TCP/IP协议ip头解析

#!/bin/bash
#输入16进制ip头，解析ip头各字段

function bin_padd()
{
	HEX_STR=$1
	for((i=0;i<${#HEX_STR};i++))
	do
      BIN_STR_TMP=`echo "obase=2;ibase=16;${HEX_STR:${i}:1}" | bc`
      BIN_STR_TMP=`printf "%04s" ${BIN_STR_TMP} | sed "s/ /0/g"`
      BIN_STR=`printf "%s%s" ${BIN_STR} ${BIN_STR_TMP}`
	done
	
	echo ${BIN_STR}
}
IPHEAD_HEXSTR=`echo "$1" | tr "a-z" "A-Z"`
if [ $# -eq 0 ];then
    echo -e "Usage:$0 hexstr"
    exit
fi

if [ $((${#IPHEAD_HEXSTR}%2)) -ne 0 ];then
    echo -e "${IPHEAD_HEXSTR} error"  
    exit
fi

#4位版本号
HEX_VERSION_NO=${IPHEAD_HEXSTR:0:1}
DEC_VERSION_NO=`echo "obase=10;ibase=16;${HEX_VERSION_NO}" | bc`

#4位首部长度
HEX_HEAD_LEN=${IPHEAD_HEXSTR:1:1}
DEC_HEAD_LEN=`echo "obase=10;ibase=16;${HEX_HEAD_LEN}" | bc`

#8位服务类型TOS
HEX_SERVICE_TYPE=${IPHEAD_HEXSTR:2:2}
BIN_SERVICE_TYPE=`bin_padd ${HEX_SERVICE_TYPE}`

#16位总长度
HEX_DATA_LEN=${IPHEAD_HEXSTR:4:4}
DEC_DATA_LEN=`echo "obase=10;ibase=16;${HEX_DATA_LEN}" | bc`

#16为标识
HEX_SEQ_NO=${IPHEAD_HEXSTR:8:4}
DEC_SEQ_NO=`echo "obase=10;ibase=16;${HEX_SEQ_NO}" | bc`

#3位标志+13位偏移
HEX_FLG_OFFSET=${IPHEAD_HEXSTR:12:4}
BIN_FLG_OFFSET=`bin_padd ${HEX_FLG_OFFSET}`
BIN_FLG=${BIN_FLG_OFFSET:0:3}
BIN_OFFSET=${BIN_FLG_OFFSET:3:16}
DEC_OFFSET=`echo "obase=10;ibase=2;${BIN_OFFSET}" | bc`

#8位生存时间TTL
HEX_TTL=${IPHEAD_HEXSTR:16:2}
DEC_TTL=`echo "obase=10;ibase=16;${HEX_TTL}" | bc`

#8位协议
HEX_PRO=${IPHEAD_HEXSTR:18:2}
BIN_PRO=`bin_padd ${HEX_PRO}`


#16位校验和
HEX_CHK_SUM=${IPHEAD_HEXSTR:20:4}

#32位源地址
HEX_SRC_IP=${IPHEAD_HEXSTR:24:8}
DEC_SRC_IP1=`echo "obase=10;ibase=16;${HEX_SRC_IP:0:2}" | bc`
DEC_SRC_IP2=`echo "obase=10;ibase=16;${HEX_SRC_IP:2:2}" | bc`
DEC_SRC_IP3=`echo "obase=10;ibase=16;${HEX_SRC_IP:4:2}" | bc`
DEC_SRC_IP4=`echo "obase=10;ibase=16;${HEX_SRC_IP:6:2}" | bc`

#32位目的地址
HEX_DES_IP=${IPHEAD_HEXSTR:32:8}
DEC_DES_IP1=`echo "obase=10;ibase=16;${HEX_DES_IP:0:2}" | bc`
DEC_DES_IP2=`echo "obase=10;ibase=16;${HEX_DES_IP:2:2}" | bc`
DEC_DES_IP3=`echo "obase=10;ibase=16;${HEX_DES_IP:4:2}" | bc`
DEC_DES_IP4=`echo "obase=10;ibase=16;${HEX_DES_IP:6:2}" | bc`

printf "4位版本号:[%d]|4位首部长度:[%d]|8位服务类型TOS:[%s]|16位总长度:[%d]\n" ${DEC_VERSION_NO} ${DEC_HEAD_LEN} ${BIN_SERVICE_TYPE} ${DEC_DATA_LEN}
printf "16为标识:[%d]|3位标志:[%s]|13位偏移:[%s]\n" ${DEC_SEQ_NO} ${BIN_FLG} ${DEC_OFFSET}
printf "8位生存时间TTL:[%d]|8位协议:[%s]|16位校验和:[%s]\n" ${DEC_TTL} ${BIN_PRO} ${HEX_CHK_SUM}
printf "32位源地址:%d.%d.%d.%d\n" ${DEC_SRC_IP1} ${DEC_SRC_IP2} ${DEC_SRC_IP3} ${DEC_SRC_IP4}
printf "32位目的地址:%d.%d.%d.%d\n" ${DEC_DES_IP1} ${DEC_DES_IP2} ${DEC_DES_IP3} ${DEC_DES_IP4}

运行：./iphead 4500002ebe5500007a1151acdeb77ee3c0a81223
4位版本号:[4]|4位首部长度:[5]|8位服务类型TOS:[00000000]|16位总长度:[46]
16为标识:[48725]|3位标志:[000]|13位偏移:[0]
8位生存时间TTL:[122]|8位协议:[00010001]|16位校验和:[51AC]
32位源地址:222.183.126.227
32位目的地址:192.168.18.35

本文地址：https://blog.csdn.net/CodeHouse/article/details/112792870