pcap-config: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/pcap-config - from package: libpcap-devel

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/pcap-config - from package: libpcap0.8-dev

You may install the required package with command apt-get install {package}

Error in other languages:
pcap-config: bevel nie gevind nie
pcap-config: comandă negăsită
pcap-config: comando não encontrado
pcap-config: commande introuvable
pcap-config: command not found
pcap-config: käsku ei ole
pcap-config: không tìm thấy lệnh
pcap-config: komanda nerasta
pcap-config: Kommando nicht gefunden.
pcap-config: kommandot finns inte
pcap-config: komut yok
pcap-config: nie znaleziono polecenia
pcap-config: níor aimsíodh an t-ordú
pcap-config: no se encontró la orden
pcap-config: no s'ha trobat l'ordre
pcap-config: opdracht niet gevonden
pcap-config: parancs nem található
pcap-config: perintah tidak ditemukan
pcap-config: príkaz nenájdený
pcap-config: příkaz nenalezen
pcap-config: команда не найдена
pcap-config: командата не е открита
pcap-config: 命令找不到
pcap-config: コマンドが見つかりません