35 lines
647 B
Text
35 lines
647 B
Text
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#!/usr/bin/env sh
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#set -x
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name=$(basename "$0")
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used_tcp_ports=$(sed 1d /proc/net/tcp \
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| awk '($4 == "0A") { print $2 }' \
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| awk -F : '($1 == "00000000" || $1 == "0100007F") { print $2 }' \
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| perl -e 'foreach my $line (<>) { print hex($line) . "\n"; }'
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)
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perror() {
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>&2 printf "%s: %s\n" "$name" "$*"
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}
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port_is_free() {
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for used_port in $used_tcp_ports; do
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[ "$port" = "$used_port" ] && return 1
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done
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:
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}
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port=$1
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if ! { [ "$port" -gt 0 ] && [ "$port" -lt 65536 ]; } 2> /dev/null; then
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perror "you must specify a valid TCP port"
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exit 1
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fi
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while ! port_is_free; do
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port=$((port + 1))
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done
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printf %s\\n "$port"
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