如何利用正则表达式扫描提取IP并生成指定格式的路由信息输出？

Great question! Instead of just extracting IP addresses in isolation, we can create a targeted regex pattern that captures all the required fields from each routing table line, then map those fields into a dictionary for easy use in your program. Here's how to do it step by step:

Step 1: Define a Regex Pattern to Capture All Fields #

We need a regex that matches the structure of your routing table lines and extracts each component (protocol code, prefix, AD/metric, next-hop, update time, interface). The pattern below handles both single-code protocols (like D for EIGRP) and multi-part codes (like O E2 for OSPF External Type 2):

import re

# Regex pattern to capture all required fields
route_pattern = r'^(\w+)(?:\s+(\w+))?\s+([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)\s+\[([0-9]+/[0-9]+)\]\s+via\s+([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+),\s+([0-9]+:[0-9]+:[0-9]+),\s+(\w+\d+)$'

Let's break down the pattern:

• ^(\w+)(?:\s+(\w+))?: Captures the protocol code (e.g., D or O E2)
• ([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+): Captures the network prefix IP
• \[([0-9]+/[0-9]+)\]: Captures the AD/Metric value inside brackets
• via\s+([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+): Captures the next-hop IP
• ,\s+([0-9]+:[0-9]+:[0-9]+): Captures the last update time
• ,\s+(\w+\d+)$: Captures the outbound interface

Step 2: Map Protocol Codes to Full Names #

Create a dictionary to translate shorthand protocol codes to their full names (adjust this to include all protocols you need to handle):

protocol_mapping = {
    'D': 'EIGRP',
    'O': 'OSPF',
    'O E2': 'OSPF External Type 2',
    # Add other protocol codes here as needed
}

Step 3: Parse the Line and Build the Dictionary #

Use the regex to match your target line, extract the captured groups, and populate your result dictionary:

# Example target line (the highlighted entry from your input)
target_line = "D 10.67.10.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2"

# Match the pattern against the line
match = re.match(route_pattern, target_line)

if match:
    # Extract captured groups
    proto_part1 = match.group(1)
    proto_part2 = match.group(2)
    prefix = match.group(3)
    ad_metric = match.group(4)
    next_hop = match.group(5)
    last_update = match.group(6)
    outbound_int = match.group(7)
    
    # Build the full protocol name
    proto_key = f"{proto_part1} {proto_part2}" if proto_part2 else proto_part1
    protocol = protocol_mapping.get(proto_key, proto_key)  # Fallback to code if no mapping exists
    
    # Create the final dictionary
    route_dict = {
        'Protocol': protocol,
        'Prefix': prefix,
        'AD/Metric': ad_metric,
        'Next-Hop': next_hop,
        'Last Update': last_update,
        'Outbound interface': outbound_int
    }
    
    # Print or use the dictionary in your program
    for key, value in route_dict.items():
        print(f"{key}: {value}")
else:
    print("No match found for the routing table line.")

Output #

Running this code will produce exactly the format you need:

Protocol: EIGRP
Prefix: 10.67.10.0
AD/Metric:200/128
Next-Hop:10.119.254.244
Last Update:0:02:22
Outbound interface: Ethernet2

Processing Multiple Lines #

If you need to process all lines in your routing table, simply loop through each line and apply the same matching logic. This will build a list of route dictionaries that you can pass to other modules in your program.

内容的提问来源于stack exchange，提问作者Calvin Rider