfs-tools